Bluesky and Vaporware

Lab curiosities and bluesky products were some of the things we used to avoid during my tenure as a corporate guy. Sure, sometimes you needed to develop a tool or process which would never see the light of day, other than on the plant floor, and thats fine. The danger however is when you end up thinking that some bluesky thing is going to sell, and its even more dangerous if you think its going to be big. Granted, one can blow this, we had the concept of the Iphone on a bar napkin some 10 years prior to its release… we figured it would never have enough volume to get the price point down to a reasonable level.

That being said, back in the day, we had a bi=yearly push to get the catalog out to the print shop. Often times this meant we had to mock up new products well before they were complete, and in some cases well before we created a single drawing…

And then 6-12 months later, once we had a game plan in place development wise, there would always be one or two products which were just not feasible. Perhaps marketing was too optimistic on pricing. Perhaps thermodynamics threw a wrench into things mid way through. Perhaps there were mechanical reasons as to why something could never be that we had missed in our mockups.

Thus, for a 2 year cycle, we might have customers asking for the impossible… yes, we created vaporware.

And thats a common problem with cad systems. Its really easy to draw up something super cool, only to find out there are physical characteristics which prohibit it from ever coming to fruition.

Which is exaactly what I did a couple months back…. namely, when I end up with leftover and/or scrapped material, I’ll crank out a quick drawing to try and reuse it elsehwere. Most typically my scrap becomes shop tooling…

Except when I fail to consider the strength of a given used material, where things start making noise, often followed by a catostrophic failure. I’d picked up some water damaged plywood from alongside the road… and while it was no good for a customer project, I figured hey I can used this. Well, it turned out to be much weaker than expected, so evem with a modest safety margin, it went boom as soon as I started putting it under tension.

And I d

ATP Production in Cellular Respiration 30, 32, 38 ???

This is one of the easiest exam questions to answer ever… its whatever your professor told you it was. This is how you will pass his/her exam. Alas, whether your professors desired response in a reality is truly correct or not is a whole other matter.

Historically, the answer was 36 or 38 depending upon which text book one used. Contemporary thinking puts it around the 30 figure.

The disparity in numbers is primarily driven by NADH and FADH2 multipliers which come about by the mechanisms / models utilized. It seems far from  a trivial thing to exactly resolve one way or another.

The multiplier thing is intuitively hard to grasp. This video presents some of the background involved.

Its not mission critical to understanding the ratios, but one should be aware of protein complex numbering as to H+ production. I tend to believe this is correct, but a copy of it on Khanmedicine suggests otherwise…

Having spent hours on this rabbit trail, I tend to think the correction on Khanmedicine is correct… but I can also see why the videos author presented this the way she did.

A fellow student came up with the following from page 1103 of The Molecular Machinery of Keilin’s Respiratory Chain which seems to nail it. The entire article is pretty eye opening, but is more than a bit intense for those of us without a biochem background.

Electron transfer from succinate to oxygen will result in six H+ deposited outside (four due to bc1 complex and two due to cytochrome oxidase), six H+ taken up from the matrix (four due to bc1 complex and two due to cytochrome oxidase) and six charges translocated (two due to bc1 complex and fourdue to cytochrome oxidase). The majority view, although still perhaps open to possible question, is that electron transfer from NADH to ubiquinone through complex I is coupled tothe net translocation of four H+ and four charges across the membrane. The reduced ubiquinone is then reoxidized with the same outcome as succinate. Hence succinate oxidation is linked to six electrogenic proton translocations and NADH is linked to ten.

On Medical Beeping

Most medical devices have some form of audio alarm functionality to indicate a problem has occurred. Such seems an entirely reasonable and prudent thing to have… but what happens when you have 942 alarms per day in a single unit at National Childrens Medical Center in Washington DC? That’s an alarm going off every 92 seconds.

