Science and Technology | John Clarke Online

How Does Your Rebreather Scrubber Handle the Deep?

If you’ve planned a deep dive, to say 100 meters or deeper, you may have wondered just how your rebreather scrubber will handle that depth. Since pressure is equalized across a carbon dioxide (CO₂) absorbent canister within a rebreather, it won’t implode. But what about the chemical absorption reactions occurring within the scrubber?

The rebreather scrubber is a vital part of your underwater life support system, so that question is a pretty important one. And the answer is very hard to find.

I recently traveled to Ireland to act as an external examiner for a Ph.D. student’s Doctoral Dissertation defense in the Department of Mechanical, Biomedical, and Manufacturing Engineering of the Cork Institute of Technology. The very talented graduate student was Shona Cunningham, and her dissertation was titled, “Carbon Dioxide Absorption and Channeling in Closed Circuit Rebreather Scrubbers”. She’s an athlete, musician, and perhaps most importantly for you readers, an avid diver.

Her work is the first computational fluid dynamic representation of scrubber canister thermokinetics. A portion of her dissertation work has already been published. Apparently, it was partially inspired by some of my computer simulation descriptions posted on this blog, which can be found here, here, and here.

Dr. Cunningham’s analytical approach (using Ansys CFX) showed that ambient pressure (depth) could reduce the effectiveness of scrubber canisters. In support of that finding were the words from the Dive Gear Express website regarding the Diverite O2ptima using the ExtendAir scrubber cartridge.

“As pressure increases the total number of molecules, the relative concentration of CO₂ molecules in the loop is reduced, slowing the chemical absorption process. Thus as depth increases, scrubber efficiency will decrease.”

The U.S. Navy has no experience with the Diverite O2ptima, but they have information on other rebreathers using granular absorbent. That experience shows that there is no reliable depth effect across all rebreathers and all absorbents.

U.S. Navy MK 16. US Navy photo by Bernie Campoli.

For example, in one rebreather there was indeed a 17% decrease in endurance using large grain absorbent (Sofnolime 408) at 50°F in descending from 190 fsw to 300 fsw (58 to 92 msw) breathing air. However, there was no decrease in duration when using fine grain absorbent (Sofnolime 812) under the same conditions. (On an actual dive, air would never be used at 300 fsw, but air was used in this study for scientific reasons.)

In another rebreather using Sofnolime 812, for a change in depth from 99 fsw to 300 fsw (30.3 to 92 msw) there was a 29% increase in duration at 75°F, a 10% increase at 55°F, and a 15% decrease at 40°F. Although air diluent was used at 99 fsw, 88/12 heliox diluent was used at 300 fsw.

From another manufacturer, I obtained information on two of their rebreathers. At 4°C, 1.6 L/min CO₂ injection rate (corresponding to a fairly heavy work rate), 40 L/min ventilation rate using air diluent, there was a 27% decrease in one rebreather in going from 15 to 40 msw (50 fsw to 132 fsw), and a 11% decrease in another of their rebreathers in dropping from 40 msw to 100 msw.

In another rebreather tested under the same conditions except for depth, the canister duration dropped 39% between 15 and 40 msw.

So, there is some support for a drop in duration with depth, but in other cases, there is either no effect or an increase in duration with deeper depths. Clearly, if the high number of inert gas molecules coming with a pressure increase makes it more difficult for CO₂ to reach absorption sites, then that would be a simple and unavoidable fact of physics. But that cannot be the whole story. What is likely to be going on, a hypothesis, is being developed for a later posting.

Should the effect of depth on your particular rebreather matter to you? Logically it shouldn’t. Even on a deep dive, the majority of the dive time is spent shallow, decompressing.

However, consider the case where you conduct a deep dive with an anticipated short bottom time, but something bad happens on the bottom. You or your dive team becomes fouled, ensnared in lines. Or there is a partial cave collapse trapping you. The benefit of a rebreather over scuba is that it gives you time to sort out your problem. Gas consumption is not nearly as great a concern as with open-circuit breathing apparatus.

