Science and Technology | John Clarke Online

Siri versus Napoleon Bonaparte

Napoleon Bonaparte once famously said, “A soldier will fight long and hard for a bit of colored ribbon.”

At precisely 10:09 this morning I was in an office discussing awards, and the lack thereof, for civilian service members in military organizations. It was a matter of fact discussion, contrasting the award system for civilians and the military. And at that moment, Napoleon’s famous quote came to mind. I reminded that executive of the above quote.

My fellow workers and I talk frequently, and there have been numerous discussions in that office, and elsewhere, that have been of a sensitive nature.

As I turned and returned to my office, I heard a familiar voice coming from my pocket. “That’s not nice!” it said.

In utter dismay, I pulled my iPhone from my pocket where it had lain untouched and unused for quite some time. And that was when I saw the following plainly written on my phone’s screen.

Siri was scolding me!

Unknown to us, Siri had been listening, transcribing what it THOUGHT I was saying, clearly imagining vulgarity where there was none. After I ended the conversation, Siri addressed me like she was my mother.

Now, a human would know those transcribed words were ludicrous, nothing but gibberish, but not the phone’s AI system controlling Siri. Unbelievably, that system took the gibberish seriously, perhaps by parsing a few words out of context. And in spite of that stupidity, Siri felt led to judge me!

Perhaps smart phone AIs are taking themselves too seriously. Perhaps they think they have advanced enough that they now think they can pass judgment on human speech.

A few years ago, in another meeting, in another room, Siri spoke up unbidden while we were discussing sensitive project planning.

The door to the conference room had been closed so we wouldn’t be disturbed. But disturbed we were when Siri suddenly spoke and said, “I don’t know what you mean.”

Everyone at the table stared first at my phone and then at me, perhaps wondering if I’d been recording the planning meeting.

AI is certainly becoming increasingly intrusive. But as shown by Siri’s text message to me today, it’s still not smart. And arguably that’s a scary thing.

For example, supposedly China is using data collected from social apps (collected by various AI systems) to rate the trustworthiness of its citizens. That’s bad enough, but what if the data collected is garbage like the recorded text today, and the AI uses that faulty data to make a perfunctory and wildly incorrect judgment?

And, scary thought, what if that social monitoring trend were to spread to the U.S., and your character could to be judged based on the digital algorithms of certifiable AI idiots?

If that doesn’t worry you, perhaps it should. It certainly did me, enough to cause me to shut down all access to Siri … for almost 24 hours, until I was driving home and said, “Siri, call home.”

She was silent, sullen, unresponsive.

Dead Space – A Lesson in Survival

Dead Space is a defunct, or shall we simply say “dead,” survival horror game that enthralled computer game players from 2008 to at least 2013. Sadly, the company that designed the horrifically beautiful game, Visceral Games, is no more. It has been, so to speak, eviscerated.

The main protagonist of the Dead Space Series was Isaac Clarke. If I was a game player I think I would be an Isaac fan since he was one of those rare Clarke’s known as a “corpse-slaying badass.” If in some unforeseen future my survival depended on being such a slayer, I’d want to be badass about it too, just like Isaac. As they say, anything worth doing …

Isaac Clarke and his Dead Space world make a great segue to introduce another matter of personal survival. And that is DEAD SPACE in underwater breathing equipment.

Clarke has proven to be equally at home underwater and in space due to his interesting cyan-lighted helmet. (I’m not sure where his eyes are, but perhaps in the 26th century a multi-frequency sensor suite makes a simple pair of eyes redundant.)

Historically, the U.S Navy used the venerable MK 5 diving helmet and the MK 12 diving helmet, which although they had no sensor suites, at least allowed divers to work at fairly great depths without drowning. However, they shared a common problem: Dead Space.

In ventilation terms, dead space is a gas volume that impedes the transfer of carbon dioxide (CO2) from a diver or snorkeler’s breath. When we exhale through any breathing device, hose, tube, or one-way valve we expect that exhaled breath to be removed completely, not hanging around to be re-inhaled with the next breath.

But a diving helmet inevitably has a large dead space. The only way to flush out the exhaled CO2 is by flowing a great deal of fresh gas through that helmet. A flow of up to six cubic feet of gas per minute is sometimes needed to mix and remove the diver’s exhaled breath from a diving helmet like the MK 12.

In more modern helmets, the dead space has been reduced by having the diver wear an oral-nasal mask inside the diving helmet, and giving the diver gas only on inhalation using a demand regulator like that used in scuba diving. The famous series of Kirby Morgan helmets, arguably the most popular in the world, is an example of such modern helmets.

Full face masks are used when light weight and agility is required, as in public service diving, cold water diving, or in Special Forces operations. The design of full face masks (FFM) has evolved through the years to favor small dead space, for all the reasons explained above.

