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Complex Systems: Introduction

Russ Abbott

Sr. Engr. Spec.

Rotn to CCAE

310-336-1398

Russ.Abbott@Aero.org

1998-2007. The Aerospace Corporation. All Rights Reserved.

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A fable

• There was once a state in India that had too many snakes.

• To solve the problem the government instituted an incentive-based program to encourage its citizens to kill snakes.

• It created the No Snake Left Alive program. – Anyone who brought a dead snake into a field office of the Dead

Snake Control Agency (DSCA) would be paid a generous Dead Snake Bounty (DSB).

• A year later the DSB budget was exhausted. DSCA had paid for a significant number of dead snakes.

• But there was no noticeable reduction in the number of snakes plaguing the citizens of the state.

• What went wrong?

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The DSCA mechanism

Submit a dead snake.

DSCA

Receive money.

Dead snakeverifier

Receive dead snake certificate. Submit

certificate to DSCA.

What would you do if this mechanism were available

in your world?

Start a snake farm.

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Inside DSCA: how does the DSCA work?

repeat foreverRead the next input;if (is-a-proper-DeadSnakeCert(input)then Dispense-money;

end

function is-a-proper-DeadSnakeCert(x)if (is-on-form-6942.4ax-rev-1(x) and all-fields-are-filled-in(x) and …) then return true;else return false;

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Moral: unintended consequences

• The preceding is an example of what is sometimes called an unintended consequence.

• It represents an entire category of (unintended and unexpected) phenomena in which

– a mechanism is installed in an environment but then

– the mechanism is used/exploited in unanticipated ways.

• Once a mechanism is installed in the environment, it will be used for whatever purposes users can think to make of it …

• which may not be the purposes for which it was originally intended.

The first lesson of complex systems thinking is that one must always be aware of the relationship between entities and their environments.

The first lesson of complex systems thinking is that one must always be aware of the relationship between entities and their environments.

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Locomotion in E. coli

• [E. coli] movements consist of short straight runs, each lasting a second or less, punctuated by briefer episodes of random tumbling: each tumble reorients the cell and sets it off in a new direction.

• Cells of E. coli are propelled by their flagella, four to ten slender filaments that project from random sites on the cell’s surface. … Despite their appearance and name (from the Greek for whip), flagella do not lash; they rotate quite rigidly, not unlike a ship’s propeller. …

• A cell … can rotate [its] flagellum either clockwise or counter-clockwise. Runs and tumbles correspond to opposite senses of rotation.

– When the flagella turn counter-clockwise [as seen from behind] the individual filaments coalesce into a helical bundle that rotates as a unit and thrusts the cell forward in a smooth straight run. …

– Frequently and randomly the sense of the rotation is abruptly reversed, the flagellar bundle flies apart and the cell tumbles until the motor reverses once again.

Harold, Franklyn M. (2001) The Way of the Cell: Molecules, Organisms, and the Order of Life, Oxford University Press.

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Locomotion in E. coli

Shana Topp and Justin P. Gallivan,“Guiding Bacteria with Small Molecules and RNA,” J. Amer. Chem. Soc. May 2007.http://pubs.acs.org/cgi-bin/sample.cgi/jacsat/2007/129/i21/pdf/ja0692480.pdf

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Mechanism, function, and purpose in E. coli

• Cells [which happen to be] moving up the gradient of an attractant … tumble less frequently than cells wandering in a homogeneous medium: while cells moving away from the source are more likely to tumble. In consequence, the cell takes longer runs toward the source and shorter ones away.

• How can a cell “know” whether it is traveling up the gradient or down? It measures the attractant concentration at the present instant and “compares” it with that a few milliseconds ago.

• E. coli can respond within a millisecond to local changes in concentration, and under optimal conditions readily detects a gradient as shallow as one part in a thousand over the length of a cell.

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Mechanism, function, and purpose

• Mechanism: The results of physical processes within an entity.

– E.g., the chemical reactions built into E.coli that result in its flagella movements.

• Function: The effect on the environment and the relationship between an entity and its environment as a result of the mechanisms.

– E.g., E. coli moves about. In particular, it moves up nutrient gradients.

• Purpose: The consequence for the entity of the change in its environment or its relationship with its environment.

– E.g., E. coli is better able to feed, which is necessary for self-persistence.