However, as the minutes tick by as you work deep to get yourself or a team member free, you might wonder, “How is my scrubber handling this depth?” In the middle of a crisis is no time to be making assumptions about the status of a major part of your life support system.

Ask your manufacturer how your canister performs at depth. You have a right to know, and that information just might prove useful someday.

The Positive Side of Internet Data Gathering

There is a good reason why God and aliens (of the extraterrestrial variety) use telepathy to communicate. It is the only secure form of information transmission. Everything else is subject to capture, storage, and retrieval.

There is currently a frantic paranoia spawned by national and international agency’s collection of virtually everything we say and do. The only thing not open for capture are our thoughts and dreams, at least for now. (Yes, the Army’s working on that).

But governments aren’t alone in information spying — commercial industry is perhaps outpacing governments in their data collection efforts. Their motivations may be different, but the frenetic pace and implications are every bit as invasive. Privacy, as we’ve known it, is dead.

I’ve previously written about Google Noodling , which is a way of catching Google in their data-mining efforts. And like the tone of that article, you have to take a lighthearted view of such efforts. It is not going away. And if we don’t “get over it”, we may, in my estimation, go a little crazy.

But there is a positive side to all this, and a large and growing number of people are finding this side to be personally satisfying. That has to do with family connections, or genealogy. I’ve written about that topic as well.

Scan20080_1 crop — My brother and I. He was five years older.

Last night I solved a very personal family puzzle through the help of Ancestry.com. Both my parents had brown hair and brown eyes. Both their younger children, sons, had blond hair and blue or green eyes.

I’ve spent a lot of time of late with my brother before he passed from a prolonged illness, and I was struck as never before with the purity of the blue color in his almost iridescent eyes. (I’m the one with the green eyes.) When young, both of us had blond hair, which eventually darkened with age. My brother was tall and thin. I was thin, but vertically challenged.

In the next generation, both my children have green eyes, perhaps because I married a green-eyed girl. Our daughter has blonde hair, and even a granddaughter has greenish-brown eyes. And a new grandson baby seems to have blue eyes and blond hair.

I have never ceased wondering, as did my parents no doubt, where those light colors came from. Having believed strongly in my mother’s fidelity, I kept assuming that someday I would discover the source of the blue/green eyes and blond hair.

That happened last night, thanks to the technology of digitization and data mining. I discovered a World War I selective registration document from my Grandfather who died in a hotel fire many years before my birth. At the age of 34 he had blue eyes and “light” hair. He was both tall and “slender”, pretty much a perfect description of my brother.

The next morning I was able to go through unidentified family photos, and there he was, identified at last, the Grandfather I never knew. So apparently it wasn’t the mailman after all!

Obviously this discovery is of interest to no one except my cousins and other relatives. However, it does point out the value of computers, computer databases, and the sharing of information that large databases make possible. There is a tangible reward, for both the company providing the product (the database) and the customers who benefit from the data shared.

I’m sure that when my Grandfather filled out his draft card in 1918, he had no idea that the digital image of that card would end up in the hands of his unborn grandchildren and great grandchildren 95 years later.

Which makes me wonder, what will the world know about each of us 100 years from now? We’ll be long gone, but the record of our existence will survive somewhere in the depths of a digital storage facility. Without a doubt our descendants will enjoy reading about the inane things which pleased or troubled us in 2013, and which we so freely posted thinking that no one was listening, and no one really cared.

Believe me, some people will care. And apparently, everybody’s listening.

Phytophotodermatitis and the Fig Tree from Hades

My fig tree is a diabolical, horticultural menace sprouted from a demon seed. I’ve tried to kill it, but it won’t die.

In general, I love trees, and figs, but this particular fig tree (Ficus carica for the Latin purists out there) has sorely offended me. It has attacked me, causing, as they say, bodily harm.

Fig Tree from Hell crop — My fig tree shortly after its attack. Looks innocent, doesn’t it?