Erich C. Frandrup’s 2003 Master’s Thesis for Duke’s Department of Mechanical Engineering and Materials Science reported on research on a simple breathing apparatus, snorkels. You can’t get much simpler than that.

Frandrup confirmed quantitatively what many of us knew qualitatively. Snorkels are by design low breathing resistance, and low dead space devices. Happily, the dead space can be easily calculated, as simply the volume contained within the snorkel.

Surprisingly, some snorkel manufacturers have recently sought to improve upon a great thing by modifying snorkels, combining them with a full face mask. The Navy has not studied those modified snorkels since Navy divers don’t use snorkels. However, you don’t get something for nothing. If you add a full face mask to a snorkel, dead space has to increase, even when using an oral-nasal mask.

So what?

In 1995 Dan Warkander and Claus Lundgren compared the dead space of common diving equipment, including full face masks, and reported on increases both in diver ventilation and the maximum amount of CO2 in the diver’s lungs. Basically the physiological effects of dead space goes like this: we naturally produce CO2 during the process of “burning” fuel, just like a car engine does. (Of course our fuel is glucose, not gasoline.) The more we work, the more CO2 we produce in our blood, and the more we have to breathe (ventilate) to expel that CO2 out of our bodies.

If we are exhaling into a dead space, some of that exhaled CO2 will be inhaled into our lungs during our next breath. That’s not good, because now we have to breathe harder to expel both the produced CO2 and the reinhaled CO2. In other words, dead space makes us breathe harder.

Now, if we’re breathing through an underwater breathing apparatus, hard breathing is, well, hard. As a result, we tend to get a little lazy and allow CO2 to build up in the blood stream. And if that CO2 get high enough, it’s lights out for us. Underwater, the lights are likely to stay out.

In a computer game like Dead Space, no one worries about helmet dead space. But if a movie is ever based on the game, whichever actor plays Isaac Clarke should be very concerned about the most insidious type of Dead Space, that in his futuristic helmet. It can be (need I say it?) — deadly.

If I Had Written the Score to Interstellar

If I was Hans Zimmer, I would be a bit annoyed.

What is arguably the best score Hans Zimmer has ever written, the music for Interstellar, has thrilled me to my core. However, I came to that conclusion by an indirect route.

Like many of you, I saw the movie in all it’s cinematic glory when it was released in 2014. But it was not until 2017 that I fell in love with it, both the movie and the score.

In preparation for an after-dinner talk to a panel of the American Heart Association’s 2017 Science Conference, I was looking for an inspirational way, preferably with great video and sound, to describe the sport of competitive free diving. This past summer I had the opportunity to meet some of the world’s best free divers and free diving instructors in a Colloquium put together by the University of California at San Diego, Center of Excellence in Scientific Diving.

I had pretty much given up on finding something to help me illustrate the beauty, and challenges, of competitive free diving. That changed, however, when I came across a posting from a group of tactical military divers. In a short 3-minute video the young French diver Arnaud Jerald set his personal free diving (CWT, Constant Weight Dive discipline) record of 92 meters in a competition in Turkey. He placed third in a field which included world record holders in the same event.

Three things made the diving video great, in my opinion: 1) the subject matter which vividly shows a human activity little known by most people, and understood by even fewer; 2) steady and clear video produced by a new underwater camera, the Diveye, and 3) the accompanying music.

A film score is only successful if it aids the audience in generating an emotional response to a movie scene. In that respect, a great movie hinges not only on good acting and script, but on an almost telepathic connection between the film director/producer and music director/composer.

In the free diving video clip, the accompanying music swelled in concert with the audience’s tension, generated perhaps unconsciously in response to the drama of the moment. And then there was organ music at just the right point. For me a pipe organ truly is the most impressive and grand of any musical instrument.

And just when the cinematic moment was right, you could hear the heart beats, helping us realize what a strain it must have been on young Jerald’s heart as he reached his deepest depth, far from the surface, and air.

Indeed, when I gave the presentation, the video clip seemed to have the effect on the audience that I was looking for. But afterwards, I was relieved that no one had asked me where that music came from. I had no idea.

I don’t recall what led me to Interstellar as the music source: it may have been a random playing of movie soundtracks on a music streaming service, but once I heard a snippet, I recognized it. “That’s it!” I shouted to no one in particular.

It wasn’t just me; my family, including a nine-year old granddaughter had heard me rehearse my talk many times, and they also immediately recognized the similarity between the free diving video, and part of the Interstellar soundtrack.

The closest musical correlation to the diving video was the “Mountains” track in the movie soundtrack. Strangely, the match was not perfect. In fact the differences were easily notable, a fact I discovered after I bought both the movie and the Hans Zimmer soundtrack. And I must note, I think the music in the diving video is better.

