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Chalk Boards
A blackboard or a chalkboard is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate or calcium carbonate, better known as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone. Design A blackboard can simply be a board painted with a dark matte paint (usually black, occasionally dark green). Matte black plastic sign material (known as closed-cell PVC foamboard) is also used to create custom chalkboard art. Blackboards on an A-frame are used by restaurants and bars to advertise daily specials. Adhesive chalkboard surface is also available in stores as rolls of textured black plastic shelf covering, which is applied to the desired wall, door or other surface. A more modern variation consists of a coiled sheet of plastic drawn across two parallel rollers, which can be scrolled to create additional writing space while saving what has been written. The highest grade blackboards are made of po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homer E
Homer (; , ; possibly born ) was an Ancient Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Despite doubts about his authorship, Homer is considered one of the most revered and influential authors in history. The ''Iliad'' centers on a quarrel between King Agamemnon and the warrior Achilles during the last year of the Trojan War. The ''Odyssey'' chronicles the ten-year journey of Odysseus, king of Ithaca, back to his home after the fall of Troy. The epics depict man's struggle, the ''Odyssey'' especially so, as Odysseus perseveres through the punishment of the gods. The poems are in Homeric Greek, also known as Epic Greek, a literary language that shows a mixture of features of the Ionic and Aeolic dialects from different centuries; the predominant influence is Eastern Ionic. Most researchers believe that the poems were originally transmitted orally. Despite being predomin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustical Society Of America
The Acoustical Society of America (ASA) is an international scientific society founded in 1929 dedicated to generating, disseminating and promoting the knowledge of acoustics and its practical applications. The Society is primarily a voluntary organization of about 7500 members and attracts the interest, commitment, and service of many professionals. History In the summer of 1928, (See Wallace Clement Sabine.) Floyd R. Watson and Wallace Waterfall (1900–1974), a former doctoral student of Watson, were invited by UCLA's Vern Oliver Knudsen to an evening dinner at Knudsen's beach club in Santa Monica. The three physicists decided to form a society of acoustical engineers interested in architectural acoustics. In the early part of December 1928, Wallace Waterfall sent letters to sixteen people inquiring about the possibility of organizing such a society. Harvey Fletcher offered the use of the Bell Telephone Laboratories at Bell Laboratories Building (Manhattan), 463 West Street in M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Cologne
The University of Cologne () is a university in Cologne, Germany. It was established in 1388. It closed in 1798 before being re-established in 1919. It is now one of the largest universities in Germany with around 45,187 students. The University of Cologne is a member of the U15 (German universities), German U15 association of major research-intensive universities and was a university of excellence as part of the German Universities Excellence Initiative from 2012 to 2019. It is constantly ranked among top 20 German universities in the world rankings. The University of Cologne has 5 Clusters of Excellence: CECAD Cluster of Excellence for Aging Research, Cluster of Excellence ECONtribute: Markets & Public Policy, CEPLAS Cluster of Excellence for Plant Sciences, ML4Q Cluster of Excellence Matter and Light for Quantum Information and DYNAVERSE Cluster of Excellence. As of 2025, among its notable alumni, faculty and researchers are 5 List of Nobel laureates, Nobel Laureates, 11 Le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Scientist
''New Scientist'' is a popular science magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publishes a monthly Dutch-language edition. First published on 22 November 1956, ''New Scientist'' has been available in online form since 1996. Sold in retail outlets (paper edition) and on subscription (paper and/or online), the magazine covers news, features, reviews and commentary on science, technology and their implications. ''New Scientist'' also publishes speculative articles, ranging from the technical to the philosophical. ''New Scientist'' was acquired by Daily Mail and General Trust (DMGT) in March 2021. History Ownership The magazine was founded in 1956 by Tom Margerison, Max Raison and Nicholas Harrison as ''The New Scientist'', with Issue 1 on 22 November 1956, priced at one shilling (). An article in the magazi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalkboard Scraping