And to top that, it doesn’t even produce edible figs. Some people call them goat figs, because only goats are undiscriminating enough to eat them. I’m guessing any goats eating my figs will be cursed — for eternity.

The conflict began like most conflicts, with an innocent encounter. I was using a water hose to tunnel under a concrete slab to install a 3-inch diameter drainage pipe. I then inserted a five-foot long piece of pipe. So far, so good.

But I decided I needed to replace that pipe with a longer, more flexible pipe, which promptly got stuck in the hole. Looking into the tunnel I’d made I saw that some relatively small roots were now in the way. I cut them with a lopper and then blindly inserted my left hand into the hole to help pull the pipe through.

It was a tight fit, and the back of my hand was grinding into the sand and the cut ends of the roots as I tussled with the pipe and finally pulled it through the hole. There was no pain associated with the sandpapering of my hand. But, as I later realized, I was grinding something toxic into the skin.

The next morning I looked at an irregular shaped red blotching on the hand. I assumed that the sandpapering from grinding against the sand grains had irritated the skin. But as time went on, the discoloration got worse, not better. A physician friend recommended a combined antibiotic and topical steroidal ointment, and bandages to protect the irritated skin. Dutifully applied for several days, that treatment resulted in absolutely no improvement. In fact, the discoloration seemed to worsen.

I continued to work on the drainage project outside, and, as it turned out, sun light seemed to make the discoloration worse.

A week later when irregular shaped blisters erupted, I realized that my skin had reacted to something in the sand, and the most likely candidate was fig tree sap from the roots I’d cut moments before inserting my hand.

The Internet revealed that fig tree sap was highly irritating to human skin. In fact, it appears to be an effective chemical weapon.

One Week Blisters — Warning: when magnified this looks pretty gross.

Quoting from AllAllergy.net, “Phytophotodermatitis is an acute skin reaction that may be easily confused with other causes of contact dermatitis. It is characterized by sunburn, blisters, and/or hyperpigmentation. The reaction takes place when certain plant substances known as psoralens, after being activated by ultraviolet light from the sun, come in contact with the skin. This report describes phytodermatitis due to contact with figs. (Watemberg 1991)”

Amazingly, the discoloration of my hand is still visible 6 weeks after the insult. But, I’m happy to report, that fig tree is not; visible that is. It was cut low to the ground. Eerily, it’s toxic sticky sap continuously coats the stump, so apparently that bedeviled fig tree is not entirely finished with its mayhem.

That sappy stump will, no doubt, be plotting a comeback this winter, out of pure botanical meanness. But I am firmly set on a plan of containment. Only time will tell whose chemical weapons are the more effective, the tree’s or mine.

Strangely, my war with the fig tree got me to thinking about art censorship. It’s true.

Most art devotees are aware of the stylistic device of placing a sculpted fig leaf in a strategic location to disguise the anatomical humanness of otherwise manly looking gods or athletes. Apparently, this form of censorship was foisted upon the art world by powerful religious prudes of the Enlightenment.

Two Weeks Fig Sap — Two weeks after exposure to fig sap.

Well, as I sulked about my long-lasting dermatological insult, I got to wondering; why would anybody even think of putting a fig leaf anywhere near what is arguably a sensitive part of the human body?

I strongly suspect that the artisans would not have deliberately incorporated fig leaves as part of their design, because they probably knew all too well just how irritating fig leaves can be.

I imagine Adam and Eve were both made rather uncomfortable by their leaves. Perhaps that was part of God’s revenge for their disobedience. Makes me wince to think of it.

But I digress. This current horror story ends like most horror stories; the foe fig is vanquished at the end. But just before the ending credits role, you catch a glimpse of the fig tree stump, still pulsing its hellish chemical weapons, and not at all fully dead. For all I know, it may already be planning its sequel, where it turns really nasty.

Lesson learned: I’ll be waiting for it, with gloved hands next time.

Last Man Standing

It seems ironic that at the same time that equality of the sexes in marriage is being heavily promoted, there is a scientific announcement that the male of the human species is anything but equal; we are genetically weak. According to at least one female scientist, human males are destined to die out due to the fragility of our single Y chromosome.