Perhaps the full music was present in the original version of the movie, and perhaps some fancy mixing in the sound room deleted it. If so, too bad. But I must admit, the quiet musical nuances would have been missed during the cacophonous sound of a 4000 foot tall tidal wave sweeping upon a tiny spacecraft. There was lots of shouting and screaming.

As for my opinion that Hans Zimmer might be annoyed, well, I suggest you watch the portion of the full movie where the Mountain track rises to prominence. That is the part where the tidal wave, initially mistaken as mountains, appears on the horizon of the first planet the Horizon space craft landed on outside of our galaxy.

As exciting as the action was, and as wonderfully crafted the dialog and acting, it obscured the finer points of the music. Fortunately, the free diving video, coming as it does with no dialog at all, puts the music in the perspective that I, at least, can completely enjoy.

I find it fitting that in both videos, the incredibly powerful music was used to showcase humans extending themselves to their absolute limits. Of course, one of those stories is fictional, and the other is real.

A Matter of Chance: Music Makes the Video

I was recently asked to give a 30-minute after-dinner talk to the 3CPR Resuscitation Panel of the American Heart Association at their annual scientific meeting in Anaheim, CA. In the audience were scientists, cardiologists, anesthesiologists, anesthetists, emergency physicians, and resuscitation technicians. It was a multimedia event with professionally managed sound and video.

Knowing that the group would be well acquainted with the role of chance in medical procedures, I chose to use a segue from medicine into the topic of extreme adventures in military and civilian diving. The focus of the talk was on how chance can turn adventures into mis-adventures.

I revealed three areas where Navy Biomedical Research is expanding the boundaries of the state of the art in military and civilian diving. One area was in deep saturation diving, another was polar ice diving, and the third was breath hold diving.

As an introduction to polar diving, I wanted to create a video travelogue of my National Science Foundation-sponsored research and teaching trips to the Arctic (Svalbard) and Antarctica (McMurdo Station and vicinity.) These projects were spearheaded by the Smithsonian Institution, and my participation was funded in part by the U.S. Navy.

To begin the preparation of the video, I assembled my most relevant photos, and those taken by various team mates, and imported them into my favorite video editing software, which happens to be Cyberlink Director.

Then I went looking for potential sound tracks for the approximately 5 minute video. Considering the topic, I thought Disney’s Frozen would have familiar themes that might be acceptable. I rejected a number of YouTube videos of music from Frozen; most were too close to the original and included vocal tracks. Finally I came across the “Let It Go Orchestral Suite” composed by the “Twin Composers,” Andrew and Jared DePolo.

It was perfect for my application. I extracted the audio track from the Suite as shown on YouTube, imported it into Director, and lined it up with the nascent video track which included all images and other video segments.

To match the music to the video, I simply cut back on the duration for each of 97 images, keeping the other 5 videos in their native length. By experimentation, I found that 3.21 seconds per image resulted in the last image fading out as the music came to a close and the end credits began to roll.

On the first run through of the new video, I couldn’t find anything to complain about; which for me is rare. So I ran it again and again, eventually creating an mp4 file which would play on a large screen and home audio system. But I couldn’t help notice that the gorgeous score would sweeten at interesting times, and serendipitously change its musical theme just as the video subject matter was changing.

How fortunate, I thought. It was then that I began to realize that “chance” had worked its way into the production effort, in an unexpected way.

First, the music seemed to my ear to be written in 4/4 time, with each measure lasting 3.2 seconds, precisely, and purely by happenstance matching the image change rate. At a resulting 0.8 seconds per beat, or 75 beats per minute, that placed the sensed tempo in the adagietto range, which seemed appropriate for the theme of the music. (Without seeing the score, I’m just guessing about the tempo and timing. But that’s how it felt to me.)

The timing coincidence was rather subtle at first, but as the finale began building at the 3:39 minute mark, the force of the down beat for each measure became more notable, and the coincidence with image changes became more remarkable. There was absolutely nothing I could do to improve it.

In some cases the technical dissection of music can be a distraction from the beauty of the music, but I’ve done it here merely to point out that sometimes you just luck out. In this case it truly was a matter of chance.

In my mind, the DePolo Orchestral Suite makes the video. Hope you enjoy the show.

To learn more about these composers and their music, follow this link.

Cereal Was Almost the Death of Me

This year, 2017, marks the 120th year that Grape Nuts cereal has been in existence. Generations have been raised on it, and as the 1921 ad would suggest, it seems to help little bodies grow big and strong. As the Post company says, “There’s a Reason” for the cereal’s success.

However, through some weird quirk, some random juxtaposition of breath and nerves, a single, tiny particle of this delicious blend of barley and wheat almost killed me.

Or so it seemed at the time.

I consider Grape Nuts part of a paleo diet, of sorts. As cereals go, it’s primitive. It is merely ground bits of grain that never needed to be squeezed into flakes, or coated with sugar or artificial flavorings. For me, it’s like getting back to the basics of breakfast, or in this particular case, an evening snack.

