By the definition of a DVD (yes, just like the various "color" Book standards that defined CDs, there are standards that define DVDs), this new technology will not result in a standard DVD by any means.
More proper terminology might be "in a standard form factor 12cm optical disc".
"Doesn't the carrier freq needs to be > 2 times the data per Shannon?" No, that's Nyquist sampling. To sample an analog signal without aliasing, the sampling rate needs to be 2x the bandwidth of the input signal. Doesn't directly apply here, although it does govern how fast a receiver ADC must be for a software defined radio. NOTE: Carrier frequency does not impose any requirements on the ADC, only channel bandwidth. i.e. an ATSC digital television signal needs at least a 12 MHz sampling rate to be properly sampled, as it is approximately 6 MHz wide regardless of channel carrier frequency.
Shannon's Law states: C = W log (1 + SNR)
C = channel capacity W = channel bandwidth SNR = signal to noise ratio of the channel
Thus, achieving 2.4 bits/sec/Hz is easy - just increase your transmit power or your channel gain to increase SNR. This is why cable modems easily achieve 6 bits/sec/Hz (DOCSIS upper limit is 36 Mbits/sec over a 6 MHz channel, any lower speed is an artificial cap from your provider) - when you are transmitting over a cable instead of free space, losses are (comparatively) low and hence high SNRs are not difficult to achieve.
In this case, it appears the CSIRO guys just threw a lot of bandwidth at the problem (large W).
Easier said than done in the real world. Fixed point-to-point links are easy (directional antennas reduce multipath significantly, what multipath does remain does not change rapidly so requires little receiver processing power to estimate and compensate for.) Mobile environments with rapidly changing high amounts of multipath are where the real challenges are, and thanks to Moore's Law, technology is growing by leaps and bounds in this regard. Error correction techniques known since the 1960s but not implementable until recently (such as LDPC) are now in regular use thanks to increased computing power.
God, I wish there were a -5 "Totally Wrong" moderation.
Carrier frequency has nothing to do with how much information a channel can carry. Channel bandwidth (spectrum used on each side of the carrier frequency) is what matters.
For example, a 6 MHz channel at 450 MHz and one at around 800 MHz have the exact same channel capacity (assuming that the SNR at the receiver is the same on each channel.)
To be specific, the formula for maximum channel capacity of a communications channel is given by Shannon's Law: C = W log (1 + Eb/No), where Eb/No is the signal to noise ratio of the channel and W is the channel bandwidth.
Maximum C for a given SNR and W (or minimum SNR for a given C and W) is not achievable in practice, but recent advances in error control coding techniques such as LDPC and turbo codes have allowed people to get to within just 1 dB of the minimum SNR for a few years. (And yes, this technology is in cell phones. If I recall correctly, turbo codes are used on some cell phone downlinks when transmitting image data that is not latency-sensitive. Unfortunately both turbo codes and LDPC both introduce pretty high latency to a communications system.
2.4 bits/sec/Hz is nothing new. As others have pointed out, plenty of other systems have been doing this for quite some time. Cable modems - I believe the DOCSIS maximum limit is 36 Mbits/sec over a 6 MHz channel. 6 bits/sec/Hz - the nice thing about cable distribution is that the inverse square law goes bye bye and high SNRs are easily achievable. ATSC digital television - 8VSB provides 19.2 mbits/sec over a 6 MHz channel. Just over 3 bits/sec/Hz over relatively long free-space distances, although transmitter power is measured in kilowatts.
There isn't really enough information to figure out exactly what they did, but it looks like the CSIRO people just threw a massive amount of channel bandwidth at the problem. 2.4 bits/sec/Hz means their SNR was not that high.
BTW, yes, it IS true that at higher carrier frequencies, there is more free spectrum available to use wider channels, but there is no direct link between carrier frequency and channel capacity as you claim.
Not if they use expensive materials and/or a manufacturing process that does not scale up very well.
For example, you can try as hard as you want to mass produce something made from titanium, but even if you solve the problems related to actually working with titanium, you still haven't (and won't) solve the problem that titanium itself is expensive.
Same goes for many of these high efficiency solar cells - Many of them use exotic and rare materials. It would be much bigger news if someone figured out how to make a 5% efficiency solar cell that only cost 5% more than the cost of equivalent non-solar-cell roofing material. The world has plenty of unused surface area - watts per square meter is nearly meaningless for most applications, dollars per watt is the big issue.
And one of the key fundamental differences between a/b/g and n is the use of multiple antennas multipath effects to increase data rate by creating multiple independent data channels.
Copper is fundamentally single-path unless you use multple copper connections, but at that point channel bonding is a hell of a lot easier than MIMO.:)
Ugh, that's the most horrible "let's throw some random terms into my post and make myself look smart" post I've seen in a while.
Skin depth has ABSOLUTELY NOTHING to do with this. Skin depth determines how far an RF signal will penetrate into a conductive or semi-conductive material (usually metal, often used to discuss RF penetration into water). Skin depth is a function of wavelength - The shorter the wavelength, the shallower the skin depth. Remember, this is a term of RF penetration *into a conductive or semi-conductive material* and is usually measured in fractions of a millimeter for most metals. It can be a matter of meters for water though, which is why submarines usually are contacted via VLF or ELF (very low frequency/extremely low frequency) - skin depth of VLF/ELF into water is pretty large due to the long wavelength. Still, in general, as far as Wi-Fi goes, skin depth is irrelevant and meaningless.
Freespace RF propagation follows the inverse square law, just like any other electromagnetic radiation.
That said, indoor wireless is typically NOT free space. The nature of indoor wireless means that a signal can take multiple paths between transmitter and receiver. Unfortunately, these paths can sometimes result in the signals at the receiver interfering destructively with each other, causing a significant reduction in signal strength. The best example you might be familiar with is FM radio - have you ever been sitting at an intersection in your car and the reception of the station you were listening to completely dropped out, only to come back to full strength when you moved your car a few feet? That's classic multipath fading.