This grave announcement comes from none other than the aptly named Professor Graves, of Australia.

Her forecast got me to thinking; what if I was the last human male on Earth. What would life be like?

My first naive, and probably delusional impression was that I would inevitably become a hot item. It really wouldn’t matter what I looked like; I would be desirable simply because of my rarity.

Which, if true in a fantasy sort of way, could actually be a nightmare. I would surely not be attracted to ALL females. I mean, that covers a pretty wide territory. The human population is pretty diverse.

However, once you become that unique of an entity, perhaps your free will may go out the window. It may not matter what I want. For instance, becoming or remaining paired with a single lady, remaining monogamous, might itself become a fantasy.

But as I delved a little deeper into this musing, another possibility presented itself. A world without men could only exist if scientists figured out a way to keep the population going without men. I suppose it’s possible, in an artificial sort of way. So what would I be then?

Well, perhaps nothing more than a freak, a rare oddity with a bizarre anatomical abnormality. Is it reasonable to expect genetic deviants to be in great demand by the ladies? I think not.

So, I hope that the scientist who claims that men may die out due to their chromosomal vulnerabilities is wrong. If not, the psychological outlook of that declining population of manly men would probably be bleak. And certainly, if by accident of birth I were the last man standing, my life experience might be every bit as challenging as it is for those with rare congenital handicaps.

Knowing that, I feel sure that if the scales of male/female birth ratios begin tipping away from the current normality, some male-dominated government will fund extensive research aimed towards preserving the status quo. Ironically, the answer to whether that research would be fruitful or not, might already be written in our genetic code.

As they say, only time (five million years by Professor Graves’ estimate) will tell.

I am Neanderthal, Pt. 2

The gleam in my father’s eye came in 2013. That is when it all started for me, years before my birth. I am more than a little annoyed by that.

In my searching of the archives trying to learn of my roots, I came across a 2013 article discussing the debatable morality of recreating the Woolly Mammoths through genetic tinkering. It would be immoral, was the scientist’s opinion.

So, how do you think that makes me feel, the only Neanderthal on Earth? No one bothered asking my opinion.

Morality, I think, is based on the profit motive; on hidden agendas. It is arguably immoral to create a solitary herd animal when there is no financial reward for creating an entire herd. A herd animal is lonely without a herd. I know; I am a herd animal too, in the strictest sense. If there was financial gain involved, I can guarantee you a herd would reappear, like magic.

Other than a tourist attraction, what could the incentive be for creating a herd of mammoths? The novelty would quickly wear off, I’m sure.

At least it did for me. The curiosity and wonder I invoked in the public as a child began to wane as I grew ever more body hair, and began to assert my independence, and hormones. Quickly I became yet another difficult, and apparently not very attractive, adolescent. I was seen as boring; old news.

But curiously, at the same time the morality of creating a single previously extinct herd animal was being discussed, the Russians uncovered liquid blood from the underbelly of an ice-bound Mammoth. Almost immediately, that miraculously preserved blood became a siren of inescapable beauty to geneticists. The most pious of them wondered, so I read, why God would reveal this magic pool of genetic mystery after so many millennia if in fact humans were not fated to recreate the Mammoth.

And almost in the same breath, Neanderthal. After all, Mammoths and Neanderthal are forever linked through folklore, originating in the cave art of my ancestors.

mammoth hunters — Mammoth Hunters: from arthursclipart.org.

Which brings me to a dream I had. It is true that supposedly primitive people put stock in dreams; but I digress.

I dreamed that Armageddon came suddenly, with nuclear weapons unleashed from Iran, Israel, North Korea, Russia, China, and the United States. It was horrifying, and true to prediction a nuclear winter ensued. Virtually no humans survived.

But there were survivors who actually thrived in the dark and cold. They were a large band of us Neanderthals who had been bred in secret locations in Siberia. After the holocaust, we Neanderthals were able to escape and pillage the remains of a devastated Earth.

