Science & Philosophy: Methane to Molecular clock
Metric System - Measuring Units In Folklore And History, The Metric Units, Bigger And Smaller Metric Units, Converting Between English And Metric Units
The metric system of measurement is an internationally agreed-upon set of units for expressing the amounts of various quantities such as length, mass, time, temperature, and so on. Whenever we measure something, from the weight of a sack of potatoes to the distance to the moon, we must express the result as a number of specific units: for example, pounds and miles in the English system of measurem…
Mice - New World Mice (hesperomyinae), Deer Mice, House Mice, Wood Mice, Spiny Mice - Old World mice (Murinae)
Mice are small fury mammals, usually living on the ground, with bright beady eyes, rounded ears, and long tails. Mice live all around the world, in almost every habitat, and are a very important part of nature. They are typically vegetarians, often eating seeds and grain, but some species have developed much more comprehensive diets. Known for their high rates of reproduction, females are normally…
Microbial Genetics
Microorganisms include prokaryotes like bacteria, unicellular or mycelial eukaryotes e.g., yeasts and other fungi, and viruses, notably bacterial viruses (bacteriophages). Microbial genetics is concerned with the transmission of hereditary characters in microorganisms. Microbial genetics has played a unique role in developing the fields of molecular and cell biology and also has found applications…
Microclimate
Climate is the set of characteristic temperatures, humidities, sunshine, winds, and other weather conditions that prevail over large areas of space for long periods of time. Microclimate refers to a climate that holds over a very small area. Microclimates usually are slight modifications of the main background climate altered by features in the landscape. A forest creates a microclimate within the…
Microcosm and Macrocosm - Origins, Plato, The Body Politic, Hellenism And Late Antiquity, Jewish And Muslim Theories In The Middle Ages
Microcosm and macrocosm are two aspects of a theory developed by ancient Greek philosophers to describe human beings and their place in the universe. These early thinkers viewed the individual human being as a little world (mikros kosmos) whose composition and structure correspond to that of the universe, or great world (makros kosmos, or megas kosmos). Kosmos at this time meant "order�…
Microorganisms
Microorganisms are minute organisms of microscopic dimensions, too small to be seen by the eye alone. To be viewed, microorganisms must be magnified by an optical or electron microscope. The most common types of microorganisms are viruses, bacteria, blue-green bacteria, some algae, some fungi, yeasts, and protozoans. Viruses, bacteria, and blue-green bacteria are all prokaryotes, meaning that they…
Microscope - A Brief History Of Microscopy, Various Types Of Optical Microscopes, Electron Microscope, Other Types Of Microscopes
A microscope magnifies and resolves the image of an object that otherwise would be invisible to the naked eye, or whose detail could not be resolved using the unaided eye. These objects include such items as human skin, the eye of a fly, cells of a living organism, microorganisms such as bacteria, protozoa and viruses, individual molecules, and atoms. Some of the above objects are large enough to …
Microtechnology - Computer Microtechnology, Lasers, Scientific And Medical Microtechnology, Space Microtechnology
Microtechnology is the use of compact, or very small, technical devices. Microtechnology embraces microcomputer parts, space microdevices, microsurgery, and microelectronics. Both microfilm and microfiche, which store information on film, are also examples of microtechnology; microfiche generally stores more than microfilm. The term "micro," derived from the Greek word mikros, meanin…
Microwave Communication - Microwaves And Power, Spatial Diversity, Microwave Propagation, Microwave Path Loss - Microwave transmitters, Satellites and microwaves
Microwaves are radio signals with a very short wavelength. Microwave signals can be focused by antennas just as a searchlight concentrates light into a narrow beam. Signals are transmitted directly from a source to a receiver site. Reliable microwave signal range does not extend very far beyond the visible horizon. If microwave signals were visible to the eye, cities would be seen to be crisscross…
Migraine Headache - Treatment, Alternative Treatments, Prevention - Causes and symptoms, Diagnosis, Prognosis
Migraine is a type of headache marked by severe head pain lasting several hours or more. Migraine is an intense, often debilitating type of headache. Migraines affect as many as 24 million people in the United States, and are responsible for billions of dollars in lost work, poor job performance, and direct medical costs. Approximately 18% of women and 6% of men experience at least one migraine at…
Migration in World History - Patterns Of Migration, Governmental Policies, Global Versus Nationalist Perspectives, Bibliography
Migration is a central aspect of human existence. This is evident from the debate about the origins of the human species, which spread, according to the evidence, from Africa across all continents. On the level of ideas and prejudices, this has resulted in racialized debates about white distinctiveness and Afrocentrism. In prehistoric times, some thirty to forty thousand years ago, human beings m…
Mildew
