June 13, 2003

Small, cheap, motorized scooters

In my neighborhood there is a bit of a summer fad going on that involves young men (mostly) zooming about on inexpensive (~$400) motorized scooters. I would trace the evolution of these scooters back to the foot powered ones that kids zoom about on (the progression involved putting motors on the scooter with the rider standing, followed by the addition of, bigger wheels, seats and fenders).

Beyond curiosity and a bit of middle-age grumbling, an interesting set of thoughts was triggered when I wondered where one would get parts and repair for these things. The answer I came up with is that you probably don't. These machines are cheap enough so that if they last the better part of the summer they are purchased at the beginning of, then they become essentially disposable and rapid dissemination can come in the absence of any infrastructure other than distribution of the machines themselves (e.g. UPS).

The key to this set of ideas seems to be a confluence of inexpensive design and increase in reliability. At point where disposability crosses price in some utility space, the need for a supporting infrastructure beyond distribution and disposal goes away.

The Properties of a Good Consitution

Following The Economist:

A good constituion is short, simple and clear. It avoids attention to detail, but lays out a set of processes for making decisions and for giving attention to detail. The processes it lays out can be changed but not easily or without significant deliberations. A good constitution sets out the goals of the organization it guides and the means for achiveing those goals.

A constitution should avoit detail because it is likely to get much of it wrong. Constituions need to have long time scales in order to engender confidence that the governing framework is stable. Thus the details need to be handled at a "lower" level. It is a mistake to allow decision-making scales to become strongly linked. That is, details must be able to be adjusted as learning occurs without changing the constituion.

June 12, 2003

Bounded Rationality

A classical conceptualization of decision making is the following:

  1. A set of goals is identified

  2. All possible parhts to the goals are articulated

  3. The complete portfolio of costs & benefits for all paths is calculated

  4. The path or paths which maiximizes (optimizes) benefit is chosen

This is a rational frame, but it relys on / assumes complete information and large computational capacity. In all but the simplest cases, the completeness of this scheme makes it unimplementable.

In place of this optimizing scheme, James March and Herbert Simon suggest that a better model is the following:
  • Rather than optimal goals, satifactory conditions are set.

  • Familiar modes of action are tried first, without global cost / benefit analysis

  • To the extent that costs and benefits are considered, they are evaluated relative to local conditions using local knowledge

  • When a satisfactory state is achieved, action stops; there is no attempt to maximize utility, only to attains some acceptable level.

In this frame actions do not have complete information and different actors have different (and not necessarily consistent) information. Achieving a satifactory state can be accopmplished in two ways. First the activities and decisions that are undertaken can advance the system to a new and satisfactory state. Second, if progress toward a satisfactory conditions is too difficult or slow, the standards themselves may be adjusted to accept achievable states as satisfactory.

Innovation can be aded to this program by constraining when statisficing conditions can be changed and including exploratory behaviors in the portfolio of "familiar actions."

This sounds a lot like genetic algorithms - stand by while I explore that further.

Complex behaviors can be achieved without global knowledge at any single points if satificing levels, action programs and problems are parsed (broken into chunks) in the right way. Of course there is no prescription for how to find "the right way" and in a satisficing world, there are likely to be more than one. The details of the "complex behavior" will of course depend on which "right way" is found and operationalized.

June 11, 2003

Temperature Changes - part 1

This is the first installment of a series of posts where I plan to discuss the current state of the climate system. In these posts I will use publicly available data and make simple observations about this temperature history of our planet. In this installment I am going to look at the glacial cycles of the past 400,000 (400K) years.

The figure above shows a record of the temperature of the atmosphere in Antarctica over the last 400K years. These temperatures are calculated from measurements of the concentrations of certain gasses that become trapped in small bubbles in the ice as it is compacted. The measure of temperature is not absolute; it is a difference from some reference period. In this case the reference is the average temperature over a number of recent decades. Note that time is indicated in years before present.

In the figure there are 4 glacial cycles labeled G1 through G4. Each of those cycles is about 100K years long. G1 the most recent glacial cycle ended about 10,000 years ago. Each of the four complete cycles starts with a fairly rapid decrease in temperature to temperatures that are 2 - 8 degrees Celsius colder than today. The cold periods are glacial periods. One thing that is striking is that while the temperature remains "cold" during a glacial period, there are fairly large variations. Each of the glacial cycles ends very abruptly with a large increase in temperature from fairly cold to levels that are perhaps a couple of degrees warmer than today.

