Bushtits are small birds common in shrubby and woodland habitats. They are a year round resident of the western United States, and do not seem to mind residential areas. Its high pitch twittering contact call is first heard followed by the appearance of a flock ranging up to fifty birds. Members of the group constantly make contact calls to each other that can be described as a short “tsit”.

They typically swoop into an area en mass, bustle around noisily while eating and socializing, and then depart for more insect rich patches of greenery. They glean the vegetation for insects often hanging upside down in their search, gradually moving through the area.

Bushtits build elaborate pendulous nests made up of soft plant material, cobwebs, and man made items like threads and string. They are one of the first birds described to have helpers at the nest, a term used in behavioural ecology and evolutionary biology to describe a social structure in which juveniles and sexually mature adolescents, of either one or both sexes, remain in association with their parents and help them raise subsequent broods or litters.

The birds successfully petitioned for a change-of name when it was brought to their attention that the word “common” had unsavory connotations, a circumstance made particularly agregious by the fact they already had a reputation as noisy little tits. Despite its name, the Bushtit is not a well-endowed member of a prominent American political family.

Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters. Spiral galaxies make up approximately 60% of galaxies in the local Universe. They are mostly found in low-density regions and are rare in the centers of galaxy clusters.

Spiral galaxies are named for the spiral structures that extend from the center into the disk. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disk because of the hot, massive stars that inhabit them. Spiral arms contain a great many young, blue stars, which make the arms so remarkable. Roughly half of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge, at the ends of which the spiral arms begin.

Our own Milky Way has recently been confirmed to be a barred spiral, although the bar itself is difficult to observe from our position within the Galactic disk. The most convincing evidence for its existence comes from a recent survey, performed by the Spitzer Space Telescope, of stars in the Galactic center.

Bertil Lindblad proposed that the arms represent regions of enhanced density waves that rotate more slowly than the galaxy’s stars and gas. As gas enters a density wave, it gets squeezed and makes new stars, some of which are short-lived blue stars that light the arms.

This idea was developed into density wave theory by C. C. Lin and Frank Shu in 1964. They suggested that the spiral arms were manifestations of spiral density waves, attempting to explain the large-scale structure of spirals in terms of a small-amplitude wave propagating with fixed angular velocity, that revolves around the galaxy at a speed different from that of the galaxy’s gas and stars.

Mooncrete is an idea first proposed by Larry A. Beyer of the University of Pittsburgh in 1985. It is a hypothetical aggregate building material, similar to concrete formed from lunar regolith, that could cut the construction costs of building on the moon.

Basic ingredients for mooncrete would be the same as those for terrestrial concrete: aggregate, water, and cement. In the case of mooncrete, the aggregate would be lunar regolith. The cement would be manufactured by beneficiating lunar rock that had a high calcium content. Water would either be supplied from the moon, or by combining oxygen with hydrogen produced from lunar soil.

The casting of mooncrete would require a pressurized environment, because attempting to cast in a vacuum would simply result in the water, required for the chemical reaction that forms the curing process, evaporating, and the mooncrete failing to harden. Two solutions to this problem have been proposed: premixing the aggregate and the cement and then using a steam injection process to add the water, or the use of a pressurized concrete fabrication plant that produces pre-cast concrete blocks.

Mooncrete shares the same lack of tensile strength as terrestrial concrete. One suggested lunar equivalent tensioning material for creating pre-stressed concrete is lunar glass, also formed from regolith, much as fibreglass is already sometimes used as a terrestrial concrete reinforcement material. Another tensioning material, suggested by David Bennett, is Kevlar, imported from Earth, which would be cheaper, in terms of mass, to import from Earth than conventional steel.

The yellow jacket is a common name in North America for predatory wasps of the generaVespula. Members of these genera are known simply as wasps in other English-speaking countries. Most of these are black-and-yellow, while others may have the abdomen background color red instead of black. They can be identified by their distinctive markings, small size, their occurrence only in colonies, and a characteristic, rapid, side to side flight pattern prior to landing.