Mildews are whitish fungi that grow on moist surfaces. Some mildews are parasites growing on the surface of plant foliage or fruits. Other mildews grow on the moistened surfaces of materials made from plant or animal tissues, such as wood, paper, clothing, or leather. The downy mildews are in the fungal family Peronosporaceae. These fungi can only exist as parasites, and under conditions favorable…
Milkweeds
Milkweeds are various species of perennial plants in the family Asclepiadaceae, a mostly tropical group that contains more than 1,800 species. Most species in this Milkweed in seed. JLM Visuals. Reproduced by permission. family are herbaceous, but others are woody climbers, shrubs, or small trees. The foliage and stems of milkweeds are often succulent, and when they are broken they weep a whi…
Millenarianism - Origins Of Millenarianism, Millenarian Movements, Millenarianism In North America, Bibliography
Millenarianism refers to religious beliefs about a thousand-year period at the end of the world. This period, the millennium (from two Latin words, mille, thousand, and annum, year), is described in the Bible's Book of Revelation (20:1–6). Millenarians, while believing that Christ's Second Coming will usher in this earthly kingdom for the faithful, differ on the timing of the …
Miller-Urey Experiment
A classic experiment in molecular biology and genetics, the Miller-Urey experiment, established that the conditions that existed in Earth's primitive atmosphere were sufficient to produce amino acids, the subunits of proteins comprising and required by living organisms. In essence, the Miller-Urey experiment fundamentally established that Earth's primitive atmosphere was capable of p…
Millipedes
Millipedes are long, cylindrical, segmented, many-legged terrestrial arthropods in the class Diplopoda, in total comprising about 10,000 species. The common name of these animals is derived from the Latin word for "thousand legs," although most species actually have fewer than 200 legs, and some as few as about 60. Millipedes have an elongate, almost cylindrical body form, with two s…
Mineralogy - Minerals and history, Branches of mineralogy
Mineralogy is the branch of geology concerned with the study of minerals. A mineral is a naturally occurring, homogeneous solid with a definite chemical composition and a highly ordered atomic structure. A homogeneous substance is one that can be divided into repeating units that are exactly the same. A mineral, by definition, cannot be a liquid or a gas. The chemical composition of a mineral is d…
Minerals - Chemical Bonding And Crystal Structure, Chemical Bonding, Crystal Structure, Physical Traits And Mineral Identification - Mineral groups
In ordinary usage, minerals are the natural, non-living materials that compose rocks and are mined from Earth. Examples are metals, gemstones, clays, and ores. The scientific definition of a mineral is more limited. To be considered a mineral, a substance must be solid under ordinary conditions, thus excluding petroleum and water. Minerals must be single, homogeneous (uniform) substances. Therefor…
Mining - History Of Mining, Surface Mining, Underground Mining
Mining is the process by which ores or related materials are extracted from the Earth. Ore is defined as a rock or mineral, generally metallic, which can be mined, processed, transported, and sold at a profit. Therefore, the classification of an Earth material as ore depends as much on economics and technology as geology. Nonmetallic substances that are commonly mined but not considered to be ores…
Mink - Species of minks
Minks are carnivores in the family Mustelidae, which also includes badgers, weasels, marten, and otters. Mink are closely related to the weasels and ermine, and are included in the same genus (Mustela spp.). Mink have a long, compact body, with relatively short legs, webbed toes, and a long, bushy tail. Minks are larger and more stout than other animals in the weasel group. Male minks are consider…
Minnows - The minnow family in North America
Minnows are a diverse group of about 1,600 species of small exclusively freshwater fish in the family Cyprinidae. The most familiar of these fish are carp, minnows, tenche, and barbs. Species in the minnow family occur in Africa, Asia, Europe, and North America. In addition, some cultivated and game species have also been introduced to South America, New Guinea, Australia, New Zealand, and some ot…
Minority - Widening The Definition, Minority Status And The Individual, Bibliography
The term minority group and its opposite, majority group, have been widely used both among social scientists and the general public in recent decades. In social scientific (and often popular) use of these terms, they do not usually refer per se to a numerical minority or majority. Rather, the social-scientific meaning of a minority group is a group that is assigned an inferior status in society, o…
Mir Space Station - Design And Construction, Collaboration
The longest continuous presence of man in space began in 1989, with the Russian launch of a 20.4 ton cylinder that formed the core of the space station called Mir. By 1996, a total of six modules had been linked to complete the sprawling station, which has been likened to a spaceborne assembly of tinkertoys. To build Mir, the Russians drew from lessons learned with the Salyut stations of the 1970s…
Miracles - Miracles As Narrative Constructions, Miracles In Sacred Scriptures, Bibliography
Miracles, miracle workers, and their stories are found in the life and literature of all ancient societies and are not limited to religious texts. In ancient Greece figures like Epimenides, Pythagoras, and Apollonius of Tyana were all renowned for working miracles. To this day, healing remains the form that most claimed miracles take, and many of these miracles are associated with visitations to t…
