Grand scientific study of Covid testing for triple vaccinated people (sample size = 1, 16 Feb 2022)

It’s been a while since I wrote on my blog but I figured let me share this personal example, and my two conclusions right away:

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My 2018 Christmas Eve project: resurrecting my HP41CV

Sometime in high school in 1979 or 1980, I bought my beloved HP41CV. The first programmable calculator with alphanumeric display and, of course, reverse Polish notation. It’s got Wikipedia entries and has become a collection item, fetching multiple $100s on eBay.

Since leaving Belgium in 1989, I faithfully moved the calculator with me but forgot to take out the batteries. Even when I put new batteries in, the display did not come to life. Then I resorted to the place with all answers: Google and YouTube. And I found this great YouTube video titled “HP 41CV calculator repair of bad battery contacts.”

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Did my cycling power really increase this winter on my Wahoo Kickr? Power accuracy and thermal drift on my Kickr

Do you train using a Wahoo Kickr that is in your garage or in a colder area like me?
I probably bought one of the first Wahoo Kickr’s in 2014 and was a beta user on Zwift. The Kickr is awesome and has brought me a lot of joy except …. for the finicky power readings who tend to deviate, sometimes substantially (30 to 50W) from my crank Quarq power meter. When I got my Kickr, I even got the mechanical calibration kit but all seemed ok. Then I got into Zwift group rides and races and forgot about the power discrepancy reported by my Kickr.

This winter, however, I decided to adopt the Zwift 12-13 week FTP builder protocol. To start I did the Zwift 20min power test with my Kickr controlling the resistance in Zwift. I know my FTP falls in winter and when testing indoor, yet I was so happily surprised: this was my first 20min indoor test during which I wasn’t dying or thinking of giving up AND the numbers were better than expected.
That is: the numbers reported by the Kickr power meter. Unfortunately, my Quarq reported quite different numbers (see Fig 1).

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Should healthcare prices be regulated or free?

Behind this article in The New York Times is an interesting question alluded to in its final paragraph: should health care prices be regulated or free?  PhD dissertations and books are written addressing this intricate important question that can’t be done justice in a few paragraphs but I couldn’t help my mind from wandering as follows:

Capitalism and free market economies have one great virtue: the invisible hand that sends information (through prices) to those activities and their actors that are valued most.  The latter can be quantified by the aggregated willingness to pay (WTP) of people, which is the upper ceiling on the price they are willing to—and can—pay for those activities. As such the prices in free markets direct resources in a decentralized manner. And economics 101 tells us that under perfect competition the resulting market price leads to an efficient equilibrium between supply and demand. Simple, yet remarkable.

The rub, of course, is that this holds under perfect competition and in equilibrium for society at large, not for each individual.  Humans tend to form coalitions to preserve and even better their lot (by preventing perfect competition and efficient equilibria :).  And even an efficient market equilibrium does not regulate the distribution of its efficiently produced value.  As we are witnessing (one century after the previous excesses that led to “cottages” in Newport, for example), this can lead to a widening of the income and wealth distribution, and even to a “winner takes all” equilibrium as in sports and technology markets.  Like some of you, I am benefitting from the fact that the willingness-to-pay for health care and education is so large, especially parent’s WTP for their children reflecting the perceived lifetime value they are to receive from those activities. (Technological gadgets like iPhones also seem to command high WTP, even for short-term value 🙂 I keep being amazed during my travels seeing kids run with smart phones in their hands and workers watching their gadgets on the job…  This observation is no longer surprising, but it is surprising how this so quickly—in one decennium—became a global phenomenon.  No wonder Apple is the highest-valued company…)

I admire, and subscribe to, the benefits of free market efficiency.  But even an “efficiency (wo)man” hopefully realizes that life is not only about efficiency.  Life is to be lived… decently so that we can all go to bed at night feeling that we did our best today and would not mind seeing our activities communicated to the public.  To me, this means that as a society we should also pursue the decency to provide a reasonable level of health care for all.  Therefore, capitalism is to be augmented with some restraints and regulation.  Paradoxically, perfect markets require protection against the human tendency to form “coalitions.”  The perennial question is: how much?  That balance will always move over time, reflecting the relative power of the various constituents that (can and are willing to) vote.


