Seedless nonflowering plants of the class Filicinae. They reproduce by spores that appear as dots on the underside of feathery fronds. In earlier classifications the Pteridophyta included the club mosses, horsetails, ferns, and various fossil groups. In more recent classifications, pteridophytes and spermatophytes (seed-bearing plants) are classified in the Subkingdom Tracheobionta (also known as Tracheophyta).
A plant genus of the family DENNSTAEDTIACEAE. Members contain ptaquiloside, braxin A1, and braxin B. The name is similar to brake fern (PTERIS).
A plant genus of the family POLYPODIACEAE. Members contain polypodoside.
A plant genus of the family DRYOPTERIDACEAE. Members contain aspidin and filicic acid.
A structure found in plants, fungi, and algae, that produces and contains spores.
Patterns (real or mathematical) which look similar at different scales, for example the network of airways in the lung which shows similar branching patterns at progressively higher magnifications. Natural fractals are self-similar across a finite range of scales while mathematical fractals are the same across an infinite range. Many natural, including biological, structures are fractal (or fractal-like). Fractals are related to "chaos" (see NONLINEAR DYNAMICS) in that chaotic processes can produce fractal structures in nature, and appropriate representations of chaotic processes usually reveal self-similarity over time.
Encyclopedias as Topic
A set of cognitive functions that controls complex, goal-directed thought and behavior. Executive function involves multiple domains, such as CONCEPT FORMATION, goal management, cognitive flexibility, INHIBITION control, and WORKING MEMORY. Impaired executive function is seen in a range of disorders, e.g., SCHIZOPHRENIA; and ADHD.
The bestowing of tangible or intangible benefits, voluntarily and usually without expectation of anything in return. However, gift giving may be motivated by feelings of ALTRUISM or gratitude, by a sense of obligation, or by the hope of receiving something in return.
A plant species of the family VISCACEAE, order Santalales, subclass Rosidae. This is the traditional mistletoe of literature and Christmas. Members contain viscotoxin (5 kDa basic polypeptides related to thionins), beta-galactoside- and N-acetyl-D-galactosamine-specific lectin II (60 kDa), and polysaccharides. Mistletoe lectin I is a type 2 ribosome-inactivating protein. Commercial extracts include Plenosol, Eurixor, Helixor Isorel, Iscador, and NSC 635089 (ANTINEOPLASTIC AGENTS, PHYTOGENIC).
A class of plants within the Bryophyta comprising the mosses, which are found in both damp (including freshwater) and drier situations. Mosses possess erect or prostrate leafless stems, which give rise to leafless stalks bearing capsules. Spores formed in the capsules are released and grow to produce new plants. (Concise Dictionary of Biology, 1990). Many small plants bearing the name moss are in fact not mosses. The "moss" found on the north side of trees is actually a green alga (CHLOROPHYTA). Irish moss is really a red alga (RHODOPHYTA). Beard lichen (beard moss), Iceland moss, oak moss, and reindeer moss are actually LICHENS. Spanish moss is a common name for both LICHENS and an air plant (TILLANDSIA usneoides) of the pineapple family. Club moss is an evergreen herb of the family LYCOPODIACEAE.
A class of BRYOPHYTA which is best known for Sphagnum forming PEAT bogs.
A group of islands in the southwest Pacific. Its capital is Wellington. It was discovered by the Dutch explorer Abel Tasman in 1642 and circumnavigated by Cook in 1769. Colonized in 1840 by the New Zealand Company, it became a British crown colony in 1840 until 1907 when colonial status was terminated. New Zealand is a partly anglicized form of the original Dutch name Nieuw Zeeland, new sea land, possibly with reference to the Dutch province of Zeeland. (From Webster's New Geographical Dictionary, 1988, p842 & Room, Brewer's Dictionary of Names, 1992, p378)
A competitive team sport played on a rectangular field. This is the American or Canadian version of the game and also includes the form known as rugby. It does not include non-North American football (= SOCCER).
It is a form of protection provided by law. In the United States this protection is granted to authors of original works of authorship, including literary, dramatic, musical, artistic, and certain other intellectual works. This protection is available to both published and unpublished works. (from Circular of the United States Copyright Office, 6/30/2008)
Protective measures against unauthorized access to or interference with computer operating systems, telecommunications, or data structures, especially the modification, deletion, destruction, or release of data in computers. It includes methods of forestalling interference by computer viruses or so-called computer hackers aiming to compromise stored data.
The privacy of information and its protection against unauthorized disclosure.
The legal authority or formal permission from authorities to carry on certain activities which by law or regulation require such permission. It may be applied to licensure of institutions as well as individuals.
Individuals with a degree in veterinary medicine that provides them with training and qualifications to treat diseases and injuries of animals.