In each of the cycle there is a blue line and a red line. The blue line represents the average rate of temperature decrease for the 10K years following the peak temperature. Each blue line is labeled with a negative number that gives the rate of temperature decrease in degrees per year. The red line in each cycle is the average rate of temperature increase for the abrupt ending of the cycle. The red lines are labeled with positive numbers that give the rate of temperature increase in degrees per year.

Remember that the "e" indicates scientific notation thus 1e-3 is 0.003.

Note that each of the cycles G1-G4 ends with temperature increase rates that are very similar - roughly 1.1e-3 degrees per year. While not quite as similar, the rates of temperature decrease that signal the beginning of each the cycles is about the same; G1, G3, and G4 begin with rates of temperature decrease of about 3.5e-4. G2 begins with temperatures falling at about twice that rate. The changes in temperature that mark the end of a cycle are more than 10 times as rapid as those that start the period. So cycles G1-G4 have very similar temperature histories. They start with rapid cooling of (roughly the same rate), they show oscillations during the glacial period which lasts about 100K years and they end with very rapid increases in temperature.

The short blue line at the very right of the figure represents the average temperature change over the time since the end of the last full glacial cycle. That average shows that temperature has been decreasing, but at a very slow rate compared to the previous cycles (about 10 time slower). Agriculture was invented at the very beginning of this period of relatively stable, and warm, temperatures; and all of the subsequent major developments in human history have occurred in times of historically stable temperatures.

The main point in this figure is that compared to the last 400K years, the recent 10K years are anomalous. If the pattern of the cycles G1 - G4 had repeated again, we would now have temperatures that would be much colder than than we now have.

Exercise for the reader What have I glossed over in the preceding?

June 9, 2003

Monkey Pox

A number of Midwestern states have reported cases of monkey pox. Apparently these are the first cases of this disease to be reported in the western hemisphere. Fortunately, while monkey pox symptoms are similar to small pox, it is not as virulent and mortality in generally healthy populations is likely to be low.

I have written some on SARS and how it appears that that virus may have jumped from domestic animals to humans. The same appears to be true of monkey pox, but rather than pigs and chickens, the animals are Gambian rats and prairie dogs. The path appears to be from Gambian rat to prairie dog to human. Monkey pox makes the prairie dogs sick and can be fatal to those animals As reported by the AP it may be that most of the cases in the midwest can be traced back to a single exotic pet distributor in Chicago. That shop has been quarantined and many of its prairie dogs have been killed.

This brings to mind a number of thoughts. The first of which is "What in world are people thinking with respect to pets!?" Now I may be a bit curmudgeonly on this front, but I don't think that I am out of line thinking that it doesn't make a lot of sense to bring large African and Texan rodents together in close quarters and then to add a large primate to the mix.

Joel Cohen and his collegues figured out that huge decreases in Chagas disease could be achieved by having the livestock live outside and the humans live inside. While this seems obvious in the case of the rural Andes, it does not seem to be applied to suburban Chicago.

Two other things that come to mind are: 1) the seeming prevalence of disease that jumps from animals to humans; and 2) the global mixing of species. Quick surveys of the web suggest that monkey pox, here-to-fore, has been confined to central Africa. Now it has jumped directly to the metropolitan Midwest. There seems to be no question that the disease was transported by exotic pet traders from Africa to the US. I don't know whether to be amazed that our livestock controls have worked so well for so long or to be horrified at the thought of the geographically artificial inter-species mixing that is going on.

It is likely that this little outbreak will be controlled (provided people don't start turning their sick prairie dogs out into the wild where they can / will infect healthy indigenous populations). And it is in many ways a simple and relatively benign case of human foible and ecentricity. It does, none-the-less, illustrate the kind of thing that we need to manage as we go forward. In this case there are many regulations that control the flow of animals across borders and across ecological niches. That regulatory framework may need to be shored up, but it is one way to approach the problem.

But what happens when something slips through the regulatory net, as appears to have happened with monkey pox; or when the regulatory net is non-existent or inadequate as would be the case with SARS in Guang Dong? When that happens we need another set of mechanisms that are highly dynamic and that can react to a rapidly changing state of affairs. With disease it looks like the strategy is to isolate the disease and then eliminate it; this is the strategy behind quarantine. If a disease gets established in wild populations (as may be the case with SARS and is the fear regarding sick prairie dogs going into the wild) then isolation and eradication will not work and the strategy has to be one of controlling and limiting outbreaks. If we are lucky vaccines can be developed and human morbidity minimized.

Earth systems management is going to have to be able to deal with existing and emerging infectious diseases and the fact that these things will be moved around the globe in strange ways as a function of human weirdness.