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Shovel-shaped Incisors
Shovel-shaped incisors (or, more simply, shovel incisors) are incisors whose Glossary of dentistry, lingual surfaces are scooped as a consequence of lingual marginal ridges, Crown (tooth), crown curvature, or Basal (anatomy), basal Tubercle (anatomy), tubercles, either alone or in combination. Shovel-shaped incisors are significantly common in Indigenous peoples of the Americas, Amerindians from North America, North, Central America, Central, and South America. They are also common in East Asians and Central Asians, Inuit, and Aleut peoples of Siberian Yupik, Northeast Asia and North America (including but not limited to Inuit in eastern Alaska, Northern Canada, Arctic Canada, and Greenland). In certain European peoples, European and Demographics of Africa, African groups, shovel-shaped upper incisors are uncommon or not present. There is a spectrum of the degree of shoveled-ness, ranging on a scale from 0 to 7 of spatulate incisors to shoveled incisors. It was theorized that pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shovel Shaped Incisors
A shovel is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore. Most shovels are hand tools consisting of a broad blade fixed to a medium-length handle. Shovel blades are usually made of sheet steel or hard plastics and are very strong. Shovel handles are usually made of wood (especially specific varieties such as ash or maple) or glass-reinforced plastic (fiberglass). Hand shovel blades made of sheet steel usually have a folded seam or hem at the back to make a socket for the handle. This fold also commonly provides extra rigidity to the blade. The handles are usually riveted in place. A T-piece is commonly fitted to the end of the handle to aid grip and control where the shovel is designed for moving soil and heavy materials. These designs can all be easily mass-produced. The term ''shovel'' also applies to larger excavating machines called power shovels, which serve the same purpose—digging, lifting, and moving mater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Peoples
Europeans are the focus of European ethnology, the field of anthropology related to the various ethnic groups that reside in the states of Europe. Groups may be defined by common ancestry, language, faith, historical continuity, etc. There are no universally accepted and precise definitions of the terms "ethnic group" and "nationality", but in the context of European ethnography in particular, the terms ''ethnic group'', ''people'', ''nationality'' and ''ethno-linguistic group'' are used as mostly synonymous. Preference may vary in usage with respect to the situation specific to the individual countries of Europe, and the context in which they may be classified by those terms. The total number of national minority populations in Europe is estimated at 105 million people, or 14% of 770 million Europeans in 2002.Christoph Pan, Beate Sibylle Pfeil (2002), Minderheitenrechte in Europa. Handbuch der europäischen Volksgruppen', Braumüller, (Google Books, snippet view). Als2006 rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valine
Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain isopropyl group, making it a non-polar aliphatic amino acid. Valine is essential in humans, meaning the body cannot synthesize it; it must be obtained from dietary sources which are foods that contain proteins, such as meats, dairy products, soy products, beans and legumes. It is encoded by all codons starting with GU (GUU, GUC, GUA, and GUG). History and etymology Valine was first isolated from casein in 1901 by Hermann Emil Fischer. The name valine comes from its structural similarity to valeric acid, which in turn is named after the plant valerian due to the presence of the acid in the roots of the plant. Nomenclature According to IUPAC, carbon atoms forming v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-nucleotide Polymorphism
In genetics and bioinformatics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently large fraction of the population (e.g. 1% or more), many publications do not apply such a frequency threshold. For example, a Guanine, G nucleotide present at a specific location in a reference genome may be replaced by an Adenine, A in a minority of individuals. The two possible nucleotide variations of this SNP – G or A – are called alleles. SNPs can help explain differences in susceptibility to a wide range of diseases across a population. For example, a common SNP in the Factor H, CFH gene is associated with increased risk of age-related macular degeneration. Differences in the severity of an illness or response to treatments may also be manifestations of genetic variations caused by SNPs. For example, two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene and are the result of genetic differences. While many perform the same or similar biological roles, some isoforms have unique functions. A set of protein isoforms may be formed from alternative splicings, variable promoter usage, or other post-transcriptional modifications of a single gene; post-translational modifications are generally not considered. (For that, see Proteoforms.) Through RNA splicing mechanisms, mRNA has the ability to select different protein-coding segments (exons) of a gene, or even different parts of exons from RNA to form different mRNA sequences. Each unique sequence produces a specific form of a protein. The discovery of isoforms could explain the discrepancy between the small number of protein coding regions of genes revealed by the human genome project and the large diversity of proteins seen in an organism: different proteins enc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ectodysplasin A Receptor
Ectodysplasin A receptor (EDAR) is a protein that in humans is encoded by the ''EDAR'' gene. EDAR is a cell surface receptor for ectodysplasin A which plays an important role in the development of ectodermal tissues such as the skin. It is structurally related to members of the TNF receptor superfamily. Function ''EDAR'' and other genes provide instructions for making proteins that work together during embryonic development. These proteins form part of a signaling pathway that is critical for the interaction between two cell layers, the ectoderm and the mesoderm. In the early embryo, these cell layers form the basis for many of the body's organs and tissues. Ectoderm-mesoderm interactions are essential for the proper formation of several structures that arise from the ectoderm, including the skin, hair, nails, teeth, and sweat glands. Clinical significance Mutation in this gene have been associated with hypohidrotic ectodermal dysplasia, a disorder characterized by a lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allele