One solution to multipath is to use two or more antennas to provide what is called diversity. Usually, if one antenna is in a "dead spot", an antenna a half wavelength or so away (or closer but with a different polarization) won't be. This is why almost all normal 802.11a/b/g routers have dual antennas and most PC cards and built-in WLAN cards have dual antennas. The card (usually) selects the one antenna that gives the best reception and uses it. (This is called selection combining. There are other diversity techniques that are better than selection combining but a bit more complex.) Some newer cards may use other diversity reception methods to improve 802.11a/b/g performance.
Now, 802.11n takes diversity to whole new levels. It uses what is commonly called "multiple input multiple output" or MIMO. Fundamentally, MIMO takes multipath and turns it from a disadvantage to an advantage by transmitting different data on each path. Thus, a MIMO system can achieve higher data rates by effectively using multipath to create multiple independent channels.
I have a paper saved somewhere that describes how MIMO works in detail, but the basics are that if you form a matrix with the complex path gains (i.e. both amplitude and phase) between individual transmit and receive antennas (e.g. t1, t2, t3, r1, r2, r3 for a 3x3 MIMO system) of the form [[gT1R1 gT1R2 gT1R3] [gT2R1 gT2R2 gT2R3] [gT3R1 gT3R2 gT3R3]]
(BTW, Malda, LaTeX or MathML please? Octave/Matlab format isn't quite the hottest for representing a matrix in human readable form...)
you can perform operations (I believe a singular value decomposition but my memory could be wrong and it may be another decomposition) on that matrix to form two transformation matrices and a diagonal matrix. The diagonal matrix contains the path gains of three independent pseudochannels (which I believe are either the square root of the matrix eigenvalues, the eigenvalues themselves, or the square of their eigenvalues), and the transformation matrices can be used to take transmissions intended for the three pseudochannels and convert them to actual transmissions/reception on each antenna.
I'm sorry I did such a crap job explaining this, I really need to find that paper as it does a much better job.:)
Beware! Many companies have begun calling anything
Turns out my post was a case of PEBCAK - I set the keyword for media-video/nvidia-drivers to ~x86, not x11-drivers/nvidia-drivers (the NV drivers were moved out of media-video and I didn't realize)
Fan speeds usually have speed steps and not a continuous range. Usually it's "off, slow, or fast". Thus I'm sure he'd know if his fan speeds were changing.
It's a known fact that NVClock no longer supports "legacy" overclocking interfaces (i.e. directly twiddling the card rather than going through CoolBits) very well, and as a result, it's basically impossible to change clock speeds of 6000 and 7000 series mobile GPUs, as NVClock doesn't suport 6ks and 7ks very well without using CoolBits, and NVidia's drivers for Linux forcefully disable CoolBits on mobile GPUs at the moment.
In general, NVidia (and for a while NVClock's author) tried to disable overclocking on mobile GPUs (to avoid damage since laptops usually have tighter thermal tolerances than desktops), completely forgetting that mobile users might actually want to UNDERCLOCK their GPUs. On my old laptop, I had to specifically patch NVClock to consider the GeForce 4 Go 440 to be a desktop GPU so I could underclock it. In this case, it wasn't on NVidia's side, it was NVClock!
I heard back in March/April or so that NVidia was planning on enabling CoolBits for mobile GPUs on Linux some time during the 9x.xx series of drivers, which I don't believe are out for Linux yet. (Nope, looks like 87.76 is the latest...)
Yeah, Dell makes pretty complete service manuals (total disassembly, covering CPU replacements and such) available.
I have an E1705 now (I love the new 17" WUXGA screens), but I still use my I8200 quite a bit too. My first E1705 was a dud (as were many of the early Core Duo systems from any manufacturer, and I suspect I had a dud CPU from the symptoms), but the replacement is rock solid and as mentioned, by old I8200 still serves me well too. I do need to order a new fan assembly for it though... The fans are on their way out.:)
This is me you're talking about. I don't need Keyring crashing even more!:)
(Actually, my version is slightly patched by me to fix issues with the Treo's 5-way navpad. The patches haven't been integrated into a release yet, or at least weren't a year or so ago and I haven't seen any updates to Keyring in a while.)
I can attribute every single crash/reset of my phone within the past six months to a year to particular apps on my phone. In this case, it's GNU Keyring. Keyring really likes to crash my phone if I haven't used Keyring in a while. It's Keyring's way of telling me it wants more love.:)
Yeah. Someone (read: the article submitter) clearly fell victim to Sprint's "The clear alternative to cellular" marketing BS.
"The clear alternative to cellular" translates in Sprint's case to "The clear alternative to ourselves" because their system was still cellular (simply digital instead of analog).
Voice, data, whatever - It still fundamentally relies on breaking up a service area into small cells to increase capacity. Heck, municipal multi-accesspoint WiFi networks take the "cellular" approach to whole new levels, given the incredibly small coverage areas of most WiFi access points.
One can always argue the definition of "small" as far as cells go, but it's usually pretty clear when compared to traditional broadcast TV/radio systems or "public service" VHF/UHF systems which have coverage areas of miles even in densely populated areas.
"However, an effective cure would help him a lot, even at this late date. It becomes increasingly hard to control blood sugar levels, and he doesn't notice when levels wander into dangerous levels anymore. While it wouldn't reverse the damage to the kidneys, vision, etc, it would remove a major cause of further damage and life-threatening blood sugar swings. Even a partial reversal would help a lot."
The issue is whether the risks of the treatment outweigh the benefits of partial/complete reversal.