On the night of my close call, while my wife was watching TV, I settled into my home office to edit my newest book while I snacked on a demi-bowl of Grape Nuts, wet with skim milk.

No doubt your parents lectured you repeatedly about the dangers of talking with food in your mouth. Well, in adherence to my parent’s scolding, I was not talking when it happened. I was quietly reading, and breathing.

And then, in an instant, I could not breathe, at all. I could not speak or yell out. I could not swear, or call for help. No air could enter or leave my lungs.

As I looked to the doorway, terrified, half hoping for my guardian angel to appear and magically save me, I realized that if I didn’t do something, quick, I would die. I was most unexpectedly suffocating.

I stood up, planning to head to the bathroom out of some strange thought that it might be my salvation, or at least an easier place to clean up the vomitus mess or whatever else follows death by asphyxiation. And as I reached the door frame a scant twelve feet away from where I’d been sitting, I could feel myself becoming faint.

This could not be happening. What an inglorious way to die.

With all the fortitude I could muster, I was determined to make it into the bathroom before I passed out. A second later, I was bent over a sink, supporting my upper body with my hands, trying with all my might to pull air into my lungs.

Finally, I found that with almost superhuman effort I could squeeze a little air through whatever was blocking its flow. The result was a high pitched nonhuman sounding squeal, a falsetto screech higher than even a little girl can produce. Physicians call it stridor, which sounds like this.

But at least it was something. Again and again I managed to suck in just enough air to keep me alive, one loud screech after another.

In the meanwhile, my greatly concerned wife was asking, “Are you OK, are you OK?”

No, I was not at all OK, but I could not communicate that fact, other than to make that hellish shriek. But with each shriek a few more oxygen molecules entered my oxygen-starved lungs.

And as the fog of impending collapse slowly began to clear, I was finally able to cough.

After that cough, there lay in the sink a tiny granule of cereal, presumably the little spec that landed in a sensitive spot in my larynx or “voice box”, triggering the spasm which tightly closed my vocal cords. With the cords, or more properly “vocal folds”, closed, air cannot enter the lungs.

Under normal conditions, a person can hold their breath for two to three minutes without losing consciousness. But as I later analyzed what had happened, I realized that the particle of cereal was most likely sucked into my airway when I was just beginning to inhale, at the bottom of my “tidal volume.” So my lungs were not full of air.

Logically, when involuntarily holding your breath with lungs only partially inflated, the 2-3 minute rule may not apply. So, there was a chance that I was about to lose consciousness from hypoxia.

As I later discovered, laryngeal spasm is short-lived, and resolves within a few minutes, leaving the terrified victim shocked but relieved to be able to breathe again.

The aftermath of this incident was that I now realize how little we appreciate the simple act of breathing. For our entire lives we never think about it. It just happens.

Until it doesn’t.

I still enjoy my Grape Nuts, and highly recommend it to anyone looking for the simple pleasures of life. But at the same time, I’m now a little more careful when I’m eating, especially if my attention is directed towards something else. Multitasking while eating can be scary.

Living Off Universal Energy. Really?

I thought I was misreading the title of the news article. I adjusted my glasses, then looked again.

Sure enough, the news headlines this past week actually reported on a young couple, reportedly a Breatharian couple, who claimed they had no need for food. They lived off of Universal energy, whatever that is. Most amazingly, the news-hungry press actually reported the story, obviously without a bit of fact checking.

As a physiologist, I know that is a patently ridiculous claim. It is impossible for humans to survive without eating. And as a science fiction author, I know it is not even good science fiction. The best science fiction maintains at least a little scientific accuracy.

Could it be fantasy? Maybe, but the story was reported as being true, with no hint of tongue-in-cheek.

However, it did remind me of a revelation of sorts from a few months ago, coming to me in a split second after a quick glance to the side of the road. What attracted my attention as I passed by at 55 miles per hour was a gorgeous white egret, like the one pictured, foraging for frogs and tadpoles in a ditch recently filled to overflowing with water from several days of downpours.

By stuart Burns from Erith, England (_MG_7185 Uploaded by snowmanradio), via Wikimedia Commons

And then it struck me: wouldn’t it be nice if animals did not have to die just so that other animals can live?

Now that’s a fantasy for you. Of course life is predicated upon death. Big animals eat smaller and weaker animals. Physicality cannot exist without death; you cannot live in the body unless something else dies. That’s life, pure and simple. It sucks to be the little guy.

But what about after life? Well, at the risk of turning in my scientific credentials, I will admit I do believe in an after-life, Heaven if you will, for reasons which I will not go into here. But it struck me in that brief moment of observing a beautiful bird, that only in a spiritual realm could energy exist without the simultaneous extinguishment of life.

To my way of thinking, that may be the single greatest distinction between the spiritual realm and the physical realm.

