6,522 karma · joined March 21, 2012
Unless you specifically design for it (specifically, with a dummy load), the efficiency of the system is inversely proportional to its ability to do this. You need a secondary system.
The power system can connect the battery terminal to in or to out, so if you switch both on at once you effectively bypass the battery. It's called shoot-through current and is generally considered a destructive process. If you can switch on and off fast enough you could limit it to a non-destructive level, but in practice most systems will not switch fast enough. They are designed to operate with the battery load, which is at minimum ~10x higher resistance than the transistor itself. In practice it is often 100s of times higher.
That's where the efficiency comes into it. If a power system is 98% efficient (pretty normal- this does not include power lost to heat in the battery itself), that means the electronics can only burn 1/50th as much power as normally passes through the system. Worse, when you put the switch into shorted position it will try to pass 50x its rated current. You need to switch much faster -certainly more than 50x faster- and that will probably put it outside its operating region.
It is relatively easy to just have a large resistor, but it is not very well suited to use battery power systems. Batteries are very low impedance, and the power system exists to transform to a lower voltage and higher current. Resistors are cheaper when they are higher voltage, so the power system is a hacky kludge.
The overall solution is just more batteries. Oversupply is a transient problem and always will be.
It was Trump's 2017 Tax Cuts and Jobs Act, which amended IRS code.
Herpesvirus latency is really complicated, more so than HIV. It hides in more tissues and particularly in nerves, which have some degree (debated) of immune privilege. Every type has different latency. Most types have multiple, very different methods of staying latent and stay more latent than HIV. We understand some of those methods, partially understand many of them, and still don't know a lot about others. A latent infection will probably still remain if too few of these pathways are activated at once.
That stands in stark contrast to lung cancer, which has a median survival time of ~15 months. Pancreatic cancer usually kills you in less than a year. Colon cancer is better, but still only ~6 years. Leukemia and Lymphoma can occur in middle age or even in early childhood, and rob an entire lifetime.
That said prostate cancer is most of the time not a big deal. Getting prostate cancer will still probably the most dangerous thing that ever happens to you (how many single events have a 5%+ mortality rate? besides birth) and should be treated incredibly seriously, but the odds are still good you'll be fine.
Nope! Special class II is all the general class II requirements plus the special rules: https://www.fda.gov/medical-devices/overview-device-regulati...
Specifically in this case I chose this classification because the only difference is the alarm. Without an alarm or alert, you're normal Class II. The alert bumps you up to the special rules. A wearable device would have an alert.
> See the "clinical studies" section
I see where it says "clinical studies will not be needed for most arrhythmia detector and alarm devices [...] FDA will always consider alternatives to clinical testing when the proposed alternatives are supported by an adequate scientific rationale."
They recommend ANSI guidelines and standards for algorithms to measure ST length and for the electrodes. They don't even require following them. The clinical requirements are for all of the crazies who want to do crazy things like sell mood rings for heart attacks. It is very unlikely they would require a premarket clinical trial(NOTE that they allow many products to register as investigative!) for something like an apple watch.
Medical device regulations are a paper tiger. The effort in development is the concern- you can't register until the development is paid for, so if you're rejected then you've wasted all that money. Registering could be zero effort and that would not change. Especially for companies like apple, it is much more convincing that they are more concerned with patient lawsuits than problems with the FDA.
The LHC uses ~86 megawatts, about the same power as a 747's engine at full throttle. It's about the same as a small natural gas powered turbine. GE builds gas turbines that produce 800+ MW.
The LHC is just a controlled environment to study the kind of particle collisions that are happening all over the earth every day. We live next to a giant fusion reaction, and freak particles come in from outer space all the time. We have detected many particles with millions of times more energy than the particles in the LHC- the Oh-My-God particle had 20 million times more energy.
> Can someone tell me what the likelihood of a humongous explosion from nuclear fusion could be?
Fission self-sustains. Each reaction produces 3 neutrons that can start another reaction. It explodes because the neutrons grow like 3, 9, 27 etc.
Fusion does not. You have a number of atoms, and 2 of those atoms have to find each other to fuse. One reaction does not make any other reactions more likely. Unlike fossil fuels or fission reactions, the fuel cannot be lit. It can only burn when carefully confined. You can only build up enough flame to break the containment vessel, at which point it goes out. Since the inside of the vessel is basically a vacuum, it will implode instead of exploding.
There is no chance that early fusion plants will be small enough to justify building them in the same building as a factory. They will start large.