My opinion is that diabetes is controllable enough that there is no aspect of type I diabetes that is "late stage" enough to warrant rushing into human testing with immunosuppressants. Yes, it could turn out that the immunosuppressants are targeted enough to have minimal side effects, but in this case, the risks of rushing to human trials without taking appropriate care are far greater than staying with the current "status quo", which I admit has its problems, but the potential side effects of any immunosuppressant-based therapy warrant extreme caution.
In this particular case, it seems that the drug in question suppresses some immune responses, but provokes others, which is a potential recipe for disaster, as the botched drug trial of a particular drug earlier this year shows. I forget the name (It was covered on Slashdot...), but it was a drug which was designed to alter the immune system's response. It proved perfectly safe in monkeys (closer relatives to humans than mice) but had horrendous immediate side effects in human trials. The Wikipedia article for the particular substance mentioned in the article (see a response to my own post for the link) indicates that this particular substance is currently not allowed for human use due to its toxicity, so in some ways I'm wondering how in hell they got it to human trials for 2007/2008ish given that it already has a proven record of toxicity issues.
Interestingly enough, the drug mentioned is usually used as an immune booster, although its tendency to suppress autoresponsive T-cells is an unusual side effect.
http://en.wikipedia.org/wiki/Freund's_adjuvant - One of the core aspects of this treatment. Note that it appears to be a REALLY nasty drug with a lot of side effects, and is in fact currently forbidden for use in humans. (So I have no clue how they are using it in a human trial...)
"I must be missing something... if the technique was first described and shown in 2001, then reaffirmed in 2003, why haven't they moved forward with trying to treat humans with severe/end-stage diabetes? In fact, they don't even discuss the possibility, which makes me wonder if there is something else in play (bad side effects for example). This sounds like a MAJOR medical breakthrough, and typically breakthroughs like this are pushed into more expanded trials and even human tests faster than the researchers at MGH are moving forward."
There is no such thing as severe/end-stage type I diabetes. Usually by the time you are diagnosed, you are at the "severe/end stage" - Your pancreatic beta cells are gone or nearly so. Insulin can prolong your life for decades, and if your bloodsugars are carefully controlled (via aggressive and careful diet, insulin dosing, and glucose monitoring), you will live just as long a life as a normal person.
If you're talking about severe diabetes complications (Kidney damage, retina damage, etc.)- By the time those present themselves, the cumulative damage of years of abnormal bloodsugars is done and curing the underlying diabetes isn't going to help.
Last but not least, you clearly missed the "In the 2001 and 2003 studies, Faustman and colleagues treated end-stage nonobese diabetic (NOD) mice with Freund's complete adjuvant, a substance that suppresses the activity of the immune cells that destroy islets in type 1 diabetes." line. Immunosuppressants are scary shit, and usually considered an absolute last-resort treatment when the other choice is death. Admittedly, it sounds like this MIGHT be a rather targeted immunosuppressant with fewer side effects than most, but still, it's an immunosuppressant.
I've been a type I diabetic for over a decade and have been looking forward to a cure for years. While this article gave me a lot of hope, the mention of immunosuppressants took a lot of it away. There are already quite a few treatments for Type I diabetes that are proven to work, but generally are only given to those who are already on immunosuppressants for another reason. (For example, pancreas or pancreatic beta cell transplants are only given to patients already receiving another transplant who will be on antirejection drugs and immunosuppressants anyway.)
That said, it sounds like there are fewer side effects than other immunosuppressants, as I have heard that there are plans for human trials starting in 2007 or 2008. Six years from the first results in mice to the first human trials is actually quite quick. There are plenty of examples of cases where botched human trials nearly killed the test cases. (Remember that incident a year or two in London where 6-8 test patients basically swelled up like balloons and found that six months later most of them had trashed immune systems and the beginnings of cancer?) People are REALLY, REALLY careful with human trials.
It sounds like they are conducting one more large-scale study in mice before beginning human trials. They didn't have money for it before, but they received a large amount from one of Lee Iacocca's charities to fund further studies.
Given the involvement of immunosuppressants, I hope they are extra careful with human trials. I can wait another decade if it means I won't be developing cancer or a few years after treatment.
OK, yeah, the P-4 supported rudimentary clock modulation, but clock modulation without a voltage change doesn't benefit you that much.
Pentium M, Core Duo, and mobile C2D (Merom) are not what I was talking about, as laptop hardware has supported power management for a long time. I was referring primarily to desktop CPUs.
"1) run a more efficient O/S or optimize the O/S for lower power" Not "a few lines of code" as the article claims. Plus I believe Windows now supports idle/halt instructions.
"2) run less spyware, background crap, etc. (or optimize the background stuff)" Again, not "a few lines of code"
"3) run a modern, efficient CPU with minimal amount of RAM and low-power disk (select lower-power hardware)" Not "a few lines of code", not even "as much code as you can throw at it". Fundamentally not a software solution.
"4) replace some hard disks with solid-state memory (FLASH)" Again, not a software solution.
"5) replace some (10%?) desktops and laptops with low-power devices (e.g., OLPC but for business)" See 3) and 4)
"6) have a more efficient power supply (e.g., Google's proposal, or DC used in data centers)" 3) 4) and 5)
"7) replace monitors with lower-power LCDs" 3) 4) 5) and 6)
"8) replace screen savers with blank screens and turn off hard disk after N minutes" About the only suggestion you've made so far that can be backported to XP. In fact, XP supports both of these already.
"9) turn computers off when not using them" Can't be fixed in software by Microsoft.
"10) get computers that support suspend/hibernate and use those features (work with your OEM's)" Again, this either cannot be solved in software, or requires more than the "few lines of code" the article claims.
"11) consolidate lots of servers onto fewer, more efficient servers (vmware/xen)" More than a "few lines of code" and most likely also requires hardware changes.
