Saturday, July 4, 2009

Canon SD1100IS Digital Macro and Macro Mode Exploring

I'd just been learning the controls of our new Canon SD 1100 IS when I discovered CHDK, the Canon Hackers Development Kit.

This firmware hack liberates the Canon Powershots, enabling more features. One of those features is the ability to use a flash with digital macro. I am just beginning to explore.

First, two photos of the swimming sea anemone Boloceroides sp. outside the World Resort on Saipan.
The first is to show just how small this object is.

The second is taken hand held using digital macro mode and a flash, though in truth I cannot remember the exact camera settings.

A third photo was made with straight Macro Mode, handheld, at a low tide, without a camera housing. Star sand is something of a curiosity and many of my students have told me they have heard of Star Sand on Tinian.
Fewer realize that it is also found---and indeed even a predominant member of the reef flat community---on Saipan as well. At certain beaches, over 90% of the sand of the beach is made of these shells. Shells of what? An amoeba! Who'd've thought he's see an amoeba?!

This amoeba is a foraminiferan, a shell forming amoeba, and furthermore is a "Large Coral Reef Foraminiferan". Large Coral Reef forams (as they are called in short) have symbiotic plant cells living inside them. Many of them have Zooxanthellae, like corals do, photosynthesizing Dinoflagellates that give extra Carbon (food, sugar) to the host. Others, like this Baculogypsina sphaerulata, have symbiotic naked diatoms that fill the same role.

Want to see what's inside one of these stars? Here's a shot taken for a student's science fair project, of a decalicified Baculogypsina sphaerulata. This shot was taken with the same Canon Powershot "point and shoot," held by hand up to the eyepiece of a microscope. The in-scope magification was 200 power.

Saturday, May 30, 2009

Radical Lexicon: "Force the Thunk"

"Force the Thunk": I have seen this term several times on the org-mode mailing list. Here is are a few snippets from the Jargon List (hacker's dictionary, installable with apt-get on Ubuntu GNU/Linux installations). These are definitions for "thunk", with a hiistorical note at the end. I must preface these: I have no idea what this is all about. I can code a little simple lisp, but this involves, I think, run time composition of code, something list is known for. (Or NOT.) I am intrigued, and I hope to figure out how this works.

1. [obs.]"A piece of coding which provides an address:", according to P. Z. Ingerman, who invented thunks in 1961 as a way of binding actual parameters to their formal definitions in Algol-60 procedure calls. If a procedure is called with an expression in the place of a formal parameter, the compiler generates a thunk which computes the expression and leaves the address of the result in some standard location.

2. Later generalized into: an expression, frozen together with its environment, for later evaluation if and when needed (similar to what in techspeak is called a closure). The process of unfreezing these thunks is called forcing.

5. A person or activity scheduled in a thunklike manner. "It occurred to me the other day that I am rather accurately modeled by a thunk --I frequently need to be forced to completion.:" -- paraphrased from a {plan file}.

Historical note: There are a couple of onomatopoeic myths circulating about the origin of this term. The most common is that it is the sound made by data hitting the stack; another holds that the sound is that of the data hitting an accumulator. Yet another suggests that it is the sound of the expression being unfrozen at argument-evaluation time. In fact, according to the inventors, it was coined after they realized (in the wee hours after hours of discussion) that the type of an argument in Algol-60 could be figured out in advance with a little compile-time thought, simplifying the evaluation machinery. In other words, it had `already been thought of'; thus it was christened a thunk, which is "the past tense of `think' at two in the morning".

Saturday, April 25, 2009

Running (and walking) without shoes

An article , linked by addresses the need (or NOT) for running shoes. I am interested, as I was into the habit of using no shoes at all, in Chuuk. I scorched my feet pretty well on a midafternoon, walking up a highway in Kona Hawaii from the City of Refuge to Painted Church. After that, it was quite easy for me to walk barefoot anywhere. Gravel. Reef platforms (very difficult to do otherwise). I gradually built up thick soles on my feet.

In Chuuk, on the island of Tol, I walked daily to and from work, between Wonip Village and Foson, where I worked, almost always without shoes. Since leaving Chuuk some 14 years ago, I have probably lost a good amount of my callouses, but I can still walk in many situations without shoes. I was able to walk the rocky pathway over a mountain saddle after dark, on a moonless night, by feel. I wonder how I did that, even now. With shoes, I think it would be impossible.

This article mentions that the Stanford running team decided to train barefoot. Apparently the use of the most technologically advanced shoes caused most injuries.

In my case, I earlier had heel spurs, so I now use air-nikes. "Money won't change you, but time will take you out."

Saturday, March 14, 2009