So thank you Breatharian couple, practitioners of Inedia, for helping me remember my roadside revelation. Perhaps there is a place in some alien realm where beautiful birds, and beautiful frogs, and even humans can coexist without one eating the other. Maybe there is some parallel universe where our laws of physics don’t apply.

Perhaps we will someday discover that parallel universe, and call it — Heaven.

DNA: A Matter of Trust

In combat, we trust our buddies with our lives. We have their back and they have ours. When submitting to surgery, we trust the medical team with our lives, and usually that trust is not betrayed. But should we be willing to trust strangers with our very essence, our DNA?

Recently I was trying to solve a plot problem in the science fiction thriller, Triangle. The storyline relied on a particular individual being singled out by the government for monitoring, not for what he had done, but for who he was.

After finishing the novel, I went back to tie up loose ends in the plot. One such loose end involved a question: How could the government know that this one person out of millions had an unrecognized super power? He was a main character in the book and so I could not ignore that question. Certainly it helps the reader suspend disbelief if the plot elements are plausible, at least superficially.

I did not have to puzzle over that question very long before an advertisement for Ancestry DNA popped up on my computer screen.

That was it!

And so the following text flowed quickly.

The characters in this conversation are Sally Simpkin (AKA Pippi Longstocking) and Joshua Nilsson, identified below by their initials. She was trying to explain to Nilsson why she and her employers had been monitoring him.

SS: “[The government] detected that you had a high probability of having certain prescient capabilities.”
JN: “Forgive me for being a bit skeptical. Why can’t you tell me [how]?”
SS: “I’m not even cleared to know the process. I just took the assignment. It had something to do with a DNA sample you submitted.”
JN: “DNA? The only DNA I’ve submitted was for genealogy research.”

Triangle was published on May 21, 2017. On May 25, the following BBC headline appeared in my browser.

Ancestry.com denies exploiting users’ DNA. “A leading genealogy service, Ancestry.com, has denied exploiting users’ DNA following criticism of its terms and conditions.”

So, is this author also prescient like Nilsson? Or is this blogger merely a bit jaded.

Genealogy services have a difficult time competing in the world market. After all, there are only so many retired folks trying to trace their family history and solidify their genetic place in the world before their demise. Speaking for myself, I started my genealogy research years ago, picking it up from my grandmothers who told tales of Civil War Colonels and Carpet Bagger treachery, and murder. In fact, I’ve posted on this blog before about some of my discoveries.

With the advent of computers and the availability of free records from the Mormon Church, the ease of doing genealogical research exploded. Some of the software and services were either free or inexpensive. Of course, “free” doesn’t do much for a service provider’s cash flow. So, into each CEO’s mind comes, sooner or later, thoughts of monetization. How could Facebook’s Zuckerberg and others turn a free service into something that can make them gazillions? In the case of genealogy services, they started by charging a monthly access fee, and in one case, by enticing viewers to keep paying fees by waving images of fig leaves to attract their attention. That was a strange but brilliant ploy that worked very well on this researcher.

The next step in monetization is now universal: sell ads to companies who want access to the growing body of amateur genealogists. The final ploy, and by far the most ethically troubling, is selling information about users of computer services. First there were those pesky cookies, but now there is blood, or saliva more exactly.

For some companies, it is not enough to know what users search for. There is now a market for information about who you are, your very genetic essence, which is hidden even to you. But some companies like 23andme, Ancestry, MyHeritage, GPS Origins, Living DNA, and Family Tree DNA, let you take a peek into your genes, for a price.

The ironic thing is, this most personal information is not only freely given, but people actually pay the DNA harvesters to harvest their most sacred self. And of course, once that has been done, your genetic-identity can be sold (read the fine pint). While we are urged to protect ourselves from identity theft, isn’t it odd that we are at the same time being enticed into giving away our most precious identity of all, our DNA? And we seem to be doing so gladly, blithely unaware of the implications for us and our progeny.

But don’t let the natural skeptic in me show through too strongly. I do, after all, have faith that everything we’re being asked to store in the “cloud” is actually as secure as cloud storage facilities (whatever those are) claim. And I’m sure the secrets buried deep in our genes are forever kept private, and safe from hackers.

But then, there is that troubling Orwellian Consent Form.

Oh well, Sally Simpkin’s monitoring assignment in Triangle is purely fictional. Surely, no government would really have an interest in our genes.

Or would it?

U.S. Navy Diving and Aviation Safety

Blood pressure is not the only silent medical killer. Hypoxia is also, and unlike chronically elevated blood pressure, it cripples within minutes, or seconds.

Hypoxia, a condition defined by lower than normal inspired oxygen levels, has killed divers during rebreather malfunctions, and it has killed pilots and passengers, as in the 1999 case of loss of cabin pressure in a Lear Jet that killed professional golfer Payne Stewart and his entourage and aircrew. Based on Air Traffic Control transcripts, that fatal decompression occurred somewhere between an altitude of 23,000 feet and 36,500 ft.