Remember, fundamentally, the original article claims that Microsoft can cause huge power savings with a "few lines of code" improved in Windows XP. My counterclaim is that this is not possible without: a) Improved hardware (Note "ready for Windows Vista" certification. Vista not only means a major software architecture, but potentially requiring hardware to support power management features for "Vista compatible" certification.) Not something MS can backport to XP. b) Fundamental software architecture improvements. Already planned for Vista as far as power management, not easily backportable to XP in all likelihood.
Or, of course, Microsoft could send out an update that breaks all XP machines and forces users to switch to Linux.:)
Number of non-mobile computers out there that support CPU frequency and clock scaling - Very few.
AMD has only had that on the market for desktop CPUs for 3-4 years (or less), and Intel has only had it on the market for 3-4 months (since the Core 2 Duo launch for the desktop). No previous Intel desktop CPU supported any power management of significance.
This is one of those aspects of hardware that can't be changed in software. If the hardware doesn't support it (and for a few more years, most machines won't, people overestimate how often the "average Joe" replaces his hardware, same for corporate users), no software update will do a thing.
If he's talking about suspend and hibernate - That stuff is disabled by default because it rarely ever works properly. Of all the machines I own, only one (My newest machine) can wake up from hibernation with 100% reliability. If Microsoft tried to force hibernation to be enabled on all users, they would have a massive lawsuit on their hands due to all the machines that can't handle it.
With the exception of the Atheros HAL (which, while semi-closed, has a decent number of people outside of Atheros looking at it - Most of the Atheros HAL ports are done by non-Atheros volunteers who have signed NDAs for the source), pretty much all other binary "blobs" only execute on the card itself. Whether the blob has a bug or not, as long as the code interfacing with the card that runs as part of the OS kernel itself is open-source and secure, a firmware blob that runs on the card itself cannot cause a host machine compromise.
Remember here that I am talking about binary firmware "blobs" and not the complete driver solution (which usually involves firmware on the card combined with kernel code in the host OS). As long as the host OS portion is open source and properly written, one should be immune from host machine compromise.
At the same "Fanfest" during which the merger was announced (which I believe is still going on), CCP gave an official subscriber count number - it was something like 146-148k subs.
EVE is small, but as one of the other posters said, it's been constantly growing.
When I first quit EVE in mid-2004 (about a year after release) my opinion was that it was a great concept with crap implementation. After hearing lots of good things about it this past summer (many from Slashdot posters), I decided to come back in July. My opinion is that CCP has matured drastically from the original "college grads with a dream" start, consisting mostly of an inexperienced dev team that apparently were slackers in college. (One of the girls in my first EVE corp was from Iceland and she and the original EVE team had quite a few mutual friends in school.) CCP has learned a lot from their mistakes and the CCP of 2006 is almost unrecognizable compared to the CCP of 2003-2004. That shows in their steadily increasing subscriber counts.
I suspect that those subscriber counts will continue increasing, as one of the current limiting factors to those counts seems to be overcrowding. (The "everyone in one universe" thing is very cool except for that one problem) With their next upgrade (CCP calls them expansions, but expansion in MMOGs usually means "pay us more money to be able to access the cool new stuff"), CCP is adding eight new regions of space, which should help a lot in terms of crowding. Hopefully the hardware they've added/will be adding will also help with some of the other symptoms of overcrowding. (Although no matter what, until they can parallelize calculations on a node between multiple CPUs for that node, they'll continue having problems with major fleet battles causing the node that hosts the solar system they occur in to drop.)
My Philips HN100s (admittedly a rather low-end model) do very little as far as noises from a computer (drive whine, cooling fans, etc.) They're excellent against lower bass frequencies (automotive engine noise, airplane engine noise, lawnmower noise).
Also, wearing circumaural ANC headphones is going to be a lot more annoying than almost-invisible earplugs. The in-ear ANC headsets (like the Philips SHN2500s) are absolutely awful compared to good passive-isolating earphones or good earplugs. In fact, my experience with the SHN2500s was that they added more noise than they removed in most environments.
As far as in-ear passive isolating headphones, I have tried the following: Sony MDR-EXsomethingorother - Silicone rubber earpieces, with rubber hooks that go over your ears. Extremely uncomfortable and not much isolation. $50 JVC HA-FX33 "Marshmallow" headphones - These STILL don't appear on JVC's website anywhere, and I have only seen them at Wal-Mart stores. $20, decent isolation, pretty comfortable, excellent sound. Radio Shack "NR-1" noise isolating earphones - Great isolation and comfort, not very good bass response. I keep them around for extreme environments where isolation is more important than bass response and sound quality. $40
I haven't used any of the more expensive in-ear monitors. Shure E2cs and E3cs are popular, as are Westone UM1s and UM2s. The UM1/UM2 appear to use the exact same "Comply" tips as the Rat Shack units, so should have the same isolation and comfort, but hopefully better bass response and sound quality due to better drivers.
For the most extreme enviroments, such as the cabin of a Saab 340 turboprop aircraft, my personal favorite is a combo the Rat Shack in-ears connected to an audio source (laptop or iPod) with the Philips HN100s placed over them. Neither of them alone is sufficient for the interior cabin of a turboprop aircraft.
Slashdot Mirror
By the definition of a DVD (yes, just like the various "color" Book standards that defined CDs, there are standards that define DVDs), this new technology will not result in a standard DVD by any means.
More proper terminology might be "in a standard form factor 12cm optical disc".
They probably do have such magic powers, bought from the likes of Cummins Power Generation - http://www.cumminspower.com/na/
"Doesn't the carrier freq needs to be > 2 times the data per Shannon?"
