Philosophy of mind is the branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body. The mind-body problem, or the relationship of the mind to the body, is commonly seen as the central issue in philosophy of mind, although there are other issues concerning the nature of the mind that do not involve its relation to the physical body.

Dualism and monism are the two major schools of thought that attempt to resolve the mind-body problem. Dualism is the position that mind and body are in some way separate from each other. It can be traced back to Plato, Aristotle, and the Samkhya and Yoga schools of Hindu philosophy, but it was most precisely formulated by René Descartes in the 17th century. Substance dualists argue that the mind is an independently existing substance, whereas Property dualists maintain that the mind is a group of independent properties that emerge from and cannot be reduced to the brain, but that it is not a distinct substance.

Many modern philosophers of mind adopt either a reductive or non-reductive physicalist position, maintaining in their different ways that the mind is not something separate from the body. These approaches have been particularly influential in the sciences, particularly in the fields of sociobiology, computer science, evolutionary psychology and the various neurosciences. Other philosophers, however, adopt a non-physicalist position which challenges the notion that the mind is a purely physical construct.

Reductive physicalists assert that all mental states and properties will eventually be explained by scientific accounts of physiological processes and states. Non-reductive physicalists argue that although the brain is all there is to the mind, the predicates and vocabulary used in mental descriptions and explanations are indispensable, and cannot be reduced to the language and lower-level explanations of physical science. Continued neuroscientific progress has helped to clarify some of these issues. However, they are far from having been resolved, and modern philosophers of mind continue to ask how the subjective qualities and the intentionality of mental states and properties can be explained in naturalistic terms.

Zydeco, from the French le zaricot or “snap beans” is a popular form of American folk music. It evolved in southwest Louisiana in the early 19th century from forms of Louisiana Creole music. Usually fast tempo and dominated by the button or piano accordion and a form of a washboard known as a vest frottoir, zydeco music was originally created at house dances, where families and friends gathered for socializing.

For 150 years, Louisiana Creoles enjoyed an insular lifestyle, prospering, educating themselves without the American government and building their invisible communities under the Code Noir. The French created the Code Noir in 1724 to establish rules for treatment of slaves, as well as restrictions and rights for gens de couleur libres, a growing class of free people of color who had the right to own land, something few blacks in the American South had at that time.

The music arose as a synthesis of traditional Creole music, some Cajun music influences, and African-American traditions, including blues and gospel. It was also often just called French music. Zydeco’s rural beginnings and the prevailing economic conditions at its inception are reflected in many of the song titles and lyrics.

It moved to rural dance halls and nightclubs. As a result, the music integrated waltzes, shuffles, two-steps, and most dance music forms of the era. Today, the tradition of change and evolution in the music continues. It stays current while integrating even more genres such as hip-hop, ska, rock, and other styles, in addition to the traditional zydeco forms.

An instrument used in Zydeco music is the vest frottoir. It is usually made from pressed, corrugated aluminium and is worn over the shoulders. Other instruments common in zydeco include the old world accordion which is found in folk and roots music globally.

Mycena is a large genus of small saprotrophic mushrooms which are rarely more than a few centimeters in width. They are characterized by a white spore print, a small conical or bell-shaped cap, and a thin fragile stem. Most are grey or brown, but a few species have brighter colors. Most have a translucent and striate cap, which rarely has an incurved margin. The gills are attached and usually have cystidia or large elongated cells. A few of the species exude a latex when the stem is broken, and many have the odor of bleach.

Mycenas are hard to identify to species and some are distinguishable only by microscopic features such as the shape of the cystidia. Some species are known to be edible, while some are known to contain toxins, but most of them are not known, as they are too small to be useful in cooking. Mycena cyanorrhiza stains blue and contains the hallucinogen psilocybin and Mycena pura contains the mycotoxin muscarine.