Image from Wikipedia Commons: http://commons.wikimedia.org/wiki/Image:Socrates_Louvre.jpg

Socrates

Compare to Measures of Performance, Effectiveness, and UtilityCompare to Measures of Performance, Effectiveness, and Utility

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How to drive a bacterium

Shana Topp and Justin P. Gallivan“Guiding Bacteria with Small Molecules and RNA” J. Amer. Chem. Soc., May 2007.http://pubs.acs.org/cgi-bin/sample.cgi/jacsat/2007/129/i21/pdf/ja0692480.pdf

Two ways:• Fool with its sensing equipment• Fool with its motor control.

The unintended consequence of being a bacterium is the potential for this sort of manipulation.

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• NetLogo (http://ccl.northwestern.edu/netlogo/) describes itself as “a cross-platform multi-agent programmable modeling environment … for simulating natural and social phenomena.”

• It is produced by the Center for Connected Learning and Computer-Based Modeling at Northwestern University.

• It is implemented in Java.

• Version 4.0 was released September 2007.

• It’s free to download, but it’s not open source.

• It produces executable models that run both as applications and as applets.

• It has a large library of models, which also run as both applications and applets.

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Learning Objectives

1. Learning Objective 1 (What it is 1)

2. Learning Objective 2 (What it is 2)

3. Learning Objective n (What it is 3)

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Outline of PresentationLearning Duration MTSObjective (min)

• Topic 1 LO 1 nn min TBD– Sub topic 1.1

– Sub topic 1.2

• Topic 2 LO 2 n.nn hr TBD– Sub topic 2.1

– Sub topic 2.2

• Topic 3 LO n nn min TBD

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Session Materials(This the material body)

• Instructor’s charts

• Items the instructor would like to use:– “Show and Tell” items like hardware– Video tapes– Case studies– Relevant recent news items– Quizzes– Group work, problem solving– Instructor led exercises– Etc..

• PowerPoint Notes Page -- mandatory– Used to capture acronyms – always do this!– References– Speaker's notes (optional)

• Think about the density of information given the learning objectives and time you have for the session

– Ensure you meet the learning objectives– You don’t need to tell everything you know

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Session Material(Illustrations)

Provide illustration of the system. Use one that isn’t proprietary. Simply, redraw, change, to make one without copyright issues.

We’d like material that is free of copyright or proprietary issues.Use Microsoft clip art or Aerospace repository of space illustrations (See

the Corporate Communication web site)

As a last resort, mark the diagram if the information came from somewhere else. Determine if that organization would allow us to use the diagram with their permission for a

course.

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Key Considerations

• These considerations may be:– Organizational – remember to involve x, y, z organizations

– System level – interfaces and trade space

– Challenge oriented – risk, failures

– Lessons learned, best practices, conventional wisdom, etc.

– Others

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Final Briefed Slide(Choose one of the styles below)

• This chart can be a summary, wrap-up, way forward or conclusions chart

• Summary of main learning points – Almost the inverse of the learning objectives chart

• Wrap-up– Gives an overview of what was covered

• Way-Forward– Useful for briefings showing plans

• Conclusions– Useful for sessions that derive qualitative or quantitative solutions

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Reference Material(Not briefed, but pointed to in the session)

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Tools

• Identify Aerospace tools or other tools essential to do the work.

• Identify organizations or POCs as you think make sense

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Session References

• List key document and web references that would help course participants dig deeper into the topic

– Try to use Aerospace material (TOR, ATM, Crosslink, etc.)

– Symposium papers

• One page is usually sufficient

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Session Resources

• List resources that can help participants understand or apply the work to their problem set

– Aerospace organizations

– Professional societies

– Customer groups

• Resources may be organizations, tools, facilities, people and or other courses

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Case Study Material(Optional – based on session

and course design)

• If Case Studies are useful to illustrate points they can be added as additional briefing material or for student use after the course

• For inclusion in the session, various case studies may be added to accommodate various instructors (instructor 1 knows case study 1, not 2; instructor 2 knows case study 2, not 1)

• For inclusion for student use they should stand on their own

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Student Reinforcement (Optional – based on session

and course design)

• This is used to reinforce key learning points

• It may be part of the session materials and used by the instructor or left as an exercise for the students to complete

• Examples include:– Quiz

– Matching

– Fill in the blank

– Multiple choice

– Essay