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Low-Carb Diet Trumps Low-Fat Diet In Major New Study

MattskEE Re:What they don't tell you (388 comments)

Ever since I can remember, we have been bombarded by th e concept that there is a scale of healthy eating, and that elimination of as much fat as possible is desirable, and the ne plus ultra of healthy living is veganism, followed by vegatarianism, then low fat/high carb, then the unwashed masses of high protein, and the soulles spawn of Satan - the Atkinists.

You seem older than I and so our perspectives are a bit different. I started cooking my own food around 10 years ago. I always got the impression that vegan/vegetarian lifestyles *could* be quite healthy, but that this had more to do with the fact that these folks are more likely to put more thought and planning into their diet than the average america, eating more fruit and veg, and not eating as many empty calories in general.

2 hours ago
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Reported iCloud Hack Leaks Hundreds of Private Celebrity Photos

MattskEE Re:Where are these photos? (301 comments)

Once the genie's out of the bottle it's over. Apparently Lawrence's lawyers are threatening to sue or refer for criminal prosecution anyone that shares the photos of her. I very much doubt they'll have a lot of luck though, even if the original source of the leak is found. If anything they're just going to make it worse via Streisand Effect.

Seriously, the Streisand Effect? This is already all over the internet and news, going after those responsible for it won't change that in the slightest.

yesterday
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Scientists Craft Seamless 2D Semiconductor Junctions

MattskEE Re:Two dimensional? (49 comments)

I'm quite sure they're not idiots who really think this is a freakin' 2D plane.

Not to be pedantic, but from the same paper abstract but two sentences ahead of what you quoted:

Creating analogous heterojunctions between different 2D semiconductors would enable band engineering within the 2D plane

Which shows that they describe the full device including multiple atomic layers as a 2D plane.

Now the researchers obviously know that this is not a 2D device, in the same way that graphene researchers know that graphene is not 2D (put a gate dielectric and a gate on it and you have a very much 3D transistor). Except at least in graphene the transport is 2D, for the device is this paper there is vertical transport as well. These researchers are simply jumping on the "2D" buzzword bandwagon because it's a hot research topic.

I happen to dislike a lot of what the 2D folks are claiming in the media because they tend to make very hyped claims about their device performance. And most people understand that 2D materials are not really enablers for flexible electronics or transparent electronics because you can take humble silicon or other semiconductors down to similar thicknesses and achieve similar flexibility and transparency. Or you can make a really tiny silicon device that doesn't need to be flexible even when mounted on a flexible board. Flexible electronics is really all about packaging and interconnect (not to mention a killer app).

5 days ago
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How many devices are connected to your home Wi-Fi?

MattskEE Re:Why Fy? (260 comments)

I actually thought his maglight comparison was an excellent layperson analogy. In a crowded room I would be less unconcerned, although there may be several emitters, anything that is a reasonable distance away from you has been attenuated greatly by the spreading of the signal and spread out over a much larger portion of your body. I have not read the scientific literature but I would guess that the main area of interest for RF safety is the cell phone in your pocket since you could conceivably absorb a large portion of that phone's transmitting power over a fairly small volume of your body.

This does not apply to megawatt radars, or kilowatt microwave ovens, but to single watt phones/wifi there's not much to be concerned about.

about a week ago
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How many devices are connected to your home Wi-Fi?

MattskEE Re:Why Fy? (260 comments)

Sorry for the late response that you probably won't see. I could calculate some numbers, although getting an exact value is tricky because while with skin depth and antenna aperture you could relatively easily estimate the volume over which the RF power is dissipated into heat, I lack the background to calculate the rate at which heat will be conducted away and spread out. I'm sure that regulatory agencies have done this calculation.

You should really do some reading on the subject such as: http://www.durham.ca/departmen... (this is for Canada but from a quick google it seems informative, I'm sure there are similar US-specific references).

Anyway to give you an idea of a reasonable worst case, a typical phone or router will give off 1 watt maximum. Let's say for the sake of argument that you absorb all of that as a worst case (which you won't). Is that a lot? Not really. At about 4000 J/kg-degreesC for water it will take 160 seconds to heat one shot glass (40mL) of water by 1 degree C. During that time heat will be conducted away so you will likely see much less than a single degree temperature rise, which is safe.

If you want more detail there is ample scientific literature on the subject, but this back of the envelope calculation based on reasonable worse case conditions seems to show that the danger from RF emitters that are code compliant is negligible.

about a week ago
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Numerous Methane Leaks Found On Atlantic Sea Floor

MattskEE Re:Feedback loops (273 comments)

This is something where engineers know things that climate scientists apparently don't.