Thirty-three species are known to be bioluminescent, creating a glow known as foxfire. These species are divided among 16 lineages, leading to evolutionary uncertainty in whether the luminescence developed once and was lost among many species, or evolved in parallel by several species. The evolutionary purpose of the glowing is uncertain.

Norteño, literally meaning “northern” in Spanish, is a genre of Mexican music. The accordion and the bajo sexto are norteño’s most characteristic instruments. This genre of music is extremely popular among some in both Mexico and the United States, especially among the Mexican community. Though originating from rural areas, norteño is highly popular in urban as well as rural areas. 

During the late 19th century, German and Czech migrants to Northern Mexico and the U.S. Southwest brought different styles among them: la redova, la varsoviana and the polka. These European immigrants fueled the demand for a local brewing industry, and they also influenced the music scene by bringing the accordion and the polka rhythm, which were part of the popular music of their homeland. Soon, local bands adopted these elements, and a new unique style gradually resulted from a blend with Mexican ranchera styles. This new style soon became a unique norteño genre, thus named because it was primarily popular in the northern regions of Mexico.

In the late 1910s and 1920s, the corridos entered a golden age when Mexicans on both sides of the border recorded in San Antonio area hotels, revolutionizing the genre alongside Mexico’s political revolution. Traditionally, norteño bands played corridos, polkas, and rancheras.

In the 1950s, the heavy influence of Norteño on the traditional music of Mexican-Americans in southern Texas gave rise to a new form of popular music, called Tejano or “Tex-Mex”, which is often influenced by American rock and swing. Tejano music often includes English and may sound much more like American rock and country music, but is a broad genre of music incorporating many different styles, all having origin in traditional Texas Mexican music.

Norteño became even more popular in the 1990s and 2000s in the United States as the Latino-American community increased rapidly. Norteño continues to be one of the most popular types of modern Mexican music today, but it is also gaining rapid popularity in the United States. Many of the most famous Mexican bands such as Ramón Ayala y sus Bravos del Norte, Los Dueto Voces del Rancho, Grupo Móntez de Durango, and Los Rieleros del Norte are all based in the United States with American labels, and their music is usually recorded and produced within the United States. This trend follows the rapid integration of Mexican-American immigrants into the United States. As norteño music is increasingly becoming integrated into American society, norteño, banda, and duranguense are not only Mexican music but also, to some extent, music of the United States.

Thought is a mental process which allows an individual to model the world, and so to deal with it effectively according to their goals, plans, ends and desires. Words referring to similar concepts and processes include cognition, idea, and imagination. Thinking involves the cerebral manipulation of information, as when we form concepts, engage in problem solving, reasoning and making decisions. Thinking is a higher cognitive function and the analysis of thinking processes is part of cognitive psychology.

Memory is an organism’s ability to store, retain, and subsequently recall information. Although traditional studies of memory began in the realms of philosophy, the late nineteenth and early twentieth century put memory within the paradigms of cognitive psychology. In recent decades, it has become one of the principal pillars of a new branch of science called cognitive neuroscience, a marriage between cognitive psychology and neuroscience.

Imagination is accepted as the innate ability and process to invent partial or complete personal realms the mind derives from sense perceptions of the shared world. The term is technically used in psychology for the process of reviving in the mind percepts of objects formerly given in sense perception. Imagined images are seen with the “mind’s eye”. One hypothesis for the evolution of human imagination is that it allowed conscious beings to solve problems, and hence increase an individual’s fitness, by use of mental simulation.

Consciousness in mammals including humans, is an aspect of the mind generally thought to comprise qualities such as subjectivity, sentience, and the ability to perceive the relationship between oneself and one’s environment. It is a subject of much research in philosophy of mind, psychology, neuroscience, and cognitive science. Some philosophers divide consciousness into phenomenal consciousness, which is subjective experience itself, and access consciousness, which refers to the global availability of information to processing systems in the brain. Phenomenal consciousness has many different experienced qualities, often referred to as qualia.