An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule. Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), but they can also have insertions and deletions of up to several thousand base pairs. Most alleles observed result in little or no change in the function or amount of the gene product(s) they code or regulate for. However, sometimes different alleles can result in different observable phenotypic traits, such as different pigmentation. A notable example of this is Gregor Mendel's discovery that the white and purple flower colors in pea plants were the result of a single gene with two alleles. Nearly all multicellular organisms have two sets of chromosomes at some point in their biological life cycle; that is, they are diploid. For a given locus, if the two chromosomes contain the same allele, they, and the organism, are homozygous with re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canine Tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, eye teeth, vampire teeth, or fangs, are the relatively long, pointed teeth. In the context of the upper jaw, they are also known as '' fangs''. They can appear more flattened, however, causing them to resemble incisors and leading them to be called ''incisiform''. They developed and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons. They are often the largest teeth in a mammal's mouth. Individuals of most species that develop them normally have four, two in the upper jaw and two in the lower, separated within each jaw by incisors; humans and dogs are examples. In most species, canines are the anterior-most teeth in the maxillary bone. The four canines in humans are the two upper maxillary canines and the two lower mandibular canines. They are specially prominent in dogs (Canidae), hence the name. Details There are generally four canine teeth: two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neanderthal
Neanderthals ( ; ''Homo neanderthalensis'' or sometimes ''H. sapiens neanderthalensis'') are an extinction, extinct group of archaic humans who inhabited Europe and Western and Central Asia during the Middle Pleistocene, Middle to Late Pleistocene. Neanderthal extinction occurred roughly 40,000 years ago with the immigration of modern humans (Cro-Magnons), but Neanderthals in Gibraltar may have persisted for thousands of years longer. The first recognised Neanderthal fossil, Neanderthal 1, was discovered in 1856 in the Neander Valley, Germany. At first, Neanderthal 1 was considered to be one of the racial hierarchy, lower races in accord with historical race concepts. As more fossils were discovered through the early 20th century, Neanderthals became characterised most especially by Marcellin Boule as a unique species of underdeveloped human. By the mid-20th century, human evolution was described as progressing from an apelike ancestor, through a "Neanderthal phase", ending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peking Man
Peking Man (''Homo erectus pekinensis'', originally "''Sinanthropus pekinensis''") is a subspecies of '' H. erectus'' which inhabited what is now northern China during the Middle Pleistocene. Its fossils have been found in a cave some southwest of Beijing (referred to in the West as Peking upon its first discovery), known as the Zhoukoudian Peking Man Site. The first fossil, a tooth, was discovered in 1921, and Zhoukoudian has since become the most productive ''H. erectus'' site in the world. Peking Man was instrumental in the foundation of Chinese anthropology, and fostered an important dialogue between Western and Eastern science. Peking Man became the centre of anthropological discussion, and was classified as a direct human ancestor, propping up the Out of Asia theory that humans evolved in Asia. Peking Man also played a vital role in the restructuring of Chinese identity following the Chinese Communist Revolution, and it was used to introduce the general populace to M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homo Erectus
''Homo erectus'' ( ) is an extinction, extinct species of Homo, archaic human from the Pleistocene, spanning nearly 2 million years. It is the first human species to evolve a humanlike body plan and human gait, gait, to early expansions of hominins out of Africa, leave Africa and colonize Asia and Europe, and to Control of fire by early humans, wield fire. ''H. erectus'' is the ancestor of later human species, including ''Homo heidelbergensis, H. heidelbergensis'' — the last common ancestor of human, modern humans, Neanderthals, and Denisovans. As such a widely distributed species both geographically and temporally, ''H. erectus'' anatomy varies considerably. Subspecies are sometimes recognized: ''Java Man, H. e. erectus'', ''Peking Man, H. e. pekinensis'', ''Solo Man, H. e. soloensis'', ''Homo ergaster, H. e. ergaster'', ''Dmanisi hominins, H. e. georgicus'', and ''Tautavel Man, H. e. tautavelensis''. The species was first species description, described by Eugène Dubois i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesial
This is a list of definitions of commonly used terms of location and direction in dentistry. This set of terms provides orientation within the oral cavity, much as anatomical terms of location provide orientation throughout the body. Terms Combining of terms Most of the principal terms can be combined using their corresponding combining forms (such as ''mesio-'' for ''mesial'' and ''disto-'' for ''distal''). They provide names for directions (vectors) and axes; for example, the coronoapical axis is the long axis of a tooth. Such combining yields terms such as those in the following list. The abbreviations should be used only in restricted contexts, where they are explicitly defined and help avoid extensive repetition (for example, a journal article that uses the term "mesiodistal" dozens of times might use the abbreviation "MD"). The abbreviations are ambiguous: (1) they are not spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