Nests are built in trees, shrubs, or in protected places such as inside human-made structures, attics, hollow walls or flooring, in sheds, under porches and eaves of houses, or in soil cavities and mouse burrows. Nests are made from wood fiber chewed into a paper-like pulp.

In 1975, the German yellowjacket first appeared in Ohio and has now become the dominant species over the Eastern Yellow Jacket. It is bold and aggressive, and if provoked, it can sting repeatedly and painfully. The German yellowjacket builds its nests in cavities with the peak worker population between 1,000 and 3,000 individuals during May to August, each colony producing several thousand new reproductives after this point, through November.

The Eastern Yellow Jacket builds its nests underground. Nests are built entirely of wood fiber and are completely enclosed except for a small entrance at the bottom. The color of the paper is highly dependent on the source of the wood fibers used. The nests contain multiple, horizontal tiers of combs within. In the Southeastern United States, where southern yellowjacket nests may persist through the winter, colony sizes of this species may reach 100,000 adult wasps.

The yellowjacket’s most visible place in American culture is as the mascot of the Georgia Institute of Technology, Montana State University Billings, University of Rochester and Berkeley High School in California. In Columbus, Ohio, the Columbus Blue Jackets formerly used a logo featuring a “blue jacket” insect, based on the yellowjacket. This fictional “blue jacket” resembles a yellowjacket wearing a blue Civil War uniform.

A strange loop arises when, by moving up or down through a hierarchical system, one finds oneself back where one started. It is a hierarchy of levels, each of which is linked to at least one other by some type of relationship. A strange loop hierarchy, however, is “tangled” (Hofstadter refers to this a “heterarchy”), in that there is no well defined highest or lowest level; moving through the levels one eventually returns to the starting point, i.e., the original level. Examples of strange loops that Hofstadter offers include: many of the works of M. C. Escher, the information flow network between DNA and enzymes through protein synthesis and DNA replication, and self-referential Gödelian statements in formal systems.

In I Am a Strange Loop, Hofstadter defines strange loops as follows:

“ What I mean by “strange loop” is — here goes a first stab, anyway — not a physical circuit but an abstract loop in which, in the series of stages that constitute the cycling-around, there is a shift from one level of abstraction (or structure) to another, which feels like an upwards movement in a hierarchy, and yet somehow the successive “upward” shifts turn out to give rise to a closed cycle. That is, despite one’s sense of departing ever further from one’s origin, one winds up, to one’s shock, exactly where one had started out. In short, a strange loop is a paradoxical level-crossing feedback loop.

Hofstadter claims a similar “flipping around of causality” happens in minds possessing self-consciousness. The mind perceives itself as the cause of certain feelings, (“I” am the source of my desires), while scientifically, feelings and desires are strictly caused by the interactions of neurons, and ultimately, the probabilistic laws of quantum mechanics.

A pouf is a style of hair which came about in 18th Century France. First used by Marie Antoinette, it became popular among the wealthy women of France. 

Developed in conjunction with hairdresser Monsieur Leonard, the pouf consisted of a scaffolding made from wire, cloth, gauze, horsehair and fake hair, with the wearer’s own hair teased high off the forehead. On top of this huge confection of hair was a display of feathers, flowers, vegetables or other objects designed to express a topical message. For example, Marie-Antoinette commissioned a huge pouf showcasing an intricate hairdo displaying a French frigate that won a key victory against the British in June 1778.

The pouf was adapted by woman of class based on current events. For example, during the American Revolution poufs included model ships to show support for the Americans and their war against the British. During the French Revolution women took the pouf hairstyle and turned it to their favours to support the revolution. The pouf became popular among many women across Europe and the United Kingdom.

It was not an easy hairstyle to adopt. The underlying contraption was heavy and difficult to sleep in. Marie Antoinette would have had to wrap her head in a huge bandage-like wrap and sleep semi-upright. And since grease was used to glue the hair in place, the pouf was impossible to wash and fostered breeding grounds for vermin. But this did not stop other women from emulating the French Queen of Fashion. One lady of the court declared “I shall never again wear anything but vegetables! It looks so simple, and is so much more natural than flowers!”

