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Comment: Re:"You ate the poison mushroom!" reflex. (Score 1) 154

It's when I'm bending, twisting, picking up objects, etc. that I get vertigo.

Which is what's expected. You spend most of your time upright, so your brain gets a lot of experience with the chaged response of your inner ear. So it learns to interpret the modified signals more appropriately.

But when you bend down, twist, pick things up, and otherwise get into rarer positions and motions, you're in a set of conditions where the signals you're getting are not what the brain has yet figured out. Meanwhile, some of these postures also make you lose many of the visual cues of your position, throwing you into dependence on your muscle and (defective) ear signals. Bingo: Vertigo attack.

You MAY be able to reduce the amount of severity of the attacks by doing such postures as exercise, to help you learn to map more of the range of your ears' signals. Assuming, of course, you can stand the vertigo while doing the exercises, and/or can stop before the attack gets very strong.

Comment: Re:Which is why FAST flicker still causes vertigo. (Score 1) 154

Electronic ballasts don't run at line frequency, they are many times higher (1,000hz+), so that issue should be eliminated.

Electronic ballasts may indeed produce thousands of flashes per second. But they're powered by a "raw" power supply - a recitfier and filter capacitor that is in turn powered by the line, which comes and goes 120 times per second (or 100 in much of Europe).

If the filter capacitor is large enough that it doesn't discarge appreciably before it is recharged by the next half-cycle, the individual pulses produce about the same amount of light, the repitition rate of the pulses is close to constant, and thus the average brightness is close to stable over the line power cycle.

If the filter capacitor is smaller, it discharges substantially during the low-voltage parts of the cycle. The individual flashes get dimmer when the voltage droops and the repititition rate may also change. The average across several consecutive mini-flashes tends to track the input voltage.

If the capacitor is still smaller, the voltage may go so low that the high-frequency oscillator actually stops during the low voltage parts of the input cycle. The flicker may actually become substantially WORSE.

Bigger capacitors cost more. So guess what the cheap, commodty, lamps get.

Comment: Re:Evolution (Score 1) 253

by Bruce Perens (#47485313) Attached to: New Treatment Stops Type II Diabetes

:-)

You make it sound like starving people are getting fat too.

If they are becoming obese, the particular individual has a surplus of caloric intake, if only for this year or month. This is not to say that they have proper nutrition. So I am not at all clear that the fact that there is obesity in the third world is confounding evidence.

Comment: Wait until you're older. B-b (Score 2) 154

There are two sets of muscles for eye movement - one for convergence, which rotates the eyes, the other for focus, which reshapes the eyes...

The latter system also reshapes the lens.

Unfortunately, as you age your lenses stiffen up and/or the muscles get weaker, and that system gradually degrades. (This "disease of age" (presbyopia) becomes significant pretty early - about mid 30s.)

(By the way: The eye rotation is actually THREE axis, although the motion around the line-of-sight is pretty limited. {Look in a mirror and rotate your head right-left to see it.} Apparently evolution found matching the image rotation by slightly rotating the eyes to be less expensive than a layer of image-rotation logic in the brain.)

Comment: Which is why FAST flicker still causes vertigo. (Score 5, Interesting) 154

I find that any kind of response time lag between my inputs and the real world, especially when it varies, is what makes me sick ...

My wife has vertigo. Her attacks can be triggered by fluorescent or high-pressure arc lights where the flicker rate is above the flicker-fusion rate of the eye. (This makes trips to warehouse stores problematic - they have to be short or she'll be down for the rest of the day. That's hard at, say, Costco.)

I used to wonder how this could be, and finally realized that the "strobe light" effect produces small, but significant, errors in observed position of the background items (shelves, etc.) that she uses for reference to balance despite the damaged inner ear.

When they first began using fluorescent lights in factories - in the days before guards over moving machinery were common - the worker injury rate went 'way up. Turns out the lights made the AC-powered motors, turning at or near an integer fraction of the line frequency, look like they were stopped or only moving slowly.

The fix was to build the light fixtures in two-tube versions, with a capacitor and an extra inductor in the balast, so the "lead lamp" and "lag lamp" would light at a quarter-cycle offset. In combination with suitably persistent phosphors this made them largely fill in each other's dim times, enough to make fast-moving parts blur and look like they were moving. For large arc lights, a similar fix was to arrange them so adjacent lamps were distributed among the three phases of the power feed, rather than having rows or patches of lights all flickering in unison.

Unfortunately, this lore has apparently been lost - at least outside the specialists wiring factories full of moving parts. Warehouse stores have rows and sections of arc lighting all wired to the same phase. I'm not sure, but I don't think the new electronic ballasts for flourescent lights do the lead-lag thing, OR have enough raw filtering capacitance to power the lamp through the phase reversals. (And then there's LED lamps...)