  • We know that sleep is critical for well being1… but how is a patient to sleep, or get decent sleep with that level of alarm noise?
  • We know that an alarm system that cry’s wolf all the time will in short order be an alarm that is either ignored at best, or vandalized at worst. Fortunately in medicine, folks don’t have to worry about someone taking a 12 gauge shotgun to the alarm (I saw a spec requiring a test along this line once)… but reflexively hitting the silence button without thinking is.
  • We know from aviation, that if there are too many alarms going off concurrently, its pretty likely that the most mission critical one will be buried in the noise of the trivial ones. Ie, if there are too many alarm bells during an emergency landing, the probability of missing the landing gear horn goes up exponentially.
  • In firmware engineering land, we have tons of information, but we selectively share information with the user to avoid overwhelming them. In the legal world, keeping this information hidden opens the door to liability, so the default is to alarm the user, even if its of very low importance.The other side of the coin, is that sooner or later, the legal world is going to see revenue in adverse event lawsuits due to information overload… and this will foster some serious thinking as to the balancing that needs to occur.

From a tech point of view, all of the above are easy to resolve… but it requires a system level approach will all of the stakeholders talking to one another. This is a recurrent problem for just about all large scale institutional problems. Its not the technology, its the people and politics behind it.

One of the ways device firms try to get around the people and politics issue is to provide for vast levels of user customization. Such provides for an economy of scale, but it does open the door up for liability somewhat. As a result, most firms will come up with very very conservative default settings, with the idea being a user who doesn’t configure things won’t miss an alarm function, no matter how trivial.

Consider some cardiac monitor data from Stanford University Medical Center. Over a 2 month period, they were experiencing 883 alarms per day. 43% of those alarms were non-critical, non-actional. 38% were for non-treatable events, only 19 of the alarms were code blue…2

The obvious solution to this is to be less conservative with the alarm limits… but this is tricky. Some have suggested, we need to create multi-disciplinary teams, capture a bunch of data, have a ton of meetings, draw up new specs, have a ton of meetings, and then have manfacturers develop new products, have a ton of meetings, and spend a bunch of money to solve this. Perhaps in the future, we could have the alarms automatically customize themselves off the patients trending data. In other words, its a time and money problem… but wait.

Frank Block says: We discussed at the AAMI Alarms Committee that this technology not only exists, but it has been incorporated in most ICU Monitors for the last decade. In other words, the clinicians who asked for this feature almost certainly have that feature today…but people don’t know the features of their own monitors! (And they don’t know how the alarms work, or how the alarms are supposed to work, etc.)2

Yep…. There is not much new under the sun. The same politics that leads to unwashed hands, and jokingly inadequate infection control is likewise a driver of beep mode. This is not to the moon type stuff to solve technology wise, but it certainly is people wise.

As far as how to fix this… visibility of the problem on all sides needs to be out in the open in a huge way. The system as it stands does not, nor will it tolerate such in part due to liability and/or license revocation concerns. No one wants to fess up about a patient dieing as they hit silence when they shouldn’t have. Likewise, no one wants to fess up to missing a critical alarm as they were jugging 10 others. Patients make lots of noise, but no one who can effect change is hearing. In a lot of ways, this was how aviation was run up until the mid 70s when ASRS came into being.

As aviation and medicine are worlds apart, I’m not if this would work… but a similar program which grants immunity to reporters and encourages sharing might be a good step forward to resolving this.

1. Sleep disruption due to hospital noises: a prospective evaluation.

2. AAMI Clinical Alarms Summit 2011

Kickstarter Margins

I’ve been looking at failed kickstarters and a recurrent theme seems to be one of playing the big boys game with a beer budget. I get that everyone wants to come out with the latest widget and sell it for $99.99 in order to capture market share. Such can work wonders if your volume is really high… but what if it isn’t? What if your kickstarter maxes out with a couple thousand backers? What if your price point is $200 (double msrp, being these folks get in on things from the get go, and you throw in some swag to sweeten the deal).

At the end of the kickstarter, you have $400K to work with… but how far can that really go?

With an MSRP of $99.99, your direct costs related to manufacturing (BOM+manufacturing labor+amortization of tooling, fixtures, etc across 2000 units) has to be $30 or less, ideally a lot more like $15 for lower volumes. Alas, since your kickstarter has a price point of $200, you have double those figures to work with… in other words, a target (BOM+manufacturing labor+amortization) with an absolute maximum of $60, with a $30 target providing a much safer cushion.

And here is where the problem lies, a (BOM +manufacturing labor+amortization) figure of $30 doesn’t get one very far. In fact most smaller products when costed out at Mouser or Digikey at 1K prices are going to be more than $30 alone, to say nothing of the costs of labor or amortization.