No, that's Nyquist sampling. To sample an analog signal without aliasing, the sampling rate needs to be 2x the bandwidth of the input signal. Doesn't directly apply here, although it does govern how fast a receiver ADC must be for a software defined radio. NOTE: Carrier frequency does not impose any requirements on the ADC, only channel bandwidth. i.e. an ATSC digital television signal needs at least a 12 MHz sampling rate to be properly sampled, as it is approximately 6 MHz wide regardless of channel carrier frequency.
Shannon's Law states:
C = W log (1 + SNR)
C = channel capacity
W = channel bandwidth
SNR = signal to noise ratio of the channel
Thus, achieving 2.4 bits/sec/Hz is easy - just increase your transmit power or your channel gain to increase SNR. This is why cable modems easily achieve 6 bits/sec/Hz (DOCSIS upper limit is 36 Mbits/sec over a 6 MHz channel, any lower speed is an artificial cap from your provider) - when you are transmitting over a cable instead of free space, losses are (comparatively) low and hence high SNRs are not difficult to achieve.
In this case, it appears the CSIRO guys just threw a lot of bandwidth at the problem (large W).
Easier said than done in the real world. Fixed point-to-point links are easy (directional antennas reduce multipath significantly, what multipath does remain does not change rapidly so requires little receiver processing power to estimate and compensate for.) Mobile environments with rapidly changing high amounts of multipath are where the real challenges are, and thanks to Moore's Law, technology is growing by leaps and bounds in this regard. Error correction techniques known since the 1960s but not implementable until recently (such as LDPC) are now in regular use thanks to increased computing power.
God, I wish there were a -5 "Totally Wrong" moderation.
Carrier frequency has nothing to do with how much information a channel can carry. Channel bandwidth (spectrum used on each side of the carrier frequency) is what matters.
For example, a 6 MHz channel at 450 MHz and one at around 800 MHz have the exact same channel capacity (assuming that the SNR at the receiver is the same on each channel.)
To be specific, the formula for maximum channel capacity of a communications channel is given by Shannon's Law:
C = W log (1 + Eb/No), where Eb/No is the signal to noise ratio of the channel and W is the channel bandwidth.
Maximum C for a given SNR and W (or minimum SNR for a given C and W) is not achievable in practice, but recent advances in error control coding techniques such as LDPC and turbo codes have allowed people to get to within just 1 dB of the minimum SNR for a few years. (And yes, this technology is in cell phones. If I recall correctly, turbo codes are used on some cell phone downlinks when transmitting image data that is not latency-sensitive. Unfortunately both turbo codes and LDPC both introduce pretty high latency to a communications system.
2.4 bits/sec/Hz is nothing new. As others have pointed out, plenty of other systems have been doing this for quite some time.
Cable modems - I believe the DOCSIS maximum limit is 36 Mbits/sec over a 6 MHz channel. 6 bits/sec/Hz - the nice thing about cable distribution is that the inverse square law goes bye bye and high SNRs are easily achievable.
ATSC digital television - 8VSB provides 19.2 mbits/sec over a 6 MHz channel. Just over 3 bits/sec/Hz over relatively long free-space distances, although transmitter power is measured in kilowatts.
There isn't really enough information to figure out exactly what they did, but it looks like the CSIRO people just threw a massive amount of channel bandwidth at the problem. 2.4 bits/sec/Hz means their SNR was not that high.
BTW, yes, it IS true that at higher carrier frequencies, there is more free spectrum available to use wider channels, but there is no direct link between carrier frequency and channel capacity as you claim.
Not if they use expensive materials and/or a manufacturing process that does not scale up very well.
For example, you can try as hard as you want to mass produce something made from titanium, but even if you solve the problems related to actually working with titanium, you still haven't (and won't) solve the problem that titanium itself is expensive.
Same goes for many of these high efficiency solar cells - Many of them use exotic and rare materials. It would be much bigger news if someone figured out how to make a 5% efficiency solar cell that only cost 5% more than the cost of equivalent non-solar-cell roofing material. The world has plenty of unused surface area - watts per square meter is nearly meaningless for most applications, dollars per watt is the big issue.
That makes the assumption that a high efficiency panel of a given area is the same price.
More likely it is:
1 square meter 10% panel at $50/square meter - $x per watt
0.25 square meter 40% panel at $5000/square meter - $25x per watt
Don't believe me - look at the prices of the high-efficiency cells used for spacecraft. Their price range is in hundreds of dollars per square inch.
And one of the key fundamental differences between a/b/g and n is the use of multiple antennas multipath effects to increase data rate by creating multiple independent data channels.
:)
Copper is fundamentally single-path unless you use multple copper connections, but at that point channel bonding is a hell of a lot easier than MIMO.
Ugh, that's the most horrible "let's throw some random terms into my post and make myself look smart" post I've seen in a while.
:)
Skin depth has ABSOLUTELY NOTHING to do with this. Skin depth determines how far an RF signal will penetrate into a conductive or semi-conductive material (usually metal, often used to discuss RF penetration into water). Skin depth is a function of wavelength - The shorter the wavelength, the shallower the skin depth. Remember, this is a term of RF penetration *into a conductive or semi-conductive material* and is usually measured in fractions of a millimeter for most metals. It can be a matter of meters for water though, which is why submarines usually are contacted via VLF or ELF (very low frequency/extremely low frequency) - skin depth of VLF/ELF into water is pretty large due to the long wavelength. Still, in general, as far as Wi-Fi goes, skin depth is irrelevant and meaningless.
Freespace RF propagation follows the inverse square law, just like any other electromagnetic radiation.
That said, indoor wireless is typically NOT free space. The nature of indoor wireless means that a signal can take multiple paths between transmitter and receiver. Unfortunately, these paths can sometimes result in the signals at the receiver interfering destructively with each other, causing a significant reduction in signal strength. The best example you might be familiar with is FM radio - have you ever been sitting at an intersection in your car and the reception of the station you were listening to completely dropped out, only to come back to full strength when you moved your car a few feet? That's classic multipath fading.