In most aircraft hypoxia incidents, onset is rapid, and no publically releasable record is left behind. The following recording is an exception, an audio recording of an hypoxia emergency during a Kalitta Air cargo flight.

Due to the seriousness of hypoxia in flight, military aircrew have to take recurrent hypoxia recognition training, often in a hypobaric (low pressure) chamber.

As the following video shows, hypoxia has the potential for quickly disabling you in the case of an airliner cabin depressurization.

Aircrew who must repeatedly take hypoxia recognition training are aware that such training comes with some element of risk. Rapid exposure to high altitude can produce painful and potentially dangerous decompression sickness (DCS) due to the formation of bubbles within the body’s blood vessels.

In a seminal Navy Experimental Diving Unit (NEDU) report published in 1991, LCDR Bruce Slobodnik, LCDR Marie Wallick and LCDR Jim Chimiak, M.D. noted that the incidence of decompression sickness in altitude chamber runs from 1986 through 1989 was 0.16%, including both aviation physiology trainees and medical attendants at the Naval Aerospace Medical Institute. Navy-wide the DCS incidence “for all students participating in aviation physiology training for 1988 was 0.15%”. If you were one of the 1 and a half students out of a thousand being treated for painful decompression sickness, you would treasure a way to receive the same hypoxia recognition training without risk of DCS.

With that in mind, and being aware of some preliminary studies (1-3), NEDU researchers performed a double blind study on twelve naïve subjects. A double-blind experimental design, where neither subject nor investigator knows which gas mixture is being provided for the test, is important in medical research to minimize investigator and subject bias. Slobodnik was a designated Naval Aerospace Physiologist, Wallick was a Navy Research Psychologist, and Chimiak was a Research Medical Officer. (Chimiak is currently the Medical Director at Divers Alert Network.)

Three hypoxic gas mixtures were tested (6.2% O2, 7.0% and 7.85% O2) for a planned total of 36 exposures. (Only 35 were completed due to non-test related problems in one subject.) Not surprisingly, average subject performance in a muscle-eye coordination test (two-dimensional compensatory tracking test) declined at the lower oxygen concentrations. [At the time of the testing (1990), the tracking test was a candidate for the Unified Triservice Cognitive Performance Assessment Battery (UTC-PAB)].

As a result of this 1990-1991 testing (4), NEDU proved a way of repeatedly inducing hypoxia without a vacuum chamber, and without the risk of DCS.

The Navy Aerospace Medical Research Laboratory built on that foundational research to build a device that safely produces hypoxia recognition training for aircrew. That device, a Reduced Oxygen Breathing Device is shown in this Navy photo.

070216-N-6247M-009 Whidbey Island, Wash. (Feb 16, 2007) Ð Lt. Cmdr. James McAllister, from San Diego, Calif. sits in the simulator during a test flight using the new Reduced Oxygen Breathing Device (ROBD). The ROBD is a portable device that delivers a mixture of air, nitrogen and oxygen to aircrew, simulating any desired altitude. Combined with a flight simulator the ultimate effect replicates an altitude induced hypoxia event. McAllister is the Director of the Aviation Survival Training Center at Whidbey Island. U.S. Navy photo by Mass Communication Specialist 1st Class Bruce McVicar (RELEASED) — Whidbey Island, Wash. (Feb 16, 2007) Lt. Cmdr. James McAllister, from San Diego, Calif. sits in the simulator during a test flight using the Reduced Oxygen Breathing Device (ROBD). The ROBD is a portable device that delivers a mixture of air, nitrogen and oxygen to aircrew, simulating any desired altitude. Combined with a flight simulator the ultimate effect replicates an altitude induced hypoxia event. McAllister is the Director of the Aviation Survival Training Center at Whidbey Island. U.S. Navy photo by Mass Communication Specialist 1st Class Bruce McVicar.

Although NEDU is best known for its pioneering work in deep sea and combat diving, it continues to provide support for the Air Force, Army and Marines in both altitude studies of life-saving equipment, and aircrew life support systems. Remarkably, the deepest diving complex in the world, certified for human occupancy, also has one of the highest altitude capabilities. It was certified to an altitude of 150,000 feet, and gets tested on occasion to altitudes near 100,000 feet. At 100,000 feet, there is only 1% of the oxygen available at sea level. Exposure to that altitude without a pressure suit and helmet would lead to almost instantaneous unconsciousness.

OSF FL 900 — A test run to over 90,000 feet simulated altitude.