Or am I naive?
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iPadPro Apps & Tricks for Handwriting: Note-taking, Communicating and Teaching

Here are some apps and tricks that may be useful for handwriting.  (Please do comment or add so we can share how to utilize the iPadPro effectively. Another blog focuses on the iPad for research.)

Handwriting apps

There are many apps for handwriting. Two dedicated apps that work extremely well with the Apple Pencil (i.e., hair-fine precision and hand palm rejection) are:

Goodnotes shines with the Pencil, saves handwriting in PDF, and hence stores handwriting as vectorized images that looks sharp at whatever magnification.  It is intuitive and even allows surprisingly accurate searching your handwritten notes.

The only thing I miss in Goodnotes is a good visual structure or overview of its “notes”.  Yes there is a three (even four)-level hierarchy: you can make “Categories” (say Courses), subset categories (for lack of better words, say Course-OPNS430), which then hold “Notebooks” (say Class 1 in OPNS430).  It works, I guess, but from an organizational perspective, I prefer OneNote (Microsoft) which I described here.  OneNote also syncs flawlessly with your Mac, iPhone and PC.

Communicating (over Skype)

A simple, free and effective tool is showing whatever you do on your iPadPro onto a window on your Mac (using no special app, only the free built-in QuickTime in OS-X and your Lighting-USB cable).  Here it is explained (it takes < a few seconds):

Why is this useful?  Using Skype on the Mac, you simply share that window (I don’t think the Skype app on iPad allows you to share another app on the iPad) and now you can draw or annotate on your iPadPro and the other party can see it all.  It’s like sharing a white board. Of course, if you use OneNote or GoodNotes or so, you can save annotations into PDF at end of the call and share them.  [You can also save the QuickTime recording, but mostly I would just discard it.]

Presenting and Teaching (in the classroom)


You can use QuickTime as described above in the classroom: If your Mac is connected to a projector, you can maximize the QuickTime window and simply project that to show whatever is on your iPadPro.  [I know you can connect your iPad directly to a projector with the right dongle, but now 1) you don’t need the dongle and 2) you can stay within the “safety” of projecting from Mac and only swap a window when needed to show iPad].

The above allows you to use and “project” any app, including Powerpoint, GoodNotes, PDF Expert.  Of course, you can do it without the Mac by using a dongle.

A more controlled method to project directly from iPadPro is to use 2screens which works well for pdf and webpages. You can have several presentations loaded at the same time and switch from one to another. And: it has a companion app for the iphone that has a good userinterface, you can switch jump slides, you can have a pointer, …

So if you present from PDF, 2screens may be your baby.  While 2screens can also show ppt, “animation and transition effects in Keynote/PowerPoint are NOT supported.”  That means that I can’t use 2screens (as my presentations are in PowerPoint and often use animation and transitions.  The iPad Microsoft Powerpoint app works well as long as you stay tethered and near your iPad while teaching.  I like to be mobile while teaching so the only thing I am missing to teach solely using the iPadPro is a clicker.


The mobile concern will be resolved in new classrooms that support Apple Airplay so you can walk around with iPad in hand.

Another option (I was told but have not tried yet) is to use which allows you to wirelessly mirror your iPad on your Mac (or PC), which then can be used for skype or be attached to a projector. No cable connection needed so you can walk around with iPad in hand.


Posted in Academia, Research, Teaching | 2 Comments

iPad Apps & Tricks for Research

Here are some apps and tricks that may be useful for researchers.  (Please do comment or add so we can share how to make the iPad work well for research. Another blog focuses on iPadPro for handwriting.)

Sync & store local files on iPad and directory structure

It may be old-fashioned, but I do like off-line access to my files.  There must be some iOS restriction so that cloud storage providers (e.g, Dropbox and OneDrive) cannot just make local copies of entire directories onto the iPad. Using Dropbox and OneDrive you are restricted to selecting individual files (one-by-one) and clicking “Make Available Offline.”  (It would be AWESOME if Dropbox and OneDrive would simply, by default as they do on Mac and PC, make local copies of entire folders and sync whenever connected to the Internet, but alas…).