One solution to multipath is to use two or more antennas to provide what is called diversity. Usually, if one antenna is in a "dead spot", an antenna a half wavelength or so away (or closer but with a different polarization) won't be. This is why almost all normal 802.11a/b/g routers have dual antennas and most PC cards and built-in WLAN cards have dual antennas. The card (usually) selects the one antenna that gives the best reception and uses it. (This is called selection combining. There are other diversity techniques that are better than selection combining but a bit more complex.) Some newer cards may use other diversity reception methods to improve 802.11a/b/g performance.
Now, 802.11n takes diversity to whole new levels. It uses what is commonly called "multiple input multiple output" or MIMO. Fundamentally, MIMO takes multipath and turns it from a disadvantage to an advantage by transmitting different data on each path. Thus, a MIMO system can achieve higher data rates by effectively using multipath to create multiple independent channels.
I have a paper saved somewhere that describes how MIMO works in detail, but the basics are that if you form a matrix with the complex path gains (i.e. both amplitude and phase) between individual transmit and receive antennas (e.g. t1, t2, t3, r1, r2, r3 for a 3x3 MIMO system) of the form
[[gT1R1 gT1R2 gT1R3]
[gT2R1 gT2R2 gT2R3]
[gT3R1 gT3R2 gT3R3]]
(BTW, Malda, LaTeX or MathML please? Octave/Matlab format isn't quite the hottest for representing a matrix in human readable form...)
you can perform operations (I believe a singular value decomposition but my memory could be wrong and it may be another decomposition) on that matrix to form two transformation matrices and a diagonal matrix. The diagonal matrix contains the path gains of three independent pseudochannels (which I believe are either the square root of the matrix eigenvalues, the eigenvalues themselves, or the square of their eigenvalues), and the transformation matrices can be used to take transmissions intended for the three pseudochannels and convert them to actual transmissions/reception on each antenna.
I'm sorry I did such a crap job explaining this, I really need to find that paper as it does a much better job.
Beware! Many companies have begun calling anything
Turns out my post was a case of PEBCAK - I set the keyword for media-video/nvidia-drivers to ~x86, not x11-drivers/nvidia-drivers (the NV drivers were moved out of media-video and I didn't realize)
Going to try it on my laptop tonight.
Fan speeds usually have speed steps and not a continuous range. Usually it's "off, slow, or fast". Thus I'm sure he'd know if his fan speeds were changing.
It's a known fact that NVClock no longer supports "legacy" overclocking interfaces (i.e. directly twiddling the card rather than going through CoolBits) very well, and as a result, it's basically impossible to change clock speeds of 6000 and 7000 series mobile GPUs, as NVClock doesn't suport 6ks and 7ks very well without using CoolBits, and NVidia's drivers for Linux forcefully disable CoolBits on mobile GPUs at the moment.
In general, NVidia (and for a while NVClock's author) tried to disable overclocking on mobile GPUs (to avoid damage since laptops usually have tighter thermal tolerances than desktops), completely forgetting that mobile users might actually want to UNDERCLOCK their GPUs. On my old laptop, I had to specifically patch NVClock to consider the GeForce 4 Go 440 to be a desktop GPU so I could underclock it. In this case, it wasn't on NVidia's side, it was NVClock!
I heard back in March/April or so that NVidia was planning on enabling CoolBits for mobile GPUs on Linux some time during the 9x.xx series of drivers, which I don't believe are out for Linux yet. (Nope, looks like 87.76 is the latest...)
Yeah, Dell makes pretty complete service manuals (total disassembly, covering CPU replacements and such) available.
:)
I have an E1705 now (I love the new 17" WUXGA screens), but I still use my I8200 quite a bit too. My first E1705 was a dud (as were many of the early Core Duo systems from any manufacturer, and I suspect I had a dud CPU from the symptoms), but the replacement is rock solid and as mentioned, by old I8200 still serves me well too. I do need to order a new fan assembly for it though... The fans are on their way out.
This is me you're talking about. I don't need Keyring crashing even more! :)
(Actually, my version is slightly patched by me to fix issues with the Treo's 5-way navpad. The patches haven't been integrated into a release yet, or at least weren't a year or so ago and I haven't seen any updates to Keyring in a while.)
I can attribute every single crash/reset of my phone within the past six months to a year to particular apps on my phone. In this case, it's GNU Keyring. Keyring really likes to crash my phone if I haven't used Keyring in a while. It's Keyring's way of telling me it wants more love. :)
Well, in terms of EMI problems from GSM phones, you couldn't have said it better.
In the essay, the EMI problems (normally a bug/annoyance) are used as an indication your phone is doing something it shouldn't.
Yeah. Someone (read: the article submitter) clearly fell victim to Sprint's "The clear alternative to cellular" marketing BS.
"The clear alternative to cellular" translates in Sprint's case to "The clear alternative to ourselves" because their system was still cellular (simply digital instead of analog).
Voice, data, whatever - It still fundamentally relies on breaking up a service area into small cells to increase capacity. Heck, municipal multi-accesspoint WiFi networks take the "cellular" approach to whole new levels, given the incredibly small coverage areas of most WiFi access points.
One can always argue the definition of "small" as far as cells go, but it's usually pretty clear when compared to traditional broadcast TV/radio systems or "public service" VHF/UHF systems which have coverage areas of miles even in densely populated areas.
"However, an effective cure would help him a lot, even at this late date. It becomes increasingly hard to control blood sugar levels, and he doesn't notice when levels wander into dangerous levels anymore. While it wouldn't reverse the damage to the kidneys, vision, etc, it would remove a major cause of further damage and life-threatening blood sugar swings. Even a partial reversal would help a lot."