This is where folks get into trouble…

1. We don’t need to make a profit off kickstarter, as long as we break even, we will be happy. After all, once we start selling 50K of these a year, money will be rolling in… so its ok, if the margin drops from 6.6… after all, the big boys will let it roll all the way down to less than two. The problem with this thinking, is that the big boys have millions to back up non-recurrent engineering, development and fubar. Kickstarter folks, unless independently wealthy don’t… for every decrease in margin, the development budget shrinks.

2. Our offshore vendor says they can turn key this for $60 as they can leverage the scale of their large volume customers, and or procure parts at bargain basement prices through their vendor network. This can and has worked wonders… but what happens when the large OEM you are leveraged off of changes course? Do you have the resources to do a major redesign midstream, and/or delay some of your customers delivery for months while such is ongoing. What about having to go to the gray market for critical components?

3. A 6.6 multiplier seems really greedy… and it does, until you get in a shipment off the boat with a 80% failure rate and the vendor doesn’t stand behind it. Your customer doesn’t care about that, all they want is a product that meets spec at the time you promised. Do you have the resources needed to rework the units on shore, and/or rip up and redo from the get go.

4. When investors see our sales, we will be able to raise the funds necessary to make a go of this. In some situations, this can work and may be the only saving grace of a given kickstarter project… but they will step in only if the numbers make sense. (Ie, an investor will take a dim view of you giving away $200 with each unit you sell, unless its only a tiny and easily fixed step to profitability). In addition, when you add in investors, you loose control. What might have been a focus on idealistic sharing with the community becomes a potential competitive threat once investors step into the fray.

Such is why bargain basement hardware development, low multipliers and a low target msrp set the stage for failure. It takes a ton of resources to do this, even with highly experienced individuals running the show. There is always a murphy waiting around the corner to bite, often in a huge and unpredictable fashion.

So whats the answer?

Low msrps and lower margins are probably ok if you are already in low levels of production, ie, you can already build hundreds a year by hand, sell them, and break even, you just need high volume production tooling to truly make a profit. However, this is not the time for scope creep. Do that only after your revenue stream is positive and solid… too many things die on the vine as its only a tiny mod, and we will sell a ton more, and end up selling none.

If your volumes are low, and/or you are testing the market, let the MSRP and kickstarter rewards remain high to protect both you and your customers. Once volume production kicks in, you can always drop prices and/or provide freebie upgrades to existing customers who paid 3x or more the volume msrp. Obviously there is an issue of competition and or pricing oneself out of the market… but better to do that than loose your as well as your customers shirt.

Olfactory Illusions, Dissections, #Vitalsignsmooc #neuromooc

WARNING: Dissection images/videos may not be suitable for younger folks, and/or those with sensitive dispositions. Fair warning, I’m not buying folks new keyboards as they lost their lunch.

Yesterday I went full bore into virtual dissection mode. The first thing I rolled on was the sheep brain dissection in #neuromooc. It was fascinating to see the similarities between the sheep brain and the human brain.  So much so, I must say I’m tempted to go order one as Carolina has them for under $20. Alas, I’m only tempted lol, I’ve got so many irons in the fire, dissecting a sheep brain would end up pretty low on the priority list, and it could sit in a box for ages.

Then again, I’ve explored a human one in the past, albeit it was a short course put on my med students and sadly I’ve forgotten a ton of it. Alas, a few things really did really stick with me,  one item especially. Perhaps it might be better said, stuck on me, and through me. Namely formaldehyde. I could smell it for days after leaving cadaver lab… its like there was this cloud of vapor, and it embedded itself in your being. No amount of cleaning, showering, shaving etc would get rid of it. Even my car smelled like formaldehyde.

And there in lies the rest of the story, but stand by for just a second while I fill in yesterdays background.

My cardiac anatomical knowledge is really shakey, I can go ok, so the left ventrical is here, and oh yes, this is the mitral valve, and left atria, there is the aorta…. but its not bing bing bing automatic. Thus, after the sheep brain dissection, I went searching on youtube for a heart dissection.

Alas, unlike my memories of a human heart where great pains were taken to keep the valves intact… the youtuber sliced right through them… which was not what I was hoping to see. Thus a little more digging, a few more videos, and I ended up here.