Mirrors
Any reflective material can act as a mirror, because it will throw back enough light to form an image of its surroundings. The surface may be a plane, concave or convex. Planar or flat mirrors present a virtual image that reverses the object being reflected. Curved surfaces act more like lenses, without the aberrations to which glass lenses are prone. Nowadays such surfaces can be made from glass,…
Miscibility
Miscibility means how completely two or more liquids dissolve in each other. It is a qualitative rather than quantitative observation—miscible, partially miscible, not miscible. (To state exactly how miscible two liquids were, a scientist would use the larger concept of solubility, usually in a specific weight or volume per liter of solution.) Two completely miscible liquids will form a hom…
Mistletoe
Mistletoe belongs to the family Viscaceae and to the genus Viscum, Phoradendron, or Arceuthobium. Most commonly, mistletoe refers to either the Eurasian shrub Viscum album or one of the American species, such as Phoradendron flavescens. Mistletoe grows on the trunks and branches of a wide variety of trees. Mistletoe is an evergreen, and its stems have numerous branches. The plants have tough, oblo…
Mites
Mites are tiny arthropods in the order Acari (or Acarina), which also includes the somewhat larger ticks. The Acari is in the class Arachnida, which also encompasses the spiders and scorpions. Arachnids have four pairs of segmented legs, a body divided into a cephalothorax (that is, a united head and thorax), and abdomen, and they have a simple respiratory apparatus consisting of tracheae and/or b…
Mitosis - Prophase, Anaphase, Cytokinesis - Metaphase, Telophase
Mitosis is a process that sorts and evenly distributes a cell's genetic instructions to the nuclei of two daughter cells during cell division. Mitosis distributes identical DNA instructions to new cells when the old cell divides. Growth is based on cell division and mitosis. Some cells in the body—such as nerve and skeletal muscle cells—cannot divide, and they stay with us for…
Chemical Mixture
A chemical mixture is a collection of molecules or atoms of different types. A mixture is distinguished from a pure substance, which has constant composition (is composed of a only one type of molecule or atom), and a unique set of physical properties (no matter how large or small a sample is observed). The properties of a mixture depend not only on the types of substances that compose it, but als…
Mockingbirds and Thrashers
Mockingbirds, thrashers, and catbirds are 31 species of medium-sized birds that are sometimes known as mimid thrushes, in the family Mimidae. This is an American family of birds, occurring widely from southern Argentina and Chile, through to southern Canada. The usual habitat of mimids is brushlands, forest edges, shrubby riparian areas, and recently disturbed forests. Mimids range in body length …
Modern Judaism - Dynamics Of Westernization, Bibliography
Judaism has never been monolithically uniform. Made irreducibly complex by 3,500 years of turbulent history, it resists simplification. Its data refuse to be straitjacketed or handled dispassionately. Impartial attempts to understand it are easily spoiled by the partisan sympathies and deeply held antagonisms it activates in observers. Consider a mere sampling of the evidence. Its implications sta…
Philosophy of Modern Language - Logical Syntax And Semantics, Logical Positivism And Its Challengers, Philosophy Of Language Since Quine, Bibliography - Founders of the Twentieth-Century "Linguistic Turn"
Although discussions of language in seventeenth-and eighteenth-century philosophy foreshadowed many issues that came to full bloom in the twentieth century, before the twentieth century language was thought to have a secondary role in understanding the special place human beings have in the world. The fundamental concern was the problem of knowledge. How is it possible for human beings to have kno…
Modernism - Impressionism, Symbolism, Oppositional Culture, The Assertion Of Modernism, 1890–1914, High Modernism And The Avant-garde, 1914–1930
A movement of indeterminate origin and span, modernism nevertheless retains the distinctiveness of a major episode in the history of culture. Its most renowned manifestations performed a radical break with the dominant arts of the nineteenth century. They were direct provocations to prevailing norms: norms of beauty, of the representational integrity of the human body, of the continuity of forms, …
Modernism - Latin America - The Origin Of "modernism" In Latin America, Modernism And Postmodernism, Conclusions, Bibliography
Modernism (sometimes referred to as modern art or, even less precisely, as modernity in the arts) is a term for various experimental languages in the arts with multiple meanings and conflicting aims, and was ascendant from the 1880s to the 1960s (although certain artistic techniques and tactics of early modernist art, such as collage and photomontage, have enjoyed a potent afterlife since the 1960…
Modernist Anthropological Theory of Family - The Family In Early Social Evolutionary Theory, The Modernist Study Of Kinship, Bibliography
In their efforts to bring some analytical rigor to the study of this confusing but important concept, anthropologists have come to speak not of "the family" but of "kinship," a larger, more inclusive category that can refer to any and all of the ways in which we find or forge relationships between ourselves and others, although it is usually confined to those relationsh…
Modernity - Bibliography