The issue is whether the risks of the treatment outweigh the benefits of partial/complete reversal.
My opinion is that diabetes is controllable enough that there is no aspect of type I diabetes that is "late stage" enough to warrant rushing into human testing with immunosuppressants. Yes, it could turn out that the immunosuppressants are targeted enough to have minimal side effects, but in this case, the risks of rushing to human trials without taking appropriate care are far greater than staying with the current "status quo", which I admit has its problems, but the potential side effects of any immunosuppressant-based therapy warrant extreme caution.
In this particular case, it seems that the drug in question suppresses some immune responses, but provokes others, which is a potential recipe for disaster, as the botched drug trial of a particular drug earlier this year shows. I forget the name (It was covered on Slashdot...), but it was a drug which was designed to alter the immune system's response. It proved perfectly safe in monkeys (closer relatives to humans than mice) but had horrendous immediate side effects in human trials. The Wikipedia article for the particular substance mentioned in the article (see a response to my own post for the link) indicates that this particular substance is currently not allowed for human use due to its toxicity, so in some ways I'm wondering how in hell they got it to human trials for 2007/2008ish given that it already has a proven record of toxicity issues.
Interestingly enough, the drug mentioned is usually used as an immune booster, although its tendency to suppress autoresponsive T-cells is an unusual side effect.
http://en.wikipedia.org/wiki/Freund's_adjuvant - One of the core aspects of this treatment. Note that it appears to be a REALLY nasty drug with a lot of side effects, and is in fact currently forbidden for use in humans. (So I have no clue how they are using it in a human trial...)
http://en.wikipedia.org/wiki/Denise_Faustman - There's a lot of controversy surrounding this treatment.
Stem cells or no stem cells, cancer is a known side effect of nearly any immunosuppressant, which happens to be a fundamental part of this protocol.
"I must be missing something ... if the technique was first described and shown in 2001, then reaffirmed in 2003, why haven't they moved forward with trying to treat humans with severe/end-stage diabetes? In fact, they don't even discuss the possibility, which makes me wonder if there is something else in play (bad side effects for example). This sounds like a MAJOR medical breakthrough, and typically breakthroughs like this are pushed into more expanded trials and even human tests faster than the researchers at MGH are moving forward."
There is no such thing as severe/end-stage type I diabetes. Usually by the time you are diagnosed, you are at the "severe/end stage" - Your pancreatic beta cells are gone or nearly so. Insulin can prolong your life for decades, and if your bloodsugars are carefully controlled (via aggressive and careful diet, insulin dosing, and glucose monitoring), you will live just as long a life as a normal person.
If you're talking about severe diabetes complications (Kidney damage, retina damage, etc.)- By the time those present themselves, the cumulative damage of years of abnormal bloodsugars is done and curing the underlying diabetes isn't going to help.
Last but not least, you clearly missed the "In the 2001 and 2003 studies, Faustman and colleagues treated end-stage nonobese diabetic (NOD) mice with Freund's complete adjuvant, a substance that suppresses the activity of the immune cells that destroy islets in type 1 diabetes." line. Immunosuppressants are scary shit, and usually considered an absolute last-resort treatment when the other choice is death. Admittedly, it sounds like this MIGHT be a rather targeted immunosuppressant with fewer side effects than most, but still, it's an immunosuppressant.
I've been a type I diabetic for over a decade and have been looking forward to a cure for years. While this article gave me a lot of hope, the mention of immunosuppressants took a lot of it away. There are already quite a few treatments for Type I diabetes that are proven to work, but generally are only given to those who are already on immunosuppressants for another reason. (For example, pancreas or pancreatic beta cell transplants are only given to patients already receiving another transplant who will be on antirejection drugs and immunosuppressants anyway.)
That said, it sounds like there are fewer side effects than other immunosuppressants, as I have heard that there are plans for human trials starting in 2007 or 2008. Six years from the first results in mice to the first human trials is actually quite quick. There are plenty of examples of cases where botched human trials nearly killed the test cases. (Remember that incident a year or two in London where 6-8 test patients basically swelled up like balloons and found that six months later most of them had trashed immune systems and the beginnings of cancer?) People are REALLY, REALLY careful with human trials.
It sounds like they are conducting one more large-scale study in mice before beginning human trials. They didn't have money for it before, but they received a large amount from one of Lee Iacocca's charities to fund further studies.
Given the involvement of immunosuppressants, I hope they are extra careful with human trials. I can wait another decade if it means I won't be developing cancer or a few years after treatment.
OK, yeah, the P-4 supported rudimentary clock modulation, but clock modulation without a voltage change doesn't benefit you that much.
Pentium M, Core Duo, and mobile C2D (Merom) are not what I was talking about, as laptop hardware has supported power management for a long time. I was referring primarily to desktop CPUs.
"1) run a more efficient O/S or optimize the O/S for lower power"
:)
Not "a few lines of code" as the article claims. Plus I believe Windows now supports idle/halt instructions.
"2) run less spyware, background crap, etc. (or optimize the background stuff)"
Again, not "a few lines of code"
"3) run a modern, efficient CPU with minimal amount of RAM and low-power disk (select lower-power hardware)"
Not "a few lines of code", not even "as much code as you can throw at it". Fundamentally not a software solution.
"4) replace some hard disks with solid-state memory (FLASH)"
Again, not a software solution.
"5) replace some (10%?) desktops and laptops with low-power devices (e.g., OLPC but for business)"
See 3) and 4)
"6) have a more efficient power supply (e.g., Google's proposal, or DC used in data centers)"
3) 4) and 5)
"7) replace monitors with lower-power LCDs"
3) 4) 5) and 6)
"8) replace screen savers with blank screens and turn off hard disk after N minutes"
About the only suggestion you've made so far that can be backported to XP. In fact, XP supports both of these already.