And once again, herds of recreated Woolly Mammoths were also released in Siberia and fell prey to our kind, once again providing us sustenance.

Unwittingly, geneticists had secretly and unwittingly ensured the survival of a race of hominids, not exactly human, but close.

When the surviving humans and Neanderthals met, there was once again romance in the air. Beggars can’t be choosers when genetic survival is at stake.

But like I said, it was only a dream. I’m sure it could never really happen.

Could it?

To be continued.

I am Neanderthal

neanderthal-human-456 — CREDIT: Neanderthal Museum (Mettmann, Germany)

I suppose it was inevitable that I would be different; the ultimate “n” of one, the rarest species in the universe, the only Neanderthal on Earth.

By human standards I am very spiritual; I can remember my time before incarnation. I was told that I would be given a unique opportunity to excel in this lifetime. Of course, I had no idea what that truly meant. But there are no “do-overs” in life. I’m stuck for as long as I am here; so I might as well make the best of it.

Since no one knows how long Neanderthals live, I’m starting my memoirs now, at age 25. This way, if some violence or illness claims me, I’ll leave behind a record of what some would call a curious life. But it’s the only life I’ve known.

It all began in March 2013 when my ancestral genome was completely identified. Far as I can tell, that work was only a matter of curiosity. Actually, I would classify it not as curiosity but as mischief.

They tell me I was born in 2018. My earliest memories are of being tested and prodded. My body’s supply of blood has been withdrawn at least 10-times over, finding a home in just about every laboratory in the world.

You’re welcome.

I never signed a consent form for that testing, but apparently I have no more rights of consent than any other non-Homo sapiens. I am, apparently, guinea pig.

IQ tests seem to be of particular interest to academic scientists. There is a never-ending line of psychologists trying their particular flavor of IQ test on me. But the truth is, I am Neanderthal, not Homo sapiens. As someone once said, “A cat is a genius at being a cat.” I am a genius at being Neanderthal. I am the smartest one there is.

I have been asked what I think about the “Caveman” videos. Well, my ancestors, like yours, lived in caves; that’s true I suppose. However, the caricatures I see are as repugnant to me as blackface is to an African-American. Enough said.

As an adolescent I was constantly pitted physically against older boys. I’m proud to say I whipped their butts; every single one of them.

Starting at age 14, the U.S. Army began running me through endurance and strength tests. They found my limit, for sure, but never told me how I compared. But I did overhear someone in a grey suit once say, “We need lots more like him.”

I guess that means someone likes Neanderthals.

Speaking of liking, I’ve often wondered if I’ll ever find a girl. They tell me that humans and Neanderthals once interbred, but based on my experience, that seems highly unlikely now. Besides, who would fall in love with a guinea pig, even a well-endowed guinea pig. I am, after all, not human.

At least, that’s what they keep telling me.

To Be Continued

The Dinosaur in the Window

Child-Looking-at-Dinosaur-Through-Window--61512 — Result of a FreakingNews Photoshop contest. Image credit: Matro1. Click for original link.

Even a child can appreciate the strangeness of watching the broad, glistening side of a dinosaur lumbering past the bedroom window. Fortunately the creature paid me no heed; it didn’t pause to look in the window, just kept moving on, quickly disappearing from view.

I lay there, frightened I suppose, but all I remember in detail very many years later is the remarkable sight of that moving mass of ponderous flesh. I didn’t see its head or its tail, just its massive hulk of a body sliding along the side of the house as close as could be without touching the house wall, or ripping off the roof. I sensed somehow that the dinosaur was not carnivorous; likely a plant eater, perhaps a brontosaurus, and thus no immediate threat to me.

I frankly cannot tell if that image was a flash of a dream, or a waking hallucination.

I was maybe seven and much more interested in cowboys and Indians than dinosaurs. I was not a toy dinosaur collector, and neither were my friends. In fact, I think this was long before kids, or adults, knew enough about dinosaurs to be fascinated with them. And yet there it was, gliding quietly and smoothly past my bedroom window.