Unfortunately, the pouf also corresponded to a time of bad harvests and harsh winters in France. Appearing at the opera, theatre and parties in her wedding cake-like coiffure, Marie Antoinette flouted her lifestyle in the face of a starving nation. It was particularly horrifying to hungry peasants that the whiteness of the pouf coiffure came from flour. Popular opinion turned from admiration to distaste and Marie Antoinette’s willingness to consider more serious matters was questioned.

Maize, primarily known as corn in North America, is a cereal grain domesticated in Mesoamerica and subsequently spread throughout the American continents. After European contact with the Americas in the late 15th and early 16th centuries, maize spread to the rest of the world.

It is the most widely grown crop in the Americas, with 332 million tons grown annually in the United States alone. Hybrid maize is preferred by farmers over conventional varieties. While some maize varieties grow up to 23 feet tall, most commercially grown maize has been bred for a standardized height of 8 feet. Sweet corn is usually shorter than field-corn varieties.

Maize stems resemble bamboo canes and the internodes can reach 12 inches. It has a very distinct growth form. The lower leaves are like broad flags and the stems are erect, casting off flag-leaves at every node. Under these leaves, close to the stem, grow the ears. They grow about 3 milimetres a day.

The ears are female flowers, tightly covered over by several layers of leaves, and so closed-in by them to the stem that they do not show themselves easily until the emergence of the pale yellow silks from the leaf whorl at the end of the ear. The silks are elongated stigmas that look like tufts of hair, at first green, and later red or yellow. Certain varieties of maize have been bred to produce many additional developed ears, and these are the source of the baby corn that is used as a vegetable in Asian cuisine.

The apex of the stem ends in the tassel, an inflorescence of male flowers. Each silk may become pollinated to produce one kernel of corn. Young ears can be consumed raw, with the cob and silk, but as the plant matures the cob becomes tougher and the silk dries to inedibility. By the end of the growing season, the kernels dry out and become difficult to chew without cooking them tender first in boiling water. Modern farming techniques in developed countries usually rely on dense planting, which produces on average only about 1 ear per stalk because it stresses the plants.

The kernel of corn has a pericarp of the fruit fused with the seed coat, typical of the grasses. It is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows round a white pithy substance, which forms the ear. An ear contains from 200 to 400 kernels. When ground into flour, maize yields more flour, with much less bran, than wheat does. However, it lacks the protein gluten of wheat and, therefore, makes baked goods with poor rising capability and coherence.

Maize contains lipid transfer protein, an undigestable protein which survives cooking. This protein has been linked to a rare and understudied allergy to maize in humans. The allergic reaction can cause skin rash, swelling or itching of mucus membranes, diarrhoea, vomiting, asthma and, in severe cases, anaphylactic shock. It has been noted that those with corn allergy almost always have peach allergy as well. It is unclear how common this allergy is in the general populace.

A volcano is an opening, or rupture, in a planet’s surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. The Ancient Romans called volcanoes Vulcano, after Vulcan, their fire god.

Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart. The Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth’s crust, such as in the African Rift Valley, the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.

Volcanoes can be caused by mantle plumes. These so-called hotspots, for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons.

The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit. This describes just one of many types of volcano, and the features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater, whereas others present landscape features such as massive plateaus. Vents that issue volcanic lava and gases can be located anywhere on a landform.

Other types of volcano include cryovolcanoes or ice volcanoes, particularly on some moons of Jupiter, Saturn and Neptune. Mud volcanoes are formations often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes, except when a mud volcano is actually a vent of an igneous volcano.

Many ancient accounts ascribe volcanic eruptions to supernatural causes, such as the actions of gods or demigods. To the ancient Greeks, volcanoes’ capricious power could only be explained as acts of the gods, while the 16th German astronomer Johannes Kepler believed they were ducts for the Earth’s tears.

Various explanations were proposed for volcano behavior before the modern understanding of the Earth’s mantle structure as a semisolid material was developed. For decades after awareness that compression and radioactive materials may be heat sources, their contributions were specifically discounted. Volcanic action was often attributed to chemical reactions and a thin layer of molten rock near the surface.