"9) turn computers off when not using them"
Can't be fixed in software by Microsoft.
"10) get computers that support suspend/hibernate and use those features (work with your OEM's)"
Again, this either cannot be solved in software, or requires more than the "few lines of code" the article claims.
"11) consolidate lots of servers onto fewer, more efficient servers (vmware/xen)"
More than a "few lines of code" and most likely also requires hardware changes.
Remember, fundamentally, the original article claims that Microsoft can cause huge power savings with a "few lines of code" improved in Windows XP. My counterclaim is that this is not possible without:
a) Improved hardware (Note "ready for Windows Vista" certification. Vista not only means a major software architecture, but potentially requiring hardware to support power management features for "Vista compatible" certification.) Not something MS can backport to XP.
b) Fundamental software architecture improvements. Already planned for Vista as far as power management, not easily backportable to XP in all likelihood.
Or, of course, Microsoft could send out an update that breaks all XP machines and forces users to switch to Linux.
Number of non-mobile computers out there that support CPU frequency and clock scaling - Very few.
AMD has only had that on the market for desktop CPUs for 3-4 years (or less), and Intel has only had it on the market for 3-4 months (since the Core 2 Duo launch for the desktop). No previous Intel desktop CPU supported any power management of significance.
This is one of those aspects of hardware that can't be changed in software. If the hardware doesn't support it (and for a few more years, most machines won't, people overestimate how often the "average Joe" replaces his hardware, same for corporate users), no software update will do a thing.
If he's talking about suspend and hibernate - That stuff is disabled by default because it rarely ever works properly. Of all the machines I own, only one (My newest machine) can wake up from hibernation with 100% reliability. If Microsoft tried to force hibernation to be enabled on all users, they would have a massive lawsuit on their hands due to all the machines that can't handle it.
Where are my mod points when I need them.
With the exception of the Atheros HAL (which, while semi-closed, has a decent number of people outside of Atheros looking at it - Most of the Atheros HAL ports are done by non-Atheros volunteers who have signed NDAs for the source), pretty much all other binary "blobs" only execute on the card itself. Whether the blob has a bug or not, as long as the code interfacing with the card that runs as part of the OS kernel itself is open-source and secure, a firmware blob that runs on the card itself cannot cause a host machine compromise.
Remember here that I am talking about binary firmware "blobs" and not the complete driver solution (which usually involves firmware on the card combined with kernel code in the host OS). As long as the host OS portion is open source and properly written, one should be immune from host machine compromise.
At the same "Fanfest" during which the merger was announced (which I believe is still going on), CCP gave an official subscriber count number - it was something like 146-148k subs.
EVE is small, but as one of the other posters said, it's been constantly growing.
When I first quit EVE in mid-2004 (about a year after release) my opinion was that it was a great concept with crap implementation. After hearing lots of good things about it this past summer (many from Slashdot posters), I decided to come back in July. My opinion is that CCP has matured drastically from the original "college grads with a dream" start, consisting mostly of an inexperienced dev team that apparently were slackers in college. (One of the girls in my first EVE corp was from Iceland and she and the original EVE team had quite a few mutual friends in school.) CCP has learned a lot from their mistakes and the CCP of 2006 is almost unrecognizable compared to the CCP of 2003-2004. That shows in their steadily increasing subscriber counts.
I suspect that those subscriber counts will continue increasing, as one of the current limiting factors to those counts seems to be overcrowding. (The "everyone in one universe" thing is very cool except for that one problem) With their next upgrade (CCP calls them expansions, but expansion in MMOGs usually means "pay us more money to be able to access the cool new stuff"), CCP is adding eight new regions of space, which should help a lot in terms of crowding. Hopefully the hardware they've added/will be adding will also help with some of the other symptoms of overcrowding. (Although no matter what, until they can parallelize calculations on a node between multiple CPUs for that node, they'll continue having problems with major fleet battles causing the node that hosts the solar system they occur in to drop.)
My Philips HN100s (admittedly a rather low-end model) do very little as far as noises from a computer (drive whine, cooling fans, etc.) They're excellent against lower bass frequencies (automotive engine noise, airplane engine noise, lawnmower noise).
Also, wearing circumaural ANC headphones is going to be a lot more annoying than almost-invisible earplugs. The in-ear ANC headsets (like the Philips SHN2500s) are absolutely awful compared to good passive-isolating earphones or good earplugs. In fact, my experience with the SHN2500s was that they added more noise than they removed in most environments.
As far as in-ear passive isolating headphones, I have tried the following:
Sony MDR-EXsomethingorother - Silicone rubber earpieces, with rubber hooks that go over your ears. Extremely uncomfortable and not much isolation. $50
JVC HA-FX33 "Marshmallow" headphones - These STILL don't appear on JVC's website anywhere, and I have only seen them at Wal-Mart stores. $20, decent isolation, pretty comfortable, excellent sound.
Radio Shack "NR-1" noise isolating earphones - Great isolation and comfort, not very good bass response. I keep them around for extreme environments where isolation is more important than bass response and sound quality. $40
I haven't used any of the more expensive in-ear monitors. Shure E2cs and E3cs are popular, as are Westone UM1s and UM2s. The UM1/UM2 appear to use the exact same "Comply" tips as the Rat Shack units, so should have the same isolation and comfort, but hopefully better bass response and sound quality due to better drivers.
For the most extreme enviroments, such as the cabin of a Saab 340 turboprop aircraft, my personal favorite is a combo the Rat Shack in-ears connected to an audio source (laptop or iPod) with the Philips HN100s placed over them. Neither of them alone is sufficient for the interior cabin of a turboprop aircraft.