That image lasted maybe four seconds, and yet those four seconds have lasted a lifetime — literally.

If my brain is at all typical, then it seems to me that visual images occurring spontaneously and transiently in six and seven year olds are perhaps associated with a growing and rewiring brain. However, as an adult my most remarkable memories are of similar dreamlets, extremely vivid dreams lasting but a few seconds, just as did the imagery of the dinosaur walking past the window.

Due to my being an adult I can’t explain them by remodeling of my brain. So perhaps there is something unique about them that has nothing at all to do with age.

They are certainly varied, and seem to have nothing whatsoever in common with my actual life. For instance, one dreamlet was of launching off a tall spire in a crystal city, and gliding on wings in an obviously nonhuman form, in a non-Earthlike place. That was probably the strangest, and yet most interesting five seconds of my life.

Another dreamlet, hypnagogic in that I was falling asleep, lasted maybe only a second. In it I clearly saw a white car veer directly into the path of my car, and what had to be an unavoidable head-on collision.

For some time I was on the lookout for white cars (Do you have any idea how many white cars there are?), but years have passed since then and I am still very much alive.

I’m well aware that no one wants to hear about someone else’s dreams, unless they’re being paid to do so. But that is not what this writing is about. Instead it’s about the strange events called dreamlets, moving images that pop into our heads when we are not concentrating on anything in particular.

I suspect we all have them, but due to their brevity few people talk about them. They really aren’t open to interpretation, at least in the same manner as more prolonged dreams which have been interpreted by psychoanalysts like Jung and Freud, and a host of modern day analysts.

Arguably, the most modern discussion of these dreamlets is by Professor Charles Tart who has built a world-wide reputation on such matters. And yet he, like me, is reduced to only asking questions. In a recent blog posting he mentions a few potential explanations for dreamlets, some of which would be considered bizarre by most readers, but admits that none of them seem to match his experiences completely.

What interests me about his writing, however, is the fact that what he experiences during meditation and what I’ve experienced spontaneously share points in common. That leads me to believe these events are generalized throughout the human population. In other words, you may remember events similar to the dinosaur passing by your window, and may wonder what that was about. This posting, then, is to tell you that you are not alone. Unfortunately no one has authoritative answers for you.

If you have an interest in learning more about these brief events, then you may find Dr. Tart’s blog stimulating.

http://blog.paradigm-sys.com/where-do-all-those-images-and-dreamlets-come-from/

The Google Generation and College Life

I was recently reminded that almost everyone who is literate and has access to a computer and Internet connection has used Google to find something of interest to them.

The way I was reminded of that was from Google Analytics which gives me feedback on this blog. Over a period of a few days I witnessed a curious rise in the number of hits on a tongue-in-cheek description of a faux energy company (Cosmic Capacity Corporation) that purportedly sells personal black holes.

http://johnclarkeonline.com/2012/09/23/frequently-asked-questions-about-personal-black-holes/

Typically, the draw of a sample of my dry humor is low. So why should there be a rapid uptick in interest?

Well, I’m just as mindful of national security as the next person, so as I witnessed the first wave of unexpected interest my thoughts were that bad people were trying to expand their knowledge of potentially dangerous devices. After all, anything that could make most anything disappear, and if detected, evaporate itself beyond all trace of detectability must be of interest to criminals.

But whoever they were, they weren’t stupid: they caught on quickly that the posting was a ruse. Stay time was approximately 30 sec.

However, over the period of a week, the numbers continued rising, and then fell just as quickly back to their normal near-dormancy levels. Something strange was going on.

Capture2 — A Gaussian curve-fit to the Google Analytics data, January 20 – 28, 2013.

The limited data I have points to a total of 333 hits occurring with an approximately Gaussian (normal, Bell-shaped curve) frequency between January 21 and 27.

With that realization, I may have now solved the mystery. When I looked at the timing and shape of the rise and fall, a memory was triggered of college student life.

0909_TheatreL_005a — From strangethoughtsbyjohn.blogspot.com. Click to go to the link.