Herron DM. Hypobaric training of flight personnel without compromising quality of life. AGARD Conference Proceedings No. 396, p. 47-1-47-7.
Collins WE, Mertens HW. Age, alcohol, and simulated altitude: effects on performance and Breathalyzer scores. Aviat. Space Environ Med, 1988; 59:1026-33.
Baumgardner FW, Ernsting J, Holden R, Storm WF. Responses to hypoxia imposed by two methods. Preprints of the 1980 Annual Scientific Meeting of the Aerospace Medical Association, Anaheim, CA, p: 123.
Slobodnik B, Wallick MT, Chimiak, JM. Effectiveness of oxygen-nitrogen gas mixtures in inducing hypoxia at 1 ATA. Navy Experimental Diving Unit Technical Report 04-91, June 1981.

A Geometric Mind

211px-Gestalt_in_the_Eye — By Impronta – Own work, CC BY-SA 3.0, https://commons.wikimedia.org

I challenge you to describe the following images in terms of simple geometric shapes: shapes such as rectangles and circles, and flat surfaces called planes.

If you see one of those shapes in the image, then mentally note it.

You may not be able to completely define the image with those simple shapes, but at least note those parts of the image where you can see a plane, or a rectangle, or a circle.

The shapes are not likely to be seen dead on; they may be seen at an oblique angle.

Color is an interesting variable in the images, but it is not the primary focus of this exercise. The ability to use geometrical shapes is the point of this post.

The first such shape is Figure 1.

Temps0600-3blank1 — Copyright John R. Clarke.

The next shape is Figure 2. Do you see a lighted plane on the left partially obscured by an extruded rectangle, otherwise known as a rectangular prism or cuboid?

Figure 3. Yet another image, somewhat similar to Figure 2:

And a fourth image, Figure 4.

Temps2000-2blank1 — Copyright John R. Clarke.

Now, lets try some variations on the theme.

The four images immediately above are identical to the first four images, but by seeing them in this order you may detect that there are only two unique images.

The images on the right are simply the images on the left rotated 180°; that is, they are turned upside down.

And yet most people identify an entirely different geometry, depending on which way the images are rotated.

So, seeing is believing …

… or is it?

I do not know if this visual phenomenon has a name or not: I accidentally discovered it when looking at images to post on a laboratory wall. One figure looked unfamiliar; I was confused by it, until I happened to rotate it.

As the French say, voila. It was an optical illusion caused by our brain’s tendency to look for familiar shapes in unfamiliar and potentially confusing images.

There is a literature on the illusions of inverted images where images have been digitally manipulated (sometimes called the Thatcher Effect), but the images above have not been altered in any way.

How Will You Try to Kill Me?

Émile_Jean-Horace_Vernet_-_The_Angel_of_Death — Émile Jean-Horace Vernet-The Angel of Death

It’s been over three years since I posted a cautionary tale about oxygen sensors in rebreathers, and the calamities they can cause. Since then, the toll of divers lured to their death has been steadily mounting. In one week alone in April 2016, at almost the same geographical latitude in Northern Florida, there were two diving fatalities involving rebreathers. It is an alarming and continuing trend.

I know a highly experienced diver who starts each dive by looking at his diving equipment, his underwater life support system, and asking it that title question: How will you try to kill me today?

This deep cave diver, equally at home with open circuit scuba and electronic rebreathers, is not a bold cave diver. He is exceptionally cautious, because he is also the U.S. Navy’s diving accident investigator. He has promised me that his diving equipment will never end up in our accident equipment cage.

He and I have seen far too many of the diving follies where underwater life support systems fail their divers. But the crucible in which those fatal failures are often born are errors of commission or omission by the deceased.

Carelessness and an attitude of “it can’t happen to me” seem all too prevalent, even among the best trained divers. Divers are human, and humans make mistakes. Statistically, those accidents happen across all lines of experience: from novice divers, to experienced professional and governmental divers, and even military divers. They all make mistakes that can, and often do, prove fatal.

It is exceedingly rare that a life support system fails all by itself, since by design they are robust, and have either simple, fool-proof designs, or redundancy. In theory a single failure should not bring a diver to his end.

http://www.jj-ccr.com/the-jj-ccr/rebreather-lid.aspx — The “head”, triplicate oxygen sensors, oxygen solenoid and wiring leading to the rebreather CPU. Image from jj-ccr.com.

Are oxygen sensors trying to kill you? That depends on how old they are? Are they in date? Ignoring the expiration date on chocolate chip cookies probably won’t kill you, but ignoring the expiration date on oxygen sensors may well prove fatal. Complex systems like rebreathers depend upon critical subsystems that cannot be neglected without placing the diver at risk.

Oxygen sensors are usually found in triplicate, but if one or more are going bad during a dive, the diver and the rebreather can receive false warnings of oxygen content in the gas being breathed. We have seen a rebreather computer “black box” record two sensor failures, and it’s CPU logic deduced that the single working sensor was the one in error.

