The Haversian Canal

Atul Gawande has a Perspective artice in the 23 March edition of the New England Journal of Medicine. This entry's a bit late, but I actually wrote it in my notebook first. And the blog is looking a bit sparce here. Gawande's article is about the Morales deathrow case in California. The ruling came on 14 February that Michael Morales could be executed only with the supervision of an anesthesiologist. 37 days later Gawande has 6000 words. That eight pages of ten point font. And you know he cut some out. If you write, you know somebody, even the author, did some editing. The article follows a clear progression, and is well-ordered, though the only demarcations are five horizontal rules: introduction with background—first vignette—second—third and fourth—fifth—conclusion or call to action (I'm not sure which). 6000 words.

About the same time Tulane's History of Medicine Society announced its annual essay contest. I'm going to interview Dr Weisberg on Wednesday. The essay is due on 1 May.

One of the second-years put out a call to for a road ride this morning, to kick of a weekly Tuesday, Thursday, Saturday routine. I raced in college and ride my bike to school, so I was game. Plus, the seven thirty start time ensured I'd get up early. I really do my best on about six-and-a-half to seven hours of sleep, but the thought of studying just isn't enough to get me out of bed. One reason I suppose I preferred morning classes. Anyway, thirty miles, on this route, and it was so nice. Steady 19 mph pace, good heart rate, mixed road conditions, though generally smooth asphault. There was a two- or three-hundred yard section that was Paris-Roubeux rough but the pavement was heaven compared to the Fort Worth armorcoat.

I do need to work with these guys on pace-line technique, but we'll get there.

From a reliable source: contrary to a 1991 JAMA study published by a neurologist in New Jersey, there appears to be a looming shortage of neuro docs. In particular the VA is coming clean that they don't need more family practice physicians. They need more opthalmologists, neurologists, and neurosurgeons to cope with the aging population.

Republication. Hah! I kill me. . . Too many ways to have read that. . . Anyway:

I often comment on Edward Tufte's forum. My comments, like those of many others, are often deleted. I think he even deletes some of his own comments. Some comments I want to keep around though. Here's an edited version of some of my recent comments on his thread about formalizing photographic aesthetics.

Here's the first article google searching for dynamic range ccd velvia: Photoshop for Astrophotographers:

Different recording media can accommodate a variety of dynamic ranges. Early model consumer digital cameras could capture detail in a brightness range of only perhaps 3 to 4 F/stops and the latest models can record about 6 F/stops. High contrast transparency films, such as Kodachrome and Velvia, can capture about 5 - 6 F/stops. Color negative film can capture 8 or more F/stops of usable detail if correctly exposed.

Note that if we measure the actual optical density of transparency film, there will be more optical dynamic range from the absolute blackest black (the D-Max)to the absolute whitest white (totally transparent) than recording dynamic range. This optical density range is greater than the range that the film can actually record detail in, so the effective useful recording dynamic range is less than the optical density would indicate. For instance, Kodak's Kodachrome has a D-Max of about 3.7, which is almost twelve stops, but its usable dynamic range is only about six stops.

Astronomical CCD cameras have a dynamic range of about 10 to 11 F/stops.

Thom Hogan reports about 7.5 stops dynamic range with the D100 or S2. If Fuji's claims are correct, then they're realizing about a 3 stop (400%) improvement. However, it's not at all clear to me that those 3 stops can be realized in prints, even from an Epson printer. I'm even more pessimistic about CMYK.

There are also certain visual deceits the visual system plays on the rest of the brain in real time. The eye very quickly changes aperture, by dilating the pupil, based on what part of a scene falls on the fovea, the very central high resolution optic disk, which is only a couple millimeters across. The subconscious also considers the ambient light of the entire scene. There are other control systems for enhancing visual acuity, inhibitory surround being the classic example. It increases contrast through neuromodulation.

Some additional articles by Roger N Clark and others have some interesting tidbits. I found them with the search dynamic range human eye stops.

One last one, and I'm done. From the Wikipedia:

At any given instant, the retina can resolve a contrast ratio of around 100:1 (about 6 1/2 stops). As soon as your eye moves (saccades) it re-adjusts its exposure both chemically and by adjusting the iris. Initial dark adaptation takes place in approximately four seconds of profound, uninterrupted darkness; full adaptation through adjustments in retinal chemistry (the Purkinje effect) are mostly complete in thirty minutes. Hence, over time, a contrast ratio of about 1,000,000:1 (about 20 stops) can be resolved. The process is nonlinear and multifaceted, so an interruption by light nearly starts the adaptation process over again. Full adaptation is dependent on good blood flow; thus dark adaptation may be hampered by poor circulation, and vasoconstrictors like alcohol or tobacco.