It's not a safety hazard these days, now that OSHA rules have all the fast-spinning machinery covered with guards. But for those with vertigo it's a big problem.

Comment: "You ate the poison mushroom!" reflex. (Score 4, Informative) 154

The human body has three systems for balance - Inner ears (3-axis accellerometers and "rate gyros"), visual modeling, and muscle/tendon position & stress sensors - and needs any two to balance, stand, and walk properly.

It also has a reflex: When two of them disagree (particularly visual vs. ear), it is interpreted as "You just ate a neurotoxin! Get it out NOW and we MIGHT survive it!"

Thus nausea, projectile vomiting, explosive diahrrea, and clothes-soaking sweating if the mismatch is strong. If it's smaller - nausea. ("Whatever you just ate may have been toxic or spoiled. So you're not going to like it anymore.")

Of course other things than being poisoned can trigger it:

Diseases that temporarily incapacitate or permanently damage the inner ear are one class. (For instance, Meniere's Disease, where the pressure-relef valve for the inner ear sticks, the pressure rises, and the membranes with the sensory nerves tear. Result: Sudden extremem vertigo attack - hours on the floor - followed by days or weeks of gradually reduced incapacity until the brain maps out the change to the ear - followed by another tear and repeat indefinitely. Very high suicide rate.)

Vechicles, where you may visually fixate on the accellerating inside rather than the surroundings, are another: Cars, boats, ariplanes (and the corresponding car/sea/air sicknesses) are notorious, as are carnival rides and trains. For relief, make a point of looking at the horizon or otherwise the exterior. Eventually the brain may learn "I'm in a vehicle. Ignore the weird signals from the ears. (That's why vertigo sufferers may NOT have attacks in MOVING vehicles...)

And, of course, VR mismatches - to the point that there is a term of art: "Barfogenisis" (I hear the lengths of some of the rides at Disneyland are calibrated so they end and the crowd is out into the hall just BEFORE the effect would become pronounced.)

Comment: Evolution (Score 1) 253

by Bruce Perens (#47480445) Attached to: New Treatment Stops Type II Diabetes
For most of the existence of mankind and indeed all of mankind's progenitors, having too much food was a rare problem and being hungry all of the time was a fact of life. We are not necessarily well-evolved to handle it. So, no surprise that we eat to repletion and are still hungry. You don't really have any reason to look at it as an illness caused by anything other than too much food.

Comment: Re: If you pay... (Score 1) 15

Martin,

The last time I had a professional video produced, I paid $5000 for a one-minute commercial, and those were rock-bottom prices from hungry people who wanted it for their own portfolio. I doubt I could get that today. $8000 for the entire conference is really volunteer work on Gary's part.

Someone's got to pay for it. One alternative would be to get a corporate sponsor and give them a keynote, which is what so many conferences do, but that would be abandoning our editorial independence. Having Gary fund his own operation through Kickstarter without burdening the conference is what we're doing. We're really lucky we could get that.

Comment: Re:One hell of a slashvertisement! (Score 1) 15

I think TAPR's policy is that the presentations be freely redistributable, but I don't know what they and Gary have discussed. I am one of the speakers and have always made sure that my own talk would be freely redistributable. I wouldn't really want it to be modifiable except for translation and quotes, since it's a work of opinion. Nobody should get the right to modify the video in such a way as to make my opinion seem like it's anything other than what it is.

Comment: Re:If you pay... (Score 2) 15

Yes. I put in $100, and I am asking other people to put in money to sponsor these programs so that everyone, including people who did not put in any money at all, can see them for free. If you look at the 150+ videos, you can see that Gary's pretty good at this (and he brought a really professional-seeming cameraman to Hamvention, too) and the programs are interesting. Even if at least four of them feature yours truly :-) He filmed every one of the talks at the TAPR DCC last year (and has filmed for the past 5 years) and it costs him about $8000 to drive there from North Carolina to Austin, Texas; to bring his equipment and to keep it maintained, to stay in a motel, to run a multi-camera shoot for every talk in the conference, and to get some fair compensation for his time in editing (and he does a really good job at that).

+ - Open Hardware and Digital Communications conference on free video, if you help->

Submitted by Bruce Perens
Bruce Perens (3872) writes "The TAPR Digital Communications Conference has been covered twice here and is a great meeting on leading-edge wireless technology, mostly done as Open Hardware and Open Source software. Free videos of the September 2014 presentations will be made available if you help via Kickstarter. For an idea of what's in them, see the Dayton Hamvention interviews covering Whitebox, our Open Hardware handheld software-defined radio transceiver, and Michael Ossman's HackRF, a programmable Open Hardware transceiver for wireless security exploration and other wireless research. Last year's TAPR DCC presentations are at the Ham Radio Now channel on Youtube."
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