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Pak Protectors
Pak Breeders and Pak Protectors are two developmental stages of fictional life in Larry Niven's Known Space universe. The Pak first appeared in "The Adults", which appeared in ''Galaxy'' in 1967; this story was expanded into the novel ''Protector'' by Larry Niven (1973). The Pak also appear in several of Niven's later novels, notably those set in the Ringworld. '' Destroyer of Worlds'' depicts a confrontation between the Pak and the Puppeteers. Narrative purpose Niven has written that he invented the Protectors as a thought experiment to explain the common effects of aging on humans and to create a fictional evolutionary explanation for humans' long lives after females have passed reproductive age. Accordingly, most of the positive attributes of Protectors are based on negative human aging effects: swollen joints, decreased muscle-fat ratio, weakening heart, invariant diet, decreasing height, facial atrophy, leathery skin, hair loss, lack of sex drive, and tooth loss are all t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbiosis
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, must be of different species. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms". The term was subject to a century-long debate about whether it should specifically denote mutualism, as in lichens. Biologists have now abandoned that restriction. Symbiosis can be obligatory, which means that one or more of the symbionts depend on each other for survival, or facultative (optional), when they can generally live independently. Symbiosis is also classified by physical attachment. When symbionts form a single body it is called conjunctive symbiosis, while all other arrangements are called disjunctive symbiosis."symbiosis." Dorland's Illustrated Medical Dictionary. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amalgamated Regional Militia
Known Space is the fictional setting of about a dozen science fiction novels and several collections of short stories written by Larry Niven. It has also become a shared universe in the spin-off ''Man-Kzin Wars'' anthologies. The Internet Speculative Fiction Database (ISFDB) catalogs all works set in the fictional universe that includes Known Space under the series name Tales of Known Space, which was the title of a 1975 collection of Niven's short stories. The first-published work in the series, which was Niven's first published piece was "The Coldest Place", in the December 1964 issue of '' If'' magazine, edited by Frederik Pohl. This was the first-published work in the 1975 collection. The stories span approximately one thousand years of future history, from the first human explorations of the Solar System to the colonization of dozens of nearby systems. Late in the series, Known Space is an irregularly shaped "bubble" about 60 light-years across. The epithet "Known Space" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ringworld's Children
''Ringworld's Children'' is a 2004 science fiction novel by American writer Larry Niven, the fourth in the Ringworld series set in the Known Space universe. It describes the continuing adventures of Louis Wu and companions on Ringworld. Plot summary The novel's plot is largely concerned with the so-called Fringe War. All the intelligent species of Known Space are interested in the Ringworld. In the novel, they engage in a Cold War of sorts (actually begun in the previous novel, '' The Ringworld Throne'') on the fringe of the Ringworld star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speak .... References 2004 American novels 2004 science fiction novels American science fiction novels Known Space stories Novels by Larry Niven Tor Books books Fiction set in the 29th c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homo Sapiens
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, and language. Humans are highly social and tend to live in complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established a wide variety of values, social norms, and rituals, which bolster human society. Its intelligence and its desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of study. Although some scientists equate the term ''humans'' with all members of the genus ''Homo'', in common usage, it generally refers to ''Homo sapiens'', the only extant member. Anatomically mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Martian
Mars, the fourth planet from the Sun, has appeared as a setting in works of fiction since at least the mid-1600s. It became the most popular celestial object in fiction in the late 1800s as the Moon was evidently lifeless. At the time, the predominant genre depicting Mars was utopian fiction. Contemporaneously, the mistaken belief that there are canals on Mars emerged and made its way into fiction. ''The War of the Worlds'', H. G. Wells' story of an alien invasion of Earth by sinister Martians, was published in 1897 and went on to have a large influence on the science fiction genre. Life on Mars appeared frequently in fiction throughout the first half of the 1900s. Apart from enlightened as in the utopian works from the turn of the century, or evil as in the works inspired by Wells, intelligent and human-like Martians also began to be depicted as decadent, a portrayal that was popularized by Edgar Rice Burroughs in the '' Barsoom'' series and adopted by Leigh Brackett among othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genocide
Genocide is the intentional destruction of a people—usually defined as an ethnic, national, racial, or religious group—in whole or in part. Raphael Lemkin coined the term in 1944, combining the Greek word (, "race, people") with the Latin suffix ("act of killing").. In 1948, the United Nations Genocide Convention defined genocide as any of five "acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group." These five acts were: killing members of the group, causing them serious bodily or mental harm, imposing living conditions intended to destroy the group, preventing births, and forcibly transferring children out of the group. Victims are targeted because of their real or perceived membership of a group, not randomly. The Political Instability Task Force estimated that 43 genocides occurred between 1956 and 2016, resulting in about 50 million deaths. The UNHCR estimated that a further 50 million had been displac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abundance Of Elements In Earth's Crust
The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%). Estimates of elemental abundance are difficult because (a) the composition of the upper and lower crust are quite different, and (b) the composition of the continental crust can vary drastically by locality. David KringComposition of Earth's continental crust as inferred from the compositions of impact melt sheets Lunar and Planetary Science XXVIII List of abundance by element See also * Abundances of the elements (data page) * Atmospheric chemistry * Clarke number — lists of historical data and terminology * List of chemical elements This is a list of the 118 chemical elements which have been identified as of 2022. A chemical element, often simply called an element, is a type of atom which has the same number of protons in its atomic nucleus (i.e., the same atomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thallium Oxide
Thallium has several oxides: *Thallium(I) oxide Tl2O *Thallium(III) oxide Thallium(III) oxide, also known as thallic oxide, is a chemical compound of thallium and oxygen. It occurs in nature as the rare mineral avicennite. Its structure is related to that of Mn2O3 which has a bixbyite like structure. Tl2O3 is metallic w ... Tl2O3 * Thallium(I) superoxide or thallium dioxide TlO2 * Tl4O3 {{Short pages monitor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, these two parts are the neurocranium and the viscerocranium ( facial skeleton) that includes the mandible as its largest bone. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth. In humans these sensory structures are part of the facial skeleton. Functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to enable sound localisation of the direction and distance of sounds. In some animals, such as horned ungulates (mammals with hooves), the skull also has a defensive function by providing the mount (on the front ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Femoral Vein
In the human body, the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor hiatus (an opening in the adductor magnus muscle) as the continuation of the popliteal vein. It ends at the inferior margin of the inguinal ligament where it becomes the external iliac vein. The femoral vein bears valves which are mostly bicuspid and whose number is variable between individuals and often between left and right leg. Structure Segments *The common femoral vein is the segment of the femoral vein between the branching point of the deep femoral vein and the inferior margin of the inguinal ligament.Page 590 in: *The subsartorial vein or superficial femoral vein are designations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moment (physics)
In physics, a moment is a mathematical expression involving the product of a distance and physical quantity. Moments are usually defined with respect to a fixed reference point and refer to physical quantities located some distance from the reference point. In this way, the moment accounts for the quantity's location or arrangement. For example, the moment of force, often called torque, is the product of a force on an object and the distance from the reference point to the object. In principle, any physical quantity can be multiplied by a distance to produce a moment. Commonly used quantities include forces, masses, and electric charge distributions. Elaboration In its most basic form, a moment is the product of the distance to a point, raised to a power, and a physical quantity (such as force or electrical charge) at that point: : \mu_n = r^n\,Q, where Q is the physical quantity such as a force applied at a point, or a point charge, or a point mass, etc. If the quantity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