If the positive feedback was so strong, that the system was unstable (right half plane as it were) the earth would already be Venus. Doesn't stop climatologists talking out of the butts and proposing just such strong positive feed-backs.

TL;DR; Don't ask a climatologist a control systems question and expect a reasonable answer.

Real engineers know that reality is rarely a linear system represented only by poles and zeros. And they also know that complex systems can have multiple locally stable points, and that even stable systems may "ring" when perturbed with potentially catastrophic consequences.

Consider the humble electronic oscillator which most certainly has a right half plane zero, does its output rise over time until it blows up the universe (aka turns into Venus)? No it doesn't. And to describe the magnitude of the oscillation generally requires the nonlinear transistor model which includes things like the maximum output current of the transistor, it is not a simple linear model like the one you propose.

Earth is quite complex and while an engineer could model it as a control system it would be much more complex than the one you have proposed.

TL;DR Engineers are just as capable of being incorrect as climate scientists are.

about a week ago
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How many devices are connected to your home Wi-Fi?

MattskEE Re:Why Fy? (260 comments)

Now I would be extremely interested to hear why my comments would give you that impression?

None of the above reasons, only that you seem to be very concerned with low-level non-ionizing radio frequency fields which are not thought to be a health hazard.

If you want your visitors to leave phones at the door to enhance social interactions and if you don't want to use mobile devices indoors personally for the same reasons, that's perfectly okay though a bit unusual.

You get the crazy label though if you think that low level RF is a safety risk.

about two weeks ago
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Getting IT Talent In Government Will Take Culture Change, Says Google Engineer

MattskEE Summary misplaces emphasis on one point (166 comments)

Actually Mikey gives four reasons for the healthcare.gov problems, but the summary just focuses on the last one, probably because it sounds funny:

The original points (as summed up by me in a few words) were (1) Fragmentation of implementation, (2) Lack of monitoring of system, (3) Lack of experience by the companies building it, and (4) workplace culture clash.

about three weeks ago
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Harvesting Wi-Fi Backscatter To Power Internet of Things Sensors

MattskEE Re:Why use wireless power? (138 comments)

Yes and if you read their paper an RF switch is used to adjust the terminating impedance of this antenna which perturbs the reflectivity. That RF switch will consume a finite energy and power. It is an active component and not a passive component. A passive component would not accomplish the modulation.

I think it sounds reasonable that a reflector like this might be able to use less energy per bit than a conventional high-efficiency transmitter, since the RF power is being provided elsewhere, this is effectively just a modulator inserted between (or to the side of) the transmitter and receiver. However the study authors do not perform any theoretical analysis or measurement in their paper to support this notion.

about a month ago
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Harvesting Wi-Fi Backscatter To Power Internet of Things Sensors

MattskEE Re:Why use wireless power? (138 comments)

Although this device takes no internal power to cause the back scatter effect

That's incorrect, a switch always requires energy to change state, as well as a usually very small amount of power to maintain at least one of the two states. Quite a bit of a CPU's power dissipation comes from the energy consumed by CMOS switches switching from a one state to another.

It may well be that this is more power efficient than other methods of transmitting information but that has yet to be backed up by theory or demonstration.

about a month ago
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Harvesting Wi-Fi Backscatter To Power Internet of Things Sensors

MattskEE Re:iFind (138 comments)

It only works because it has a very low bitrate of 1kbps:

The UW’s Wi-Fi backscatter tag has communicated with a Wi-Fi device at rates of 1 kilobit per second with about 2 meters between the devices.

Although the authors claim that "The Wi-Fi Backscatter tags do not require any batteries and can harvest energy from ambient RF signals" they make no attempt to back up this claim with measured or estimated energy efficiency of this transmitter. The standard metric for high efficiency transceivers is joules per bit, because low bitrate communication always consumes less energy than high speed, but the only useful way to compare it to another high efficiency transmitter is to see if it can transmit a certain amount of data for less energy.

While I don't expect every paper to address every aspect of a technology, they should not then turn around and make baseless claims like "We believe that this new capability is critical for the commercial adoption of RF-powered Internet of Things." in a length 12 page paper that fails to address the one metric which would allow them to make such a claim.

about a month ago
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Nevada Construction Project Could Be Tesla/Panasonic Gigafactory

MattskEE Re:Headline trifecta (81 comments)

Competition is also good for business because it increases the total size of the market, increases availability and reduces costs from 3rd party vendors (batteries, motor drives, charging stations, etc), and reduces costs of specialized labor (eventually) by growing the labor pool of engineers who design electric vehicles.