I have no way of knowing if this is true, but let’s assume that on Monday the 21st, over 300 students attended the first of the week’s Monday, Wednesday, Friday classes on introductory science in a large University. The lecture hall was packed when the professor announced that a paper on Personal Black Holes was due on Monday week.

On that day (Monday) ten students hit Google and immediately found my blog posting on Personal Black Holes. The next day 25 students hit the site followed on Wednesday (perhaps encouraged by a reminder in class) and Thursday by a much larger group of students. On Friday, 35 procrastinators did the same thing.

I don’t think I would be wrong to suggest that after a Friday night spent in college recreation, Saturday was a day of hangovers and recovery. (Yes, I am speaking from personal experience.) No one hit my site on Saturday, and I imagine the majority were resting, or perhaps writing.

On Sunday, it appears that three late-bloomers hit the site, and the rest were preparing their paper for Monday.

Early Monday morning, one desperate procrastinator hit the site. I can just imagine the student screaming, “You have got to be kidding! This is a joke?”

Yes, it was a joke, a fact the average student figured out in 39 seconds before moving on.

Government and industry is constantly pressing for metrics, ways to measure business success other than from sales. The problem with metrics is that figuring out what to do with the numbers is not always obvious . What do they represent?

Since my site is not a business, and does not earn me a cent, I normally pay no attention to its metrics. However, this time, after moving beyond my initial alarm, I felt that I might be gaining insight into the hidden “research” trends of young college students. As a scientist, that intrigues me.

It would be more intriguing if someone discovered that A students were the first to turn to Google for answers. I’m sure Google would find that satisfying.

It could of course be just the opposite. Perhaps top students hit the library first and then follow up with Google search as a last check. Actually, that result would surprise me, but arguably it cannot be ruled out.

Lastly, it could be that my college class hypothesis is completely wrong. It could be that Chechen rebels were exploring ways to solve their political/military problem, but somehow I doubt it.

As we scientists are trained to say, more research is needed.

GoPro, YouTube, and the Need for Speed

Have you ever watched a local sailboat race from the shore?

It’s not exactly an adrenaline-pumping spectator sport. On the boats of course there is plenty of excitement — shouting, sometimes cursing. But from shore, all the on-boat drama is missing.

GoPro cameras have ushered in a new era of taking the viewer into the action. And based on the action that I commonly see on the Internet, that action is not of local sailboat races. It is instead full of speed and thrills. The penultimate example of testosterone-driven thrill-seeking, in my opinion, is the dangerous sport of wingsuit flying, always perilously close to terrain.

The visual rush is not subtle. You are left with the impression that any second you’ll witness a fatal crash. You leave the video thinking that the flyer is one very brave, very skilled, and very lucky person. Or else you just think they’re CRAZY!

But honestly, I’d love to be that crazy— just once anyway.

When I watch such videos on YouTube I get the sense that I am a spectator at a blood sport event. There is beauty and grace which I admire, but ultimately I know there is a risk to the participant, as evidenced occasionally by the literally rib-splitting, pink mist endings to some of those flights. We enter into the action, but comfortably in front of our TV or computer screens with no personal risk to ourselves.

Arguably we are really not so different from the crowds at the Gladiator games, or for a more modern though fictional example, the Hunger Games.

What I like about the new class of miniature, high-definition video cameras is that they allow us to video what we love doing and then share it with the world. That’s nice, but unless what you do is high speed, endearingly cute, or down-right funny, it may be difficult to attract viewers.

I’ve uploaded flying videos, including the high-definition video below, but they are not exciting. Instead, they appeal, I think, to those who simply love flight: the visual sensations of landing, of entering clouds or skimming cloud tops. That type of flight is the way the FAA expects pilots to fly — safely. Yet safe flight is also capable of generating visual sensations that secretly thrill even highly experienced pilots, and keep them in love with their profession.

On the other hand, the adrenalin-packed videos that high-definition cameras provide can entice some pilots to fly unsafely, simply to titillate the cameraman and the viewer. I suspect the pilot in the following video got a high viewer count but I also suspect his wings are about to be clipped by the FAA.

