January 6 COVER The porous deposit of candle soot can be used as a template for a super oil- and water-repellent coating. The soot is coated with a thin silica shell to form a replica and is then removed by calcination. The silica is treated with a fluorosilane, yielding a transparent, stable coating. This cheap and easily upscalable approach may inspire the design of anti-fingerprint coatings, which are desirable for touchscreens or glasses. See page 67. Photo illustration: Bricelyn Strauch and Yana Hammond/Science; candle image: Fotosearch

January 13 COVER A young wandering albatross (Diomedea exulans) glides smoothly over the Southern Ocean swell during a calm day. Albatrosses take advantage of ocean winds to travel more efficiently. Recent changes in Southern Ocean wind conditions have allowed wandering albatrosses to travel more rapidly and shift their foraging range southward, with positive influences on reproduction and potential contributions to albatross conservation. See page 211. Photo: Paul Tixier

February 3 COVER Computer illustration of streams of matter delineating the network of cosmic voids, each tens of millions of light years across. Matter accumulates where the voids meet, forming a cosmic web of walls, filaments, and clusters of galaxies. This illustration was awarded first place in the informational graphics category in the 2011 Science/NSF International Science & Engineering Visualization Challenge. The winning entries are featured in a special section starting on page 525 and at www.sciencemag.org/site/special/vis2011/. Image: Miguel A. Aragon Calvo, Julieta Aguilera, Mark Subbarao

March 16 COVER False-colored scanning electron micrograph of ~8-micrometer-tall germanium crystals, separated by finite gaps, grown onto silicon pillars. In structures like this one, wafer bowing and layer cracking are absent, allowing single-crystal integration of different materials onto a silicon substrate, which serves as a platform for many applications, such as multiple-junction solar cells, x-ray and particle detectors, or power electronic devices. See page 1330. Image: Claudiu V. Falub, Laboratory for Solid State Physics, Swiss Federal Institute of Technology (ETH-Zürich)

April 6 COVER Polarized light micrograph of a thin section of gypsum crystals (CaSO4•2H2O). Vertical field of view ~4 millimeters. This natural and industrial mineral unexpectedly crystallizes from solution at room temperature upon a transition through a precursor, nanocrystalline bassanite (CaSO4•0.5H2O), a usually high-temperature phase. A detailed understanding of this crystallization route could lead to a new strategy to control gypsum scale and may open an alternative route for the production of “plaster of Paris” (bassanite).

April 13 COVER A series of spheres with two-dimensional patterns generated by computer simulation shows that Turing’s reaction-diffusion model may be the basis for skin patterning in animals. A modulation of one parameter value in a reaction-diffusion–based model causes the pattern to change gradually from spots to labyrinths, with the range encompassing the diversity of patterns seen on animal skin. See page 171 and http://scim.ag/comp_bio. Image: Seita Miyazawa, Osaka University

April 20 COVER A young polar bear (Ursus maritimus) on a piece of ice that is drifting in the Barents Sea, northeast of Svalbard, Norway. Polar bears depend on sea ice as a platform for hunting seals, but current melting and retreat of sea ice is increasingly forcing them onto land. A recent study has found polar bears to be evolutionarily older and genetically more distinct than was previously thought.

April 27 COVER Overlayed scanning tunneling and atomic force microscopy images of a single atom (width 1.3 nanometers): tunneling current (gray veil) and force (colored surface) between a tungsten atom and a carbon monoxide molecule. The force shows a strong angular dependence and is attractive (blue minimum) in one direction and repulsive (dark red crescent) in others. The angular dependence of single chemical bonds determines the shape of molecules and crystals.

May 18 COVER We are all too familiar with human conflict, such as this bombing on 13 August 2006 in Beirut, Lebanon, by the Israel Defense Forces. In the special section on Human Conflict (see page 818), we examine the origins of conflict, trace its path through history, and consider its modern manifestations. We also analyze our innate ability to foster peace and look at societies that eschew war. This cover was chosen for visual imagery and not for any political message or endorsement. Image: Sang-Hoon KISH Kim/Sipa Press/Newscom

June 1 COVER Three-dimensional computer models such as this one help researchers explore the mechanisms behind core-collapse supernovae, the violent death of short-lived massive stars. In the image, tubes represent paths of gas falling into a supernova, deflected by an accretion shockwave (horizontal width of 600 km); colors represent different velocities. The question of how stars explode is one of the “Mysteries of Astronomy” described in a special News package beginning on page 1090. Visualization: Hongfeng Yu and Kwan-Liu Ma, University of California-Davis and the SciDAC Institute for Ultra-Scale Visualization; Simulation: John Blondin, North Carolina State University

June 29 COVER Wet bark of a Pacific yew tree (Taxus brevifolia) in Union, Washington, USA (vertical dimension ~15 centimeters). Wild Pacific yew thrives in the damp coastal forests of northwestern North America, with thin bark ranging in color from rose to auburn. The anticancer agent pactitaxel was originally derived from yew trees. Such complex and useful compounds are just one of the many outputs from plant metabolic networks, as analyzed in the special issue beginning on page 1657. Photo: Don Paulson, www.donpaulson.com