The controller’s programmed logic forced it to ignore the good sensor, and thus the controller continued to open the oxygen solenoid and add oxygen in an attempt to make the two dying sensors read an appropriately high O2. Eventually, the diver, ignoring or not understanding various alarms he was being given, went unconscious due to an oxygen-induced seizure. His oxygen level was too high, not too low.

Unlike fuel for a car or airplane, you can have too much oxygen.

Oxygen sensors do not fail high, but they do fail low, due to age. Rebreather manufacturers should add that fact into their decision logic tree before triggering inaccurate alarms. But ultimately, it’s the diver’s responsibility to examine his own oxygen sensor readings and figure out what is happening. The analytical capability of the human brain should far exceed the capability of the rebreather CPU, at least for the foreseeable future.

2016031295100655 — JAKSA high pressure 6-volt solenoid used in a Megalodon rebreather. NEDU photo.

Oxygen addition solenoids hold back the flow of oxygen from a rebreather oxygen bottle until a voltage pulse from the rebreather controller signals it to open momentarily. The oxygen flow path is normally kept closed by a spring inside the solenoid, holding a plunger down against its seat.

But solenoids can fail on occasion, which means they will not provide life giving oxygen to the diver. The diver must then either manually add oxygen using an addition valve, or switch to bailout gas appropriate for the depth.

Through either accident or design, divers have been known to invert their solenoid spring and plunger, thereby keeping the gas flow open. In that case, oxygen could not be controlled except by manually turning on and off the valve to the oxygen tank. Of course, knowing when oxygen is too low or too high would depend upon readings from the oxygen sensors.

Suffice it to say that such action would be extremely reckless. And if the oxygen sensors were old, and thus reading lower than the true oxygen partial pressure, the diver would be setting himself up for a fatal oxygen seizure. It has happened.

Assuming a solenoid has not been tampered with, alarms should warn the diver that either the solenoid has failed, or that the partial pressure of oxygen is dropping below tolerance limits.

But as the following figures reveal, if the diver does not react quickly enough to add oxygen manually, or switch to bail out gas, they might not make it to the surface.

The three figures below are screen captures from U.S. Navy software written by this author, that models various types of underwater breathing apparatus, rebreathers and scuba. In the setup of the model, an electronically controlled, constant PO2 rebreather is selected. In the next screen various rebreather parameters are selected, and in this case we model a very small oxygen bottle, simulating an oxygen solenoid failure during a dive. On another screen, a 60 feet sea water for 60 minutes dive is planned, with the swimming diver’s average oxygen consumption rate set at 1.5 standard liters per minute.

On the large screen shot below, we see a black line representing diver depth as a function of time (increasing from the dashed grey line marked 0, to 60 fsw), a gray band of diver mouth pressure, and an all-important blue line showing the partial pressure of inspired oxygen as it initially increases as the diver descends, then overshoots, and finally settles off at the predetermined control level of oxygen partial pressure (in this case 1.3 atmospheres). Broken lines on the very bottom of the graph show automated activation of diluent add valve, oxygen add solenoid, and over pressure relief valve. Long horizontal colored dashes show critical levels of oxygen partial pressure, normal oxygen level (cyan) and the limit of consciousness (red).

Screen shot 1 — Screen shot of UBASim results after an ill-fated 60 fsw dive.

The oxygen solenoid fails 53.7 minutes into the dive, no longer adding oxygen. Therefore the diver’s inhaled oxygen level begins to drop. Rather than follow the emergency procedures, or perhaps being oblivious to the emergency, this simulated diver begins an ascent. As ambient pressure drops during the ascent, the drop in oxygen pressure increases.

In this particular example, 62.5 minutes after the dive began, and at a depth of 13.5 feet, the diver loses consciousness. With the loss of consciousness, the diver’s survival depends on many variables; whether he’s wearing a full face mask, whether he sinks or continues to ascend, or is rescued immediately by an attentive boat crew or buddy diver. It’s a crap shoot.

So basically, the rebreather tried to kill the diver, but he would only die if he ignored repeated warnings and neglected emergency procedures.

What about your rebreather’s carbon dioxide scrubber canister? Do you know what the canister duration will be in cold water at high work rates? Do you really know, or are you and the manufacturer guessing? What about the effect of depth, or helium or trimix gas mixes? Where is the data upon which you are betting your life, and how was it acquired?

Scrubber canister and sodalime. NEDU Photo

Sadly, few rebreathers have dependable and well calibrated carbon dioxide sensors; which is unfortunate because a depleted or “broken through” scrubber canister can kill you just as dead as a lack of oxygen. The only difference is a matter of speed; carbon dioxide will knock you out relatively slowly, compared to a lack of oxygen.

But if you think coming up from a dive with a headache is normal, then maybe you should rethink that. It could be that your rebreather is trying to kill you.

Samael_(Angel_of_Death)_Personification — Samael_(Angel_of_Death)