There is also the phenomenon of bleaching: to much light can overwhelm retinal pigments. Thus the spot after staring at a bright light or a white paper looking faintly red after staring and a green sheet of paper.

20 stops of resolution seems enormous to me. Racing mountain bikes in forested areas, one experiences some tremendous variations in light, ranging from the darkness under the edges of roots to full sunlight in the same "frame", all at 3 to 30 miles an hour and looking with a central axis of the visual field regularly, forcibly, ranging between 45 degrees above the horizon to 45 degrees below the horizon. Imagine a wooden rollercoaster inside a forest but with a terrible need to understand what one is seeing because there are no rails. The decision
points are coming very fast and have serious consequences. Trees hurt, but not as much as the rocks at the bottom of a ravine. The sensations of blow-out and blur are quite familiar to this crowd. I suspect the five to eight stops of dynamic range that engineers seem to have been targetting in most production films and DSLRs may hint at the working range of the eye most of the time.

Just before starting medical school I did a design project for the National Investment Center for the Seniors Housing & Care Industries. They produce 30 reports every quarter, one for each of the top 30 metro statistical areas (MSAs) in the country. It's 27 pages of statistics in 10 point font. My job was to come up with a design that would allow them to plug an enormous amount of data into a consistent, eye-pleasing format. I was particularly proud of putting upper quartile, mean, median, and lower quartile in descending order, which you can see on page 3 because they're still using my design! Go on, check it out.

Grand Rounds is up at Anxiety, Addiction, and Depression Treatments. I'm personally glad to see the tables turned: the writing, poetry, and genuflection lead and the 'hot topics' are at the end. Perhaps the internet need not always have an extreme recency bias.

I've written before about hand-writing flashcards as a two-time-winner study method because they increase reptition and form a product you produce. Here are some ways that you can improve your notecards as you go through them:

• Complete both sides. I generally make the first draft of my flashcards during lecture. This is a good time to do it, because it keeps me engaged in the lecture, thinking critically, and offers many stimuli to associate to the information. However, I don't always get the question and the answer written. If I got most of it, I probably managed to write down the answer. If I didn't really get it, I try to at least write down a question. This can be a good thing. I can go back later and fill in the other half, which also makes the review a meaningful use of time.

• Annotate the bottom left corner with the subject, block, lecture number (or date) and page numbers of books and notes. The more of these you can fill in, the better. Particularly write in table and figure numbers if the lecturer indicates these during lecture. Understand these figures.

• Expand abbreviations and acronyms. This is particularly helpful if you have a helper (spouse, significant other, particularly smart pet, whatever), who can read the flashcards for you, but who may not actually understand the material.

• Write two to five questions and answers on each card. Write your flashcards in pencil and keep some of those white erasers handy. If you wrote multiple facts on the answer side, think of multiple questions to ask on the other side. This increases the number of associations you've made. Don't, however, make simple questions if you can make easy complex questions. "What's the difference between amylose and amylopectin" is a better than splitting the content into two questions "Describe amylose" and "Describe amylopectin".

• Underline keywords in the answer so your helper (if you have one) can know if your right even if you don't regurgitate the exact same sentence that you wrote in the answer. I use a red fountain pen for this. I find I can easily filter it out if I'm reading the gray pencil markings, it doesn't smear the pencil markings, like highlighter would, and, again in favor of red over highlighter, it doesn't affect the background of the words indicated.

• Rewrite questions and answers for natural language (e.g., use contractions) and active voice. There's a very simple formula for converting passive voice to active voice: "Hydrogen ions are produces by the parietal cells." is passive. Remove the linking verb, and by; then reorder the remaining components as subject, transitive verb, direct object: "Parietal cells produce hydrogen ions." Besides being shorter and more vigorous, it is more accurate, e.g., hydrogen ions may enter the stomach from sources other than parietal cells.

>

• Lay out all the handouts and lecture notes. Put the associated note cards on top of each set of handouts and notes. Look for glaring deficiencies in the piles, then go through each lecture and make sure your flash cards have all the right stuff.

• Put all the flashcards in order.

• Copy diagrams into your flashcards where you feel they add information. Keep in mind that the test will surely have more words than pictures.

• Identify the questions by placing an E, M, or H in the lower right corner of the question side, opposite the subject and lecture notes (see above), for easy, medium, and hard, respectively.

• As you get closer to the test, review all the flashcards and set aside the ones you obviously know. Just repeat the ones you don't know. This saves time and helps you organize your endgame as the test gets closer.

