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Biofilm Growth
Growth of a biofilm of the bacteria Bacillis subtilis over four days.
Bragg Peak
When energetic protons enter tissue, they release most of their energy as they come to rest. Damage to nearby organs and structures can be minimized.
A population of slime-mold cells forms an aggregate in response to a signaling molecule.
At the center of a cyclotron, a charged particle travels through a magnetic field that curves its path into a spiral and out of the cyclotron at a high speed.
DNA Helix Animation
The double helix.
Random Motion
Random motion of gas molecules—bottom up.
Rotational Entropy
Rotational entropy is related to the number of possible ways particles can be arranged in a structure. The greater the number, the greater the entropy.
Vibrational Entropy
There are different kinds of entropy. Vibrational entropy describes the number of ways that a structure can flex or vibrate without breaking.
Virus Self-Assembly
In some viruses the capsid appears to be completely self-assembled. Understanding capsid self-assembly could present new ways to fight disease.


Bacterial Photo
The left panel shows the projected image of students and professors who participated in the project, and the right panel shows the bacterial photo.
Rainbow images showing individual neurons fluorescing in different colors. By tracking the neurons through stacks of slices, we can follow each neuron's complex branching structure to create the treelike structures.
Darwin's Finches
The variation in Galapagos finches inspired Charles Darwin's thinking on evolution, but may evolve too fast for his theory.
A chicken egg. Is it alive or dead?
Gage, Phineas
In 1848, a steel rod shot through the left cheek the Phineas Gage and exited through the top of his head. Gage never lost consciousness and lived another 13 years.
As a glass cools, the viscosity increases so rapidly that the atoms get frozen in a disordered state.
Ruby-throated hummingbird
Polarized Light Through Corn Syrup
As polarized light passes through corn syrup, which is full of right-handed sugar molecules, its plane of polarization is rotated.
Rubik's Cube
A Rubik's Cube is a familiar example of a hierarchical distribution of states.
Shark Cartilage
Cartilage from the fin of the Mako shark.
Wake Vortex
Colored smoke marks the hydrodynamic flow around an aircraft, an emergent phenomenon.

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Binding Site Logo
This sequence logo is a compact way of displaying information contained in a piece of genetic material.
Complex Adaptive Behavior
A schematic view of what constitutes a complex adaptive system.
Computer Schematic
Schematic of a modern digital computer.
DNA Configurations
The DNA double helix, in three of its possible configurations.
Energy Landscape
Here, we see two possible paths across an energy landscape strewn with local minima.
The enzyme on the left has a much easier time reading DNA than the enzyme on the right due to structural details that are difficult to predict from first principles.
Fitness Landscape
Natural selection can be viewed as movement on a fitness landscape.
Frustrated Spin System
This simple system of three spins is frustrated, and has no clear ground state.
The structure of myoglobin (left) and the form it actually takes in space (right).
Natural Selection
Sewall Wright sketched the path different populations might take on the fitness landscape.
Prion Structures
Two possible conformations of a prion protein: on the left as a beta sheet; on the right as an alpha helix.
Protein Folding Funnel
A schematic of how minimizing the free energy of a molecule could lead to protein folding.
The circuit diagram (top), bacterial population (center), and plot of the dynamics (bottom) of the repressilator, an example of a simple synthetic biological network.
The chemical structure of RNA (left), and the form the folded molecule takes (right).
Molecules of life: RNA (left) and DNA (right).
Traveling Salesman Problem
An optimal travelling salesman problem (TSP) tour through Germany's 15 largest cities. It is the shortest among 43,589,145,600 possible tours visiting each city exactly once.
Turing Test
Player C is trying to determine which player—A or B—is a computer and which is a human.