The free app Document (by Readdle) provides a solution: it connects to your cloud storage apps and you can click entire folders and click “Sync” in upper right “to enable two-way synchronization.” It will automatically include subfolders in the sync.  GREAT.  The app also views many file types, including media files.

Annotating PDFs

There are many PDF apps that may work well for you. After I found Documents, I got hooked on PDF Expert. This $9.99 app is also made by Readdle and integrates flawlessly and uses the same file structure (including directory synching).  In addition to usual text markup (in all ways you can imagine), it also works perfectly with Apple Pencil for beautiful pen markup. So it meets my two objectives: easy file management and handwriting.

Organizing research ideas and projects

If visual file structure appeals to you, consider Microsoft OneNote. I love the 3-tier hierarchical structure: I have a Notebook for Research, Teaching, Seminars and Service. Within each notebook, you have various folders (say one per course that you teach).  And within each folder, various pages (say one per class of your course).  It synchs automatically over the cloud with your iPhone and Mac, and with PC.  And handwriting works fairly well.

Writing research articles in Latex

Cloud and web-based Latex tools like ShareLatex work well on the iPad. If you also want off-line access and compilation, consider the $15 Texpad.  A nice feature is that it connects and synchs to one specific Dropbox folder. In Texpad, I clicked “dropbox” on left side, and clicked “+” to write a new simple test *.tex on iPad.  This directly created the folder \Apps\Texpad on Dropbox and everything syncs automatically.  Thus, just move your active *.tex files to the root directory Apps\Texpad in your Dropbox folder. Colleagues told me that the Mac version of texpad is also excellent.

Posted in Academia, Research, Teaching | 2 Comments

First day of regular check-in process at Brussels Airport

I just arrived at Brussels Airport an hour ago and figured I share some experience of the new check-in processes at what used to be Europe’s most convenient airport.

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Sinus Bradycardia, Life Insurance, and Cycling

A short interruption of my dormant blog state to share a new learning.  Recently I looked into changing my life insurance policy and underwent a physical exam as part of the qualification.  A professional came to our house and administered the typical various common tests, including an EKG.

Today I received a letter from the insurance company stating:

After careful review, we are sorry to inform you that we have found it necessary to postpone this application.  The reason for this decision is as follows:

  • Cardiac Studies – EKG with significant sinus bradycardia.

Such letter gets your attention…  I quickly looked up “sinus bradycardia” (thank you Internet!): two Greek words “Bradus” = slow; and “Kardia” = heart.  “Sinus” is Latin and you recall from math that sinus = wave, rhythm. So there you have it: (abnormally) “slow heart rate,” which apparently is anything below 60bpm, as for “most people, a resting heart rate between 60 to 100bpm is normal.”

I started feeling better…  Sinus Bradycardia can be a sign of fitness and being well trained.  My resting heart rate is about 42 (and it’s a great marker of fatigue: it was 49 on Monday after two intense weekend rides–each with TSS of 200+).

When I forwarded the letter to my agent, he wrote:

Hi Jan,

I found out early last week and that is when we went to bat for you and had the chief medical director review the case and issue you the preferred policy at the lowest rate possible – so everything is taken care of.  You can recycle that letter!

All’s well that ends well…

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Dreaming of the Dolomites: pump or CO2 cartridges?

It’s another cold winter in Chicago.  Dreaming of my trip to the Dolomites end of June is all I can do.  Given that it won’t be a race, time to inflate a flat really isn’t a factor so I’m thinking of carrying a pump instead of cartridges.

Of course, the overriding decision factor is weight.  So I’ve put my new Lezyne test up to the scientific test and it wins by 21g.  Yahoo!  Added bonus: the pump can fly with me (on the airplane that is) while cartridges cannot.

2 cartridges and inflater = 114g

2 cartridges and inflater = 114g


My new pretty Lezyne pump is exactly 93g as advertised!


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There is no free lunch on Ventoux

Brilliant day in Bédoin: perfect for the ride with Gerry that we planned on a few months ago. Given that we hadn’t been any more specific in our planning, Gerry asked this morning “so what are we going to do? A ride or…?” Well, here we are 1min from the official start of the Ventoux climb so “let’s do a strong climb and then we see what we do from the summit,” I said. Gerry needed no more arm twisting 🙂
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