The evolution of complexity is an important outcome of the process of evolution. Evolution has produced some remarkably complex organisms, although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all being used to assess an organism’s complexity.

This observation that complex organisms can be produced from simpler ones has led to the common misperception of evolution being progressive and having a direction that leads towards what are viewed as higher organisms.

In the 19th century, some scientists believed that all Nature had an innate striving to become more complex with evolution. This belief may reflect then-current ideas that all creation was gradually evolving to a higher, more perfect state.

According to this view, the evolution of parasites from a basic organism to parasite was seen as “devolution” and contrary to nature. This view has sometimes been used metaphorically by social theorists and propagandists to decry a class of people as degenerate parasites. Today, “devolution” is regarded as nonsense; rather, lineages will become simpler or more complicated according to whatever forms have a selective advantage.

Organisms that reproduce more quickly and plentifully than their competitors have an evolutionary advantage. Consequently, organisms can evolve to become simpler and thus multiply faster and produce more offspring, as they require fewer resources to reproduce. A good example are parasites such as malaria and mycoplasma, These organisms often dispense with traits that are made unnecessary through parasitism on a host.

However, evolution can also produce more complex organisms. Complexity often arises in the co-evolution of hosts and pathogens, with each side developing ever more sophisticated adaptations, such as the immune system and the many techniques pathogens have developed to evade it. 

More generally, the growth of complexity may be driven by the co-evolution between an organism and the ecosystem of predators, prey and parasites to which it tries to stay adapted. Any of these become more complex in order to cope better with the diversity of threats offered by the ecosystem formed by the others, the others will also have to adapt by becoming more complex, thus triggering an on-going evolutionary arms race towards more complexity. This trend may be reinforced by the fact that ecosystems themselves tend to become more complex over time as species diversity increases, together with the linkages or dependencies between species.

A planetesimal is a solid object arising during the accumulation of planets whose internal strength is dominated by self gravity and whose orbital dynamic is not significantly affected by gas drag. This corresponds to objects with a diameter larger than approximately 1 mile in the solar nebula. The word planetesimal comes from the mathematical concept infinitesimal and literally means an ultimately small fraction of a planet.

While the name is always applied to small bodies during the process of planet formation, some scientists also use the term planetesimal as a general term to refer to many small solar system bodies such as asteroids which are left over from the formation process.

In the current Solar System, these small bodies are usually also classified by dynamics and composition, and may have subsequently evolved to become comets or Kuiper belt objects. In other words, some planetesimals became other populations once planetary formation had finished, and may be referred to by either or both names.

It is generally believed that about 3.8 billion years ago, after a period known as the Late Heavy Bombardment, most of the planetesimals within the solar system had either been ejected from the solar system entirely, into distant eccentric orbits such as the Oort cloud, or had collided with larger objects due to the regular gravitational nudges from the planets between Jupiter and Neptune. A few planetesimals may have been captured as moons, such as the moons of Mars, Phobos and Deimos, and many of the small high-inclination moons of the Jovian planets.

A widely accepted theory of planet formation states that planets form out of dust grains that collide and stick to form larger and larger bodies. When the bodies reach sizes of approximately one kilometer, then they can attract each other directly through their mutual gravity, aiding further growth into moon-sized protoplanets enormously. This is how planetesimals are often defined.

Bodies that are smaller than planetesimals must rely on Brownian motion or turbulent motions in the gas to cause the collisions that can lead to sticking. Alternatively, planetesimals can form in a very dense layer of dust grains that undergoes a collective gravitational instability in the mid-plane of a protoplanetary disk. Many planetesimals may eventually break apart during violent collisions, but a few of the largest planetesimals can survive such encounters and continue to grow into protoplanets and later, planets.

Planetesimals that have survived to the current day are valuable to scientists because they contain information about the birth of our solar system. Although their exteriors are subjected to intense solar radiation that can alter their chemistry, their interiors contain pristine material essentially untouched since the planetesimal was formed. This makes each planetesimal a “time capsule”, and their composition can tell us of the conditions in the Solar Nebula from which our planetary system was formed.