July 6 COVER Structure of the Wnt signaling molecule (red) in complex with the Frizzled ligand-binding domain (yellow), schematically depicted as connected to the cell surface. A key feature of this structure is the visualization of a lipid group (blue) on Wnt directly engaging Frizzled. The Wnt/Frizzled mode of binding paves the way for the design of Wnt-based therapeutics. See page 59. Image produced by Eric Smith and Chris Garcia

August 3 COVER Illustration of the black hole in Cygnus X-1, a binary star system 6000 light-years away. A disk of stellar material feeds this black hole, which is 15 times as massive as the Sun but less than 60 kilometers across. As it falls toward the black hole, some of the material gets expelled in two opposite jets. A section highlighting recent research on black holes begins on page 535. For the story behind the cover, go to http://scim.ag/cov6094. Image: NASA/Chandra X-ray Center/M. Weiss

August 10 COVER Recycling aluminum cans (shown here in bales at a facility in Philadelphia, PA) is just one of the many approaches directed toward doing something productive with the world’s ever-expanding stream of waste. In the special section Working with Waste (page 662), we survey multifaceted efforts to tackle this global challenge. For the story behind the cover, go to http://scim.ag/cov6095. Photo: Huguette Roe, www.hroephoto.com

August 17 COVER Male rhinoceros beetles (Trypoxylus dichotomus) wield a huge forked horn on their heads. Sexual selection may favor the evolution of exaggerated trait sizes because the developmental mechanism responsible for increased growth also results in signal reliability. See page 860. Photo: Will Freihofer and Douglas Emlen

August 24 COVER Artist’s rendering of the airway epithelial cell surface in human lungs. The airway surface is lined by arrays of cylindrical cilia (shown as yellow projections) that are 7 micrometers long and 200 nanometers in diameter. The cilia and airway surface are covered by tethered biomacromolecules (shown as green hairs) that form dense, brushlike structures. These epithelial brushes protect the airways from infectious agents and ensure efficient flow of mucus from healthy lungs. See page 937. For the story behind the cover, go to http://scim.ag/cov6097. Image: Yan Liang (www.l2xy2.com), Li-Heng Cai, Michael Rubinstein

September 7 COVER Artist’s conception of the complex network of relationships between disease and the human genome. Hundreds of diseases and traits (represented by colored dots) have been mapped to specific chromosomal positions in the genome. Most disease-associated genetic variants fall outside of protein-coding genes, instead affecting the genome’s regulatory circuitry by modifying the DNA “switches” (some of which are depicted here as gray triangles, many others not shown) that control gene activity. See page 1190. Image: Rachael Ludwig and John Stamatoyannopoulos

October 5 COVER A solitary figure walks through a somber urban landscape. The permeating tone of sadness in this painting gives an impression of life with major depressive disorder, whereas the light punctuating the scene hints at hope. Because depression has become a serious problem in societies around the world, it is crucial to investigate the basic mechanisms underlying this disease and to develop effective prevention and therapies. See the special section beginning on page 67. For the story behind the cover, go to http://scim.ag/cov6103. Image: “Midnight Stroll” by Michael Bishop, http://mbishopart.artweb.com/

October 12 COVER False-colored scanning electron micrograph of a zebrafish (Danio rerio) embryo (~0.7 millimeters across) at a late stage of development. Biophysical studies of model organisms such as zebrafish reveal forces that organize tissue patterns and shape cell layers and physical features (segments, cavities, and folds). The special section beginning on page 209 presents work in which physicists and biologists collaborate to explain the physical mechanisms of animal development. Image: Dr. Richard Kessel/Visuals Unlimited, Inc.

October 19 COVER Optical vortices emitted by an array of silicon ring resonators. The helical phase fronts, indicated by spirals, denote photons with orbital angular momentum. Emission results from the embedded angular gratings that extract the light waves traveling around the ring. The small emitters (diameter: 8 micrometers) can be integrated on a large scale into photonic integrated circuits, enabling new applications in optical communications and sensing, quantum photonics, and lab-on-a-chip. See page 363. Image: Yue Zhang (ciel924@126.com), based on data from Xinlun Cai, Jiangbo Zhu, and Siyuan Yu

November 23 COVER The lower hemisphere of a fast-spinning Earth shown 2 hours after a giant impact. Colors denote the silicate mantles and iron cores of Earth and the impactor. The debris evolves into a Moon-forming disk composed primarily of material from Earth’s mantle, explaining the isotopic similarity between Earth and the Moon. In this model, the fast-spinning Earth is slowed by an orbital resonance between the Moon and the Sun. See pages 1040, 1047, and 1052. Image: Sarah T. Stewart

November 30 COVER Computer-generated models of three-dimensional nanostructures that were self-assembled from synthetic DNA strands called DNA bricks. A master collection defines a 1000-voxel “molecular canvas” with a 25-nanometer edge. By selecting subsets of bricks, Ke et al. constructed a panel of 102 distinct shapes with sophisticated surface features and intricate interior cavities and tunnels. These nanostructures may find applications ranging from biomedicine to nanoelectronics. See page 1177. Image: Yonggang Ke

December 7 COVER End-on view of the atomic model of the bacterial actinlike ParM protein double-helical filament, generated from an electron microscopic reconstruction. A bipolar spindle of antiparallel ParM filaments pushes plasmids to the cell poles, constituting the simplest known apparatus for the segregation of genetic information. The loops on the outside of the 8- to 9-nanometer-thick filaments are involved in spindle formation. See page 1334. Image: Jan Löwe