Having a big part of a small market is not a good way to go. I think Elon's goal (in addition to any altruism on his part) is to grow the entire market and ecosystem for electric vehicles while holding onto a decent (but perhaps smaller) market share.

about a month ago
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Grad Student Rigs Cheap Alternative To $1,000 Air Purifiers In Smoggy China

MattskEE Re:Lots of people criticize this for its obviousne (182 comments)

Probably because he doesn't live in China.

This is China we're talking about, with 1.3 billion people. I'm sure that people have already strapped filters onto fans, this one guy just happens to be getting some feel-good-DIY publicity because he's marketing his product. Kudos to him because it seems like a good thing that he's doing this, but I would be amazed if this is actually considered novel in China.

about a month ago
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Grad Student Rigs Cheap Alternative To $1,000 Air Purifiers In Smoggy China

MattskEE Re:Lots of people criticize this for its obviousne (182 comments)

Are you sure about that? Other than this one article what makes you think that all or most Chinese citizens with air filtering fans were paying $1000 for them?

about a month ago
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Quiet Cooling With a Copper Foam Heatsink

MattskEE Re:Hmmm... (171 comments)

I agree that this doesn't pass the sniff test. A foam has a low ratio of metal to air, it's the cross-sectional area of the copper that allow vertical conduction of the heat from the heat spreader plate. This has little copper area so conduction is limited. It's further worsened by the random nature of the strands so the heat is conducted laterally as well as vertically and so the conductive thermal resistance is increased because the heat needs to travel a longer path.

So while I'm not saying it doesn't work, I suspect that this foam is more of a gimmick than a properly optimized heatsinking solution.

about a month ago
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Cable Companies: We're Afraid Netflix Will Demand Payment From ISPs

MattskEE Re:not likely (200 comments)

I get that the meteoric rise in online video streaming by customers puts pressure on ISPs because if affects the oversubsribe ratio that they can use (which is required to turn a profit) while still providing a good user experience.

But what I don't get is why you can possibly blame Netflix. Your customer requested 100GB from Netflix last month. Netflix supplied it based on your customer's request. If you think 100GB (or however much) data in one month is too much then throttle your customer, but do it fairly based on each customer's usage and don't play favorites with which companies you allow your customers access to. 100GB of Netflix traffic should be treated the same as 100GB of porn, or whatever else your customer is getting up to.

My university's residential internet connection started undergoing major strain several years ago, primarily due to online video. So they implemented traffic throttling. I don't remember the precise details, but it was along the lines of a daily 1GB of unthrottled data between 4PM-1AM after which speed was reduced , and no throttling from 1AM-4PM. This was a completely fair and balanced way of providing a pretty good user experience while limiting traffic during peak hours to avoid congesting the network.

about a month ago
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Verizon's Accidental Mea Culpa

MattskEE Re:I disagree (390 comments)

How does settlement usually work for unbalanced connections? My thought is that since the Verizon customers request data from Netflix servers, and Level 3 delivers that data to the Verizon network, then if anybody paid settlement it should be Verizon.

But since this is an everybody-wins situation (Netflix pays level 3, Customers pay Verizon, all customers are happy when the pipes run smoothly) then settlement free peering makes sense.

about a month and a half ago
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People Who Claim To Worry About Climate Change Don't Cut Energy Use

MattskEE Re:user error (710 comments)

I don't believe we can change global climate.

Not with that attitude you can't!

But seriously, we are the most powerful race on the planet, we use over 30 billion barrels of oil per year (over 1.2 trillion gallons). Nobody knows exactly how much oil there is, but as a rough estimate from a layman it seems likely that we could estimate that in less than a thousand years we'll have probably burnt over a million years worth of natural carbon storage, i.e. it is being released over a thousand times faster than it was stored.

To me that it as least suggestive that we as a species could have an effect on atmospheric CO2 concentration and through that global climate and ocean acidity.

about a month and a half ago
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$500k "Energy-Harvesting" Kickstarter Scam Unfolding Right Now

MattskEE Re:Thanks for the tip! (448 comments)

Do you understand that EM energy harvesting power will be directly proportional to size? It's not a matter of being a "miniaturization expert" it's a matter of physics and how much radiated WiFi power you can harvest with a given antenna aperture.

about 2 months ago
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How Vacuum Tubes, New Technology Might Save Moore's Law

MattskEE Re:Why are we saving a law? (183 comments)

Moore's Law has never been a law and nobody treats it as one.

It started off as an observation which happened to basically be correct. Then it became more of a roadmap, with industry using it to set technology targets and allocating R&D resources so that they can continue following Moore's "Law".

about 2 months ago

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