> For example, aluminum requires ~14-17MWh to produce 1 ton
The Hall–Héroult process runs at 950 C, just below the melting point of copper. It is close to twice the temperature of steam entering the turbines. It is not something that can be piped around casually- as a gas it will always be at very high pressure because lowering the pressure cools it down. Molten salt or similar is required to transport that much heat as a liquid. Every pipe glows orange. Any industrial process will effectively be a part of the power plant because of how difficult it is to transport that heat away.
Also NB that the Hall–Héroult process is for creating aluminum from ore, and recycling aluminum is the primary way we make aluminum.
They allow a summary report. They don't require a clinical human trial. They barely care if you follow the FCC and safety requirements for electronics in general. This does not look burdensome.
Men and women have slightly different ECGs and a doctor can usually tell your gender from an ECG. The appearance of a heart attack will be more similar than a normal heartbeat. Gender differences have a much smaller impact on an ECG than things like body mass and blood pressure. Overworked hearts will look more like overworked hearts.
Integrated frontends have had big impacts on efficiency and improving batteries have had basically the same increase in specific energy. I would be shocked if power was a limiting factor.
https://www.ti.com/lit/ds/symlink/ads1291.pdf?ts=17469713549...
More importantly, these techniques operate on the V1, V4 and inferior temporal cortex areas of the brain. These areas will fire in response to retina stimulation regardless of what's happening in the rest of your brain. V1 in particular is connected directly to your retinas. While deeper areas may be sympathetically activated by hallucinations etc, they aren't really related to your conception of things. In general if you want to read someone's thoughts you would look elsewhere in the brain.
Not onto known images, onto latent spaces of existing image networks. The recognition network is getting a very approximate representation which it is then mapping onto latent spaces (which may or may not be equivalent) and then the image network is filling in the blanks.
When you're using single-subject, well-framed images like this they're obviously very predictable. If you showed something unexpected, like a teddy bear with blue skin, the network probably would just show you a normal-ish teddy bear. It's also screwy if it doesn't have a well-correlated input, which is how you get those weird distortions. It will also be very off for things that require precision like seeing the actual outlines of an object, because the network is creating all that detail from nothing.
At least the stuff using a Utah array (a square implanted electrode array) is not transferrable between subjects, and the fmri stuff also might not be transferrable. These models are not able to see enough detail to know what is happening- they only see glimpses of a small section of the process (Utah array) or very vague indirect processes (fmri). They're all very overfitted.
Well, not the same reason. Shear strength is in many ways more important because failure usually propagates from an origin like a rip- by shearing.
But fundamentally, tensile strength and shear strength are both much more empirical than compressive strength. Tensile strength can be used with ~99% accuracy on a wire that is microns long or miles long. If you double the relative width of a testing sample it will dramatically change the measured compressive strength even without buckling.
There also is no such thing as strength per volume.
Titanium is a pretty bad comparison. Its 10-20x weaker, and is also weaker than fiberglass, nylon, most steels, sapphire, many other types of metals and fibers...
> The tensile strength of discrete volumes of limpet tooth material measured using in situ atomic force microscopy was found to range from 3.0 to 6.5 GPa
Also "compressive strength" is not really a thing, in that it's only a metric that is useful for practical applications. It's proportional to tensile strength, and unlike tensile strength it does not generalize well to things like modeling stress. Tensile strength is a much more fundamental quality than compressive strength.
Strength of a material is force per area. In ideal terms it is measured over an infinitely short length; if you measure over a long distance then the sample is stretched and becomes thinner, changing the measurement. If you test on a shorter and shorter sample you get closer and closer to the ideal value.
The same is not true for compressive strength tests. If you measure compressive strength by pressing on a very very thin disc of material it will just resist all force; it has effectively infinite strength. The actual failure mode of compression is always tensile strength in the radial direction, or buckling or something. You press the sample and it stretches sideways until it exceeds the sample's tensile strength in that direction. The shorter the sample is, the less it can expand radially and the stronger it appears to be. There is no "ideal" compressive strength, only useful test setups.
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5219933
> Our main finding is that AI chatbots have had minimal impact on adopters’ economic outcomes. Difference-in-differences estimates for earnings, hours, and wages are all precisely estimated zeros, with confidence intervals ruling out average effects larger than 1%. At the occupation level, estimates are similarly close to zero, generally excluding changes greater than 6%.
> Indeed, the reported productivity benefits were modest in the study. Users reported average time savings of just 2.8 percent of work hours (about an hour per week).
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5219933
> Our main finding is that AI chatbots have had minimal impact on adopters’ economic outcomes. Difference-in-differences estimates for earnings, hours, and wages are all precisely estimated zeros, with confidence intervals ruling out average effects larger than 1%. At the occupation level, estimates are similarly close to zero, generally excluding changes greater than 6%.