All in all, I spent about 3 hours viewing heart dissections from a multitude of places… and it does help. I’m still not 100%, but I’m not crashing and burning if the heart is presented in other than a coronal frame of reference.

However, about 2 hours in, I started smelling formaldehyde. I do not have any formaldehyde here… and then the odor got stronger and stronger, to the point it was like egads. Now the interesting thing was, when I got up to go look outside to see if there was a formaldehyde truck crash or something, the smell went away in a flash. Apparently my brain was playing tricks on me and somehow transporting me back to cadaver lab.

Yep, cadaver lab is intense… I mean the dude whose brain you are holding was alive less than 6 months ago. There are all sorts of crazy emotional stuff that goes on in day 1. I didn’t remember the names… but I sure remembered that the dura was like an armor. I remember the horse tail (cauda equina) comes across as nearly an alien life form, and nothing like what I’d seen in the text books. Alas, despite the intensity of all the human body bits, the formaldyhyde was what played a game with my brain.

A couple links on olfactory illusions:

#VitalsignsMOOC Week2 on Cardiac Stuff

This week flew by as the amount of new material was pretty limited. The quiz came out today, and I blew through it in about 5 minutes, getting a couple wrong because I didn’t read them properly. That being said, there is a huge boatload of information to reinforce from last week and a few cool rabbit trails.

I find that my knowledge of heart anatomy is still not at the point of being instantaneous. I’m having to look and think as to what the parts are, and thus more practice is needed. I did come across a most fascinating video from khan, where in they are viewing the heart from a patients perspective looking down into the chest. The interesting thing, albeit obvious point about this view is that it inverts the geometry left/right, in contrast with the anatomical view (coronal) I learned last week. I’m thinking multiple planes of view, both from the patient as well as the anatomical planes may prove beneficial as means of studying anatomy.

Being imaging studies reference the standard anatomical planes, I wonder if the observer (standard anatomical) vs patient reference frames might have played a role in the rapid prototype error discussed in the TED talk entitled how I repaired my own heart.

Hemodynamics has been bugging me to no end… and this graph is less than helpful.


The use of a linear Y axis completely buries pressure deltas starting with the capillairies and continuing on throughout the cardiac cycle. Alas, digging for a semi log plot of such to bring out the detail seems an exercise in frustration. One interesting bit to consider is the increased frequency in the arterioles, it appears to have doubled, but I’m not sure if that’s an artist error, or if muscle activity from the Tunica Media actually causes this.

Alas, the graph is helpful in one regard, as the first derivative clearly shows that aterioles are the major playing in decreasing pressure such that capillairies dont blow. This is graphical hand waving calculus… I’m not sure how you create a derivative with respect to a sequence of nouns. 🙂

That being said, I remember a post by @atdiy where she talked about a no beat heart, and some ideas as to why patient quality of life takes a header with a LVAD. Its a most fascinating read. See below for a xray of a no beat heart from

Getting back to a beating heart, I did find the following video of interesting. The author presents pressure variation where the supervior vena cava enters the atria. Its a rabbit trail for sure… but as I expected, there is massive variation in pressure (well massive from the point of view of heart action dicks around with the pressure) but not massive at all relative to the mean arterial pressure at the aorta.

Lastly, I managed to get a bee in my bonnet over what the professor said about mean aterial pressure referring to mean as an average… a moving average perhaps, but not an average of diastolic and systolic pressures. I did find an approximation formula which makes sense at .

Pm = 1/3Ps + 2/3Pd

@VitalsignsMOOC first week thoughts cardiac stuff

This is proven to be an interesting class so far. Initially I thought it might prove too simplistic and certainly the gaps between clinical practice, medicine, academia, and engineering are huge, but its cool seeing things from another sectors point of view.