Lichens are composite organisms consisting of a symbiotic association of a fungus with a photosynthetic partner, usually either a green algae or cyanobacterium. The morphology, physiology and biochemistry of lichens are very different to that of isolated fungus and algae. Lichens occur in some of the most extreme environments on Earth, such as arctic tundra, hot deserts, rocky coasts and toxic slag heaps.

They are abundant on leaves and branches in rain forests and temperate woodland, on bare rock, including walls and gravestones, and on exposed soil surfaces in otherwise harsh habitats. Lichens are widespread and long-lived, however, many species are also vulnerable to environmental disturbance, and may be useful to scientists in assessing the effects of air pollution, ozone depletion, and metal contamination. Lichens have also been used in making dyes and perfumes, as well as in traditional medicines.

Lichens must compete with plants for access to sunlight, but because of their small size and slow growth, they thrive in places where higher plants have difficulty growing. Lichens are often the first to settle in places lacking soil, constituting the sole vegetation in some extreme environments such as those found at high mountain elevations and cooler latitudes. Some survive in the tough conditions of deserts, and others on frozen soil of the Arctic regions. Recent research shows that lichen can even endure extended exposure to space.

The form of most lichens is quite different from those of either the fungus or alga growing separately, and may strikingly resemble simple plants in form and growth. The fungus surrounds the algal cells, often enclosing them within complex fungal tissues unique to lichen associations. In many species the fungus penetrates the algal cell wall, forming penetration nodes or roots similar to those produced by pathogenic fungi.

The algal or cyanobacterial cells are photosynthetic, and as in higher plants they reduce atmospheric carbon dioxide into organic carbon sugars to feed both symbionts. Both partners gain water and mineral nutrients mainly from the atmosphere, through rain and dust. The fungal partner protects the algae by retaining water, serving as a larger capture area for mineral nutrients and, in some cases, provides minerals obtained from the substrate. If a bacteria is present as a primary partner or another symbiont in addition to green alga as in certain tripartite lichens, they can fix atmospheric nitrogen, complementing the activities of the green algae.

Lichens are capable of surviving extremely low levels of water content. However, the reconfiguration of membranes following a period of dehydration requires several minutes at least. During this period a solution of metabolites from both the fungus and plant leaks into the extracellar spaces. This is readily available to both forms to take up essential metabolic products ensuring a perfect level of mutualism. Other epiphytic organisms may also benefit from this nutrient rich base. This phenomenon also points to a possible explanation of lichen evolution from its original components with its subsequent migration from an aquatic environment to dry land. Thus, during repeated periods of dehydration in an algae and the resultant leakage of beneficial metabolites to an adjacent aquatic fungus, the mutalistic patterns slowly became constant.

Lichens may be eaten by some animals, such as reindeer living in arctic regions. The larvae of a surprising number of Lepidoptera moth and butterfly species feed exclusively on lichens. These include Common Footman and Marbled Beauty. Lichens are also used by the Northern Flying Squirrel for nesting, food, and a water source during winter.

Extracts from many lichen species were used to treat wounds in Russia in the mid-twentieth century. The lichen Umbilicaria esculenta is collected from cliffs for use in a variety of traditional Korean and Japanese foods.

Many lichens produce secondary compounds, including pigments that reduce harmful amounts of sunlight and powerful toxins that reduce herbivory or kill bacteria. These compounds are very useful for lichen identification, and have had economic importance as dyes such as cudbear or primitive antibiotics.

There are reports dating almost 2000 years of lichens being used to extract purple and red colors. Of great historical and commercial significance are lichens belonging to the family Roccellaceae, commonly called orchella weed. The pH indicator litmus is a dye extracted from the lichen genus Rocella tinctoria by boiling.