• Write comparitive questions. They are a more efficient use of mental space because they encourage you to form connections rather than just memorize more facts. A comparitive question, like "Does acetylcholine act faster or slower than serotonin?" requires you to know three things, while the two questions "Does acetylcholine act fast or slow" and "Does serotonin act quickly or slowly?" requires you to remember a total of four things, two of which, the rates of action, are actually quite vague standing on their own. Acetylcholine is quick compared to what?

Medical school lectures can be fairly disorienting at times. A lecture may start as a broad overview of a system, and suddenly you find yourself trying to catch up because the lecturer is now talking about the second, no the third of three very important domains of a particular isoform of a particular membrane receptor found only in the first four inches of the duodonum. This is a consequence of the trophy model of presentation. There's an introduction, pillars of the discussion, and the conclusion. The pillars of the lecture, the tenents, the issues, the parts, whatever you want to call them, are logically equal, but must be addressed sequentially. As soon as the introduction is done, wham, you're in the details. Such is the limit of human intellect. Knowing, thankfully, goes a long way toward coping with it. This trophy model is taken to a bit of an extreme by some medical school lecturers because medical school lecturers don't usually lecture an entire course. They lecture anywhere from one lecture to half the class, usually between two and ten lectures. A new lecturer will typically start big and drill down to their area of expertise. So if you have three lectures from a physiologist who specializes in gut endocrinology, expect the first twenty to thirty minutes on the first day to be a general overview of the entire gastrointestinal system. While this is exceptionally repetitive, particularly if the last two lectures were on gut motility, the lecturer sees this as a very quick overview of terribly important material. Regardless, that's an issue to take up with the course coordinator. What you need to do is not start daydreaming about your hot date last night, foreign policy, your navel, or whatever it is you day dream about, and keep your Spidy-sense alert for that first pillar, the first details of the discussion.

Fat Doctor is hosting Grand Rounds, the weekly round-up of the best in the medical blogs. Volume 2, Number 30. Man, I didn't even know most of these blogs existed. And they're all better than mine....

MSNBC has probably provided the single most valuable file currently found on the internet: the New Orleans mayoral debate. Full length. Check out.

From the Times-Picayune: Charity to open interim trauma center

While this is certainly a sign of life, it is still disordered. My wife originally worked at the Elmwood facility's rehabilitation clinic. It's about fifteen or twenty minutes drive from downtown and nowhere near to be equiped as the long-term trauma service. There isn't enough parking and the facilities don't approach the capacity necessary to support the specialists a Level One Trauma Center has. As I recall it's a brick building about four stories tall and each floor is maybe the size of two or three three-bedroom ranch houses, so maybe 20,000 square feet. They don't even have the space for the imaging machines. If strokes and broken bones don't qualify, then this is surely not an emergency department. This is no joke trauma only.

The Elmwood site will not be the new Charity emergency department, Fontenot said, cautioning that the public should not consider it an option for routine injuries. The trauma center takes only seriously injured patients such as those with multiple fractures, gunshot wounds or heavy internal bleeding.

People with lesser trauma such as chest pain, strokes, broken limbs, cuts and other health concerns will still be directed to other local hospitals or Charity's temporary clinic at the former Lord & Taylor department store in the New Orleans Centre at 1400 Poydras St., Fontenot said.

Some really excellent public health resources are provided by those involved in indigent healthcare. I'm working on a project and the common thread is indigent healthcare, so I tag my internet sources indigent in del.icio.us. I thought I would really get some good ideas by looking at what sites all the other del.icio.us users in the world had labelled indigent. 36 links. How about homeless health? 69 links. How about charity? 2696 links; most of which have to do with soliciting money from rich people for low-rate-of-return projects like middle-class people hand-knitting scarves and giving them to poor people. Hey, I'm all for hand-knit scarves keeping people warm in the winter, but I'm thinking there are cheaper ways to get more scarves to more people.

All in all, I'm pretty savvy at literature review, and it's fairly obvious that not a lot of people think about taking care of the poor, but the ones that do think about it really hard. Probably some of the finest people in the world do this work. I'd say 94% of involvement is skin deep. The other 6% work themselves to the bone doing great work.

Here's the final report of the Bring New Orleans Back commission's Education Committee, their presentation to the commission, and, most recently, the testimony of Dr Scott Cowen, President of Tulane University, and chair of the BNOB Education Committee to the House of Representatives Committee on Education and the Workforce.

Here's the site for the Louisiana Department of Education and the New Orleans Public Schools. Here are some downloadable statistics on Louisiana public schools.