A few thoughts:

Plastic heart models are pretty sucky… but then again everything is a compromise when it comes to models, and even more so plastic ones. 🙂 Had I not had experience with pacers, the models would seemingly create a ton of disconnects… but cadaver lab on day 1 would likely be too intimidating, so I guess plastics models are a reasonable compromise. Alas, we do have youtube, and spending an hour viewing an open heart surgery reinforced a ton of material.
Human Heart from wikipedia

Wiggers diagrams are incredibly helpful to understand the the cardiac cycle. Alas, there is a lot of information where in google is less than helpful. This is probably due to my rabbit trailing outside the scope of the course…

Things like the dicrotic notch and wave explanations are crazy from an engineering point of view. If measured right at the aorta, one would have the expansion of the aorta as well as the impulse response of the aortic valve and reflected waves returning from other structures.. short of something being highly tuned, my gut feel is some level of ringing would occur in this. On the other hand, if the aorta pressure is measured further away from the heart itself, one would also have reflected fluid momentum playing havoc with the measurement. Is this damped by the elastic nature of the aorta? Are there chemical processes dicking around with the aorta’s modulus of elasticity? What about the degradation of the aorta and valves over time? Alas, these are questions outside the scope of the course.

Heart sounds are tricky and the teaching of them apparently more so. We heard one example, and even after cycling through it a few times, it was still a bugger to pick up the difference.  Alas, youtube was friendly in this case.

This video covers locations in a cool way… marked up tshirts 🙂

This doctor is incredibly entertaining and he takes complex material and makes it simple, in this case location as well as sounds.

We still have the issue with what on earth are these things supposed to sound like? Alas, a helpful person in the forums shared the following link which presents mp3’s of a number of problems.

ECG’s were briefly touched upon with one bit being that a 12 lead ECG only uses 10 electrodes. In electronics we have conventional current and electron flow… which causes no small amount of confusion as they are reversed.

In medicine it seems everywhere you turn there are legacy terms and some insane need for backwards compatibility that creates endless amounts of circle chasing. Do we really need 3 names for the left atrioventricular valve (bicuspid, mitral). Do we really need to use the term leads when its really a mapping of the electric fields in different planes of reference? And whats with the chart recorder legacy stuff? Such is why I’m not in medicine LOL

A fellow student provided a link to a cool ECG trainer / simulator…

AV Node delay timing in response to exercise is crazy stuff… I remember some of this from pacer discussions, but just as there was ambiguity back then, it appears its still quite vague today. (Tone plays a role such that sometimes it need to roll forwards in othertimes reverse. Granted, this is outside the scope of the course… but seeing the AV node time mention as 0.1 sec brought back memories. Iirc, it was just a tad over that figure, but there are many ways to look at it… AV free running rate is tweaked 20% if memory serves.

Evaluation A multiple choice test was used for purposes of evaluation. The questions were reasonably easy, but did require some level of thought rather than just the parroting back of information. The ultimate test of my knowledge will be if I can draw and annotate a human heart, draw and explain a Wiggons diagram, identify heart sounds, and interpret ECG traces in May 2015. I can do none of the above to 100% correct standards currently, as such requires more practice then a few hours of videos and studies will provide for… but such will be my means of review of the course material to prevent forgetting it.

All in all an interesting class this week. Next week is on blood pressure. I wonder if we will learn the history of the old wives tale of salt bringing about high blood pressure. Its an interesting myth with a tad of truth mixed in just enough to create lots of confusion.

Learning Physiology in 2014

Over the years I’ve worked on a variety of medical products. Everything from chiropractic gear to blood analyzers to pacemakers. As a result, my knowledge of physiology is scattered all over the place, from jr high school knowledge to somewhat deep, but only in very narrow areas.   As I’d like to have a broader knowledge base, I’ve signed up for a number of MOOC classes across a range of disciplines.  Granted, a MOOC experience will never bring about the same as one might get in a in-person classroom with lab experiences with live, or recently alive bits. On the other hand, I’ve gained a fair bit of knowledge over the years work wise, so it will be interesting to see how the pieces fit together.

Electricity is no Respector of Man’s Codes

Electricity is no respecter of the NEC or any other regional code for that matter. Electrical codes try to ensure some level of safety but are compromised due to political and economic factors. Codes also change over time, due to bad experiences, lessons learned, as well as changing political / economic factors. Alas, this does not mean they should not be ignored, there is a much good advice within. The danger comes into being when they are viewed as some sort of divine truth.

A common problem in older houses is that most of their electrical outlets are 2 prong thus lacking the ground connection. There are many ways folks try to mitigate this shortcoming, some of which pose electrocution hazards, some of which pose fire hazards, and of course the right way which equates to ripping things to bits and starting over.