Scraping a chalkboard (also known as a blackboard) with one's fingernails produces a sound and feeling which most people find extremely irritating. The basis of the innate reaction to the sound has been studied in the field of psychoacoustics (the branch of psychology concerned with the perception of sound and its physiological effects). Physiological response Brain stem reflex In response to audio stimuli, the mind's way of interpreting sound can be translated through a regulatory process called the reticular activating system. Located in the brain stem, the reticular activating system continually listens, even throughout delta-wave sleep, to determine the importance of sounds in relation to waking the cortex or the rest of the body from sleep. Chalkboard scraping, or noises that elicit an emotional response have been known to trigger tendencies from the fight or flight response which acts as the body's primary self-defense mechanism. Emotional response Distinct emotion A stu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Writing Utensil
A writing implement or writing instrument is an object used to produce writing. Writing consists of different figures, lines, and or forms. Most of these items can be also used for other functions such as painting, drawing and technical drawing, but writing instruments generally have the ordinary requirement to create a smooth, controllable line. Another writing implement employed by a smaller population is the stylus used in conjunction with the slate for punching out the dots in Braille. Autonomous An autonomous writing implement is one that cannot "run out"—the only way to render it useless is to destroy it. Without pigment The oldest known examples were created by incising a flat surface with a rigid tool rather than applying pigment with a secondary object, e.g., Chinese jiaguwen carved into turtle shells. However, this may simply represent the relative durability of such artifacts rather than truly representing the evolution of techniques, as the meaningful application ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computers
A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', which enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the hardware, operating system, software, and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of industrial and consumer products use computers as control systems, including simple special-purpose devices like microwave ovens and remote controls, and factory devices like industrial robots. Computers are at the core of general-purpose devices such as personal computers and mobile devices such as smartphones. Computers power the Internet, which links billions o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WebMD
WebMD is an American corporation which publishes online news and information about human health and well-being. The WebMD website also includes information about drugs and is an important healthcare information website and the most popular consumer-oriented health site. WebMD was started in 1998 by internet entrepreneur Jeff Arnold. In early 1999, it was part of a three-way merger with Sapient Health Network (SHN) and Direct Medical Knowledge (DMK). SHN began in Portland, Oregon, in 1996 by Jim Kean, Bill Kelly, and Kris Nybakken, who worked together at a CD-ROM publishing firm, Creative Multimedia. Later, in 1999, WebMD merged with Healtheon, founded by Netscape Communications founder James H. Clark. History WebMD is best known as a health information services website, which publishes content regarding health and health care topics, including a symptom checklist, pharmacy information, drugs information, and blogs of physicians with specific topics, and provides a place t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Academy Of Allergy, Asthma And Immunology
Founded in 1943, the American Academy of Allergy, Asthma & Immunology (AAAAI) is a professional medical membership organization of more than 7,000 allergists/ immunologists and related professionals around the world with advanced training and experience in allergy, asthma and other immunologic diseases. The Academy is dedicated to the advancement of the knowledge and practice of allergy, asthma and immunology for optimal patient care. Most members of the AAAAI are board-certified allergist/immunologists. A select group of the membership are elected as Fellows and carry the title FAAAAI. The organization, headquartered in Milwaukee, Wisconsin, hosts a website for patients and healthcare professionals that includes a physician referral directory for patients. Mission The AAAAI is dedicated to the advancement of the knowledge and practice of allergy, asthma, and immunology for optimal patient care. History The American Academy of Allergy, Asthma, and Immunology (AAAAI) dates back t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allergic
Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Symptoms may include red eyes, an itchy rash, sneezing, coughing, a runny nose, shortness of breath, or swelling. Note that food intolerances and food poisoning are separate conditions. Common allergens include pollen and certain foods. Metals and other substances may also cause such problems. Food, insect stings, and medications are common causes of severe reactions. Their development is due to both genetic and environmental factors. The underlying mechanism involves immunoglobulin E antibodies (IgE), part of the body's immune system, binding to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine. Diagnosis is typical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on Scratch hardness, scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German , a term from the 19th century that came from the Latin word for Lime (material), lime, (genitive ) with the suffix ''-ite'' used to name minerals. It is thus a Doublet (linguistics), doublet of the word ''wikt:chalk, chalk''. When applied by archaeology, archaeologists and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