I am very unlikely to engage in risky flying simply because it looks thrilling when posted on the Internet. I want to keep my license; it is a treasured privilege to be able to fly. But also because I’ve lived long enough to know it is quite a different thing to watch a Miss Universe pageant, and quite another to entertain a pageant contestant when she shows up unexpectedly at your door. The thrill may be more intense in the latter case, but the personal risk may be far greater; especially if your significant other meets her at the door.

Sailboat race photo by Lewis Westwood Flood on Unsplash

My Respiratory System is So Embarrassed

stk85284cor — Royalty free image from Punchstock.com

“Respiratory embarrassment” is an uncommon phrase most likely spoken by physicians and physiologists.

This week I found myself telling an engineer that “respiratory embarrassment can lead to an untoward event”. It quickly became apparent from the puzzled stare I received that I was not communicating.

Scientists and some medical personnel tend to do that; fail to communicate. In fact, they do it a lot.

What I was really saying is that in the right circumstances a person could have difficulty breathing, and that difficulty could cause something bad to happen; an “untoward” event. That bad thing would not necessarily be an aircraft crash, or in the case of a diver, a drowning, but it would mean that the pilot’s or diver’s performance would be impaired.

Why didn’t I just say so?

Laziness I suppose. I was using the language clinicians and physiologists are taught in graduate or medical school, and it flows out of our mouths naturally, without effort. Translating those same words into laymen’s terms takes time and effort.

I next started talking about respiratory impedance, a term understood by some but not all engineers, and rarely if ever by laymen. So once again I was not communicating well with all of my audience which was composed mostly of engineers, but not entirely.

That was the case until I used pictures to explain the otherwise difficult concepts of respiratory impedance and physiological embarrassment. The images below seemed to work, so I thought it worthwhile to share those images with you.

For you engineers, respiratory impedance is proportional to the sum of respiratory flow resistance and pulmonary and chest wall elastance.

pb-110104-buried-shulman_photoblog900 — From Shulman photoblog.

So what is that?

Well, for elastance, at least chest wall elastance, think of being buried to your neck in sand. Breathing difficulty comes from the difficulty of moving your chest wall in and out with the weight of sand pressing in on all sides. The pressure of sand impedes your breathing, hence elasticity (the inverse of compliance) is a major component of respiratory impedance.

Based on the photo of the young man pictured on the right, being partly buried for supposedly therapeutic reasons is not a pleasant experience.

Some might disagree. The man on the left is an actor in the 2008 French short film Le Tonneau des Danaïdes by David Guiraud, who seems quite at ease impeding his breathing for the sake of art. I’m guessing he’s either very dedicated, or very well paid.

In diving, respiratory elastance can be elevated by tight fitting wet suits; in aviators by tight fitting chest pressure garments, and in patients, by pulmonary fibrosis brought about by, for example, asbestos exposure.

Another key component of respiratory impedance, that thing that causes respiratory embarrassment, is flow resistance. Sticking your head in the sand would certainly be one way of generating

head-in-sand — *This image is found randomly throughout the web without attribution. The original source is unknown.*

severe respiratory resistance, with its attendant embarrassment.

out-of-breath-286x300 — From news.menshealth.com

Clinically, there are far more common sources of respiratory resistance, for example the narrowing of air passages in the lung caused by asthma. (Sticking your head in sand is probably a reasonable analogy to the sensations experienced during an asthma attack.) Chronic obstructive pulmonary disease (COPD) can also lead to a significant increase in respiratory resistance.

When you focus on the human respiratory system, the body parts shown in pink below, keep in mind that breathing can be impaired by things occurring inside the body (like asthma, COPD, fibrosis) or outside the body. Any life support system used for aviation, diving, mining, or firefighting imposes an impedance on breathing. That impedance in turn can lead to breathing difficulty, which can result in a failure to complete assigned duties.

Perhaps that’s where the “embarrassment” part comes in.