Modernity is best understood as a condition, rather than as the designation for some particular period of time. Aspects of the modern condition can arise at any time and place, but they are most generally associated with historical trends arising out of Cartesian philosophy, industrial capitalism, revolutionary politics, and the cultural changes of the turn of the nineteenth century. The main less…
Modernity - Africa - Signs Of Modernity, Colonial Modernities, Bibliography
The debates and controversies over modernity, from its origins in sixteenth-and seventeenth-century western Europe to the various sites of its deployment following the formation of colonial empires, have given rise to an abundance of literature. Non-Western societies, by and large, in the formation of their cultural, political, economic, and social identities and their reactions to it, have approp…
Modernity - East Asia - Civilization And Enlightenment: Meiji Japan (1868–1912), Belated Enlightenment: China (1880s–1920s), Urban Cosmopolitan Modernity (1920s–1930s)
Modernity (kindaisei in Japanese, and xiandaixing in Chinese) is a relatively recent term in the intellectual vocabulary of East Asia, becoming current only after World War II. Differing conceptions of "the modern" start much earlier, when terms long available in both languages acquired new connotations, as the region felt the impact of the West. The classical Chinese jin (close, nea…
Modernization - Bibliography
The term modernization conjures images of social change in the direction of general improvement over the past. In contemporary social sciences, the notion has been the basis of a theoretical orientation—variously referred to as modernization theory, approach, paradigm, or framework—to the study of the development of Third World or underdeveloped societies. The conception of developme…
Modernization Theory - Defining Modernization Theory, Applying Modernization Theory, Globalization Theory, Contemporary Theories, Bibliography
For roughly one decade until the second half of the 1960s, modernization theory was in vogue in the social sciences, especially in the United States. The word modernization appeared widely in titles, the concept was commonly invoked in efforts to explain long-term change, and it figured in critiques of Marxist theory and discussions of Cold War differences over how newly independent countries shou…
Modular Arithmetic
Modular arithmetic derives from the concept of congruence modulo m, written symbolically as where a and b are any integers and m is a positive integer greater than 1. This means that a - b is divisible by m. For example, since 36 - 16 = 20 is divisible by 5. Likewise 11 ≡38 (mod 9) because 11-38 = -27 is divisible by 9. The concept of congruence was first used by Carl Friedrich Ga…
Mohs' Scale
Mohs' hardness scale provides an index and relative measure of mineral hardness (i.e., resistance to abrasion). In 1812, German geologist Frierich Mohs (1773–1839) devised a scale with specimen minerals that offered comparison of hardness qualities that allows the assignment of a Mohs hardness number to a mineral. Mohs' scale utilizes ten specific representative materials that…
Mold - Beneficial molds history
Molds are fungi that are microscopic in size. Even though they can approximate bacteria in size, molds are eukaryotic organisms. That is, their genetic material is enclosed within a specialized membrane that lies in the interior of the organism. Molds are present in virtually every environment that has been examined. Molds grow indoors and outdoors and, depending on the species, can grow year-roun…
Mole
A standard unit for counting numbers of particles is needed in chemistry, because atoms and molecules react with one another particle by particle. The amount of a chemical reaction—how much of the chemicals are used up or produced—is determined by the numbers of particles that are reacting. Weighing the chemicals wouldn't tell us anything very meaningful unless we knew how to …
Mole-Rats - Physical Attributes, Living Environment, Social Life
Mole-rats are small, fossorial rodents, which means they spend their entire lives underground in a sealed burrow system. Native to Africa, these little animals are found from the southernmost tip of the continent to about 10 degrees north of the equator. Mole-rats make up the family Bathyergidae, which includes 12 species in five genera (not to be confused with an unrelated family Spalacidae, cont…
Molecular Biology
Molecular biology is the study of biological molecules and the molecular basis of structure and function in living organisms. Molecular biology is an interdisciplinary approach to understanding biological functions and regulation at the level of molecules such as nucleic acids, proteins, and carbohydrates. Following the rapid advances in biological science brought about by the development and adva…
Molecular Formula
The molecular formula specifies the actual number of atoms of each element in a molecule. It is important to remember that the molecular formula—in contrast to the simpler empirical formula that specifies only the relative number of atoms or moles present in a compound—identifies the actual number of atoms present in a molecule. More information is required to construct a molecular f…
Molecular Weight
To know more about "molecular weights," one must first become familiar with the concept of "atomic weights." Because an element (e.g., carbon, oxygen, sulfur, etc.) often exists as a mixture of two or more (stable and unstable forms) natural isotopes that have the same number of protons but differ in the number of neutrons, atomic masses of these isotopes are slightly d…