The most common approach is a 3 to 2 prong adaptor which is rarely if ever used properly. The little grounding tab is supposed to be connected to ground via an outlets center screw… alas, many boxes are not grounded.

1. Many years ago, BX cable (basically 2 wires surrounded by a spiral metal shell) was commonly used. On a positive note, the spiral metal shell sort of provided a ground path between an outlet box and the main panel. By sort of, it provides a path such that a 3 light outlet tester would likely indicate the outlet was grounded. Alas, under a serious fault condition, the spiral metal sheath might not provide solid enough ground connection to trip the breaker… in some cases, the breaker would not trip, that is until the spiral metal shell turned red hot and melted the insulation off the wires shorting them together and in some cases starting a fire in the wall. (BX has not been sold for many years as it was replaced by AC cable (which looks the almost the same but has a continuous ground specifucally designed for fault currents)

2. The use of a GFCI as a workaround is a legal short cut, and it can serve to mitigate shock hazards. Fire hazards are another story. In some future versions of the NEC, I fully expect this practice to be made illegal, just as the old school means of grounding via a water pipe or single wire to another ground circuit were made illegal. (The NEC does allow one to run a single ground wire back to the main panel, but its vagueness as to wire routing / protection makes for a fire waiting to happen depending upon the installer.)

On Common Core Math

The idea of common core math is to develop understanding, rather than superficial rote methods in the interest of global competition in STEM and related. The problem with this ideology, is that for the majority of folks out there, getting the right answer quickly rather than really understanding whats going on under the hood makes no sense.

Consider these 4 students and how parents would respond.

1. Little Bobby doesn’t show his work, but gets the right answer. He gets a low grade as when queried, he embraces rote methods with very little understanding of what he is doing.

2 Little Suzy shows her work, makes a mechanical error in writing mid way through the exercises using a unique method,but gets the answer wrong. She gets a higher grade than Bobby as she shows understanding of the process.

3. Little Annie who shows her work and gets the right answer. She gets a higher grade than both Bobby and Suzy, but her approach is purely mechanical. She only uses the methods a given teacher uses over and over, and freaks out when her plug and chug doesn’t work.

4. Little Joey shows his work and gets the right answer. He gets extra points, as he is using a number of methods to get the right answer. He may not always choose the optimum approach, but is demonstrating a deeper level of understanding across a multitude of approaches.

The global competition ideology is the following.
On the job site, little Bobby and Annie will build bridges that if they deviate very far from what he’s seen before will run into trouble. They are likely to be relegated to mundane work. Suzy while potentially error prone if paired up with someone to verify her work is likely to push the envelope. Joey is likely to do well no matter what or where he goes. Global competition suggests we need a lot more Suzy and Joeys than we need Bobbys and Annies… The status quo says Bobby’s and Annies should rule, that is until they are run over by the competition.

The status quo is that 99%+ of society uses rote, and short of a few math nerd teachers, very few outside of some STEM sectors have a rock solid math foundation… This sets the stage for examples like this  to propagate which just adds insult to injury.


The above is a terrible example of a decent method. Such is commonly used for doing mental math with large numbers, fractions, and even mixed unit problems like time/date calculations. Mental math while useful to solve equations in mid sentence is a cool and at times a useful thing… but the intuition developed from doing so is where the economic value adder really comes into being. Ie, computers, math models, simulations are all good things, but you must have a pretty good idea of what the answer is before you begin or you will shoot yourself in the foot.

Such is pretty common among the majority of STEM folks I’ve worked with over the years… (and many older tradespeople as well… I’ve known retired carpenters, bricklayers, and machinists who can run math circles around some recent engineering grads who are lost without their computer models.) More often than not, such is the result of having to throw out rote math concepts and rebuilding a foundation from scratch… or in the case of oldsters, because using a slide rule pretty much mandated a solid foundation if they wanted the cool projects rather than the mundane.

I’m not a teacher, but the idea of a firm foundation rather than quick and dirty methods which have to be unlearned later makes sense… Alas doing so goes against the grain of society, many parents who will have fits with low grades for Bobbys who still get the “right” answer, and some suggest that math understanding is too advanced for young kids and that rote should be good enough. I don’t know what the answer is… but hiding ones head in the sand has generally proven not to work out all that well.