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Intercalary
Intercalation may refer to: *Intercalation (chemistry), insertion of a molecule (or ion) into layered solids such as graphite * Intercalation (timekeeping), insertion of a leap day, week or month into some calendar years to make the calendar follow the seasons *Intercalation (university administration), period when a student is officially given time off from studying for an academic degree * Intercalation (geology), a special form of interbedding, where two distinct depositional environments in close spatial proximity migrate back and forth across the border zone *Intercalary chapter, a chapter in a novel that does not further the plot. See also frame story (sometimes called intercalation). * In biology: ** Intercalary segment, an appendage-less segment in the segmental composition of the heads of insects and Myriapoda **Intercalation (biochemistry), process discovered by Leonard Lerman by which certain drugs and mutagens insert themselves between base pairs of DNA **Intercalated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalation (timekeeping)
Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months. Solar calendars The solar or tropical year does not have a whole number of days (it is about 365.24 days), but a calendar year must have a whole number of days. The most common way to reconcile the two is to vary the number of days in the calendar year. In solar calendars, this is done by adding to a common year of 365 days, an extra day ("leap day" or "intercalary day") about every four years, causing a leap year to have 366 days ( Julian, Gregorian and Indian national calendars). The Decree of Canopus, which was issued by the pharaoh Ptolemy III Euergetes of Ancient Egypt in 239 BCE, decreed a solar leap day system; an Egyptian leap year was not adopted until 25 BC, when the Roman Emperor Augustus successfully instituted a re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalary Chapter
An intercalary chapter (also called an inner chapter, inserted chapter, or interchapter) is a chapter in a novel or novella that is relevant to the theme, but does not involve the main characters or further the plot. Intercalary chapters often take the form of vignettes that offer a broader or alternative perspective to the experiences of the main character. They can also be used to provide social and historical background that can't be easily interwoven into the narrative chapters. Examples The following novels make use of intercalary chapters: * ''American Gods'' by Neil Gaiman * ''Cry, the Beloved Country'' by Alan Paton * ''The Grapes of Wrath'', by John Steinbeck * ''The Left Hand of Darkness'' by Ursula K. Le Guin * '' Moby-Dick; or, The Whale'' by Herman Melville * ''Tom Jones'' by Henry Fielding * ''War and Peace'' by Leo Tolstoy * ''The Ministry for the Future'' by Kim Stanley Robinson Kim Stanley Robinson (born March 23, 1952) is an American writer of science fiction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod Head Problem
The (pan)arthropod head problem is a long-standing zoological dispute concerning the segmental composition of the heads of the various arthropod groups, and how they are evolutionarily related to each other. While the dispute has historically centered on the exact make-up of the insect head, it has been widened to include other living arthropods such as chelicerates, myriapods, crustaceans; and fossil forms, such as the many arthropods known from exceptionally preserved Cambrian faunas. While the topic has classically been based on insect embryology, in recent years a great deal of developmental molecular data has become available. Dozens of more or less distinct solutions to the problem, dating back to at least 1897, have been published, including several in the 2000s. The arthropod head problem is popularly known as the endless dispute, the title of a famous paper on the subject by Jacob G. Rempel in 1975, referring to its seemingly intractable nature. Although some progress ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalation (chemistry)
In chemistry, intercalation is the reversible inclusion or insertion of a molecule (or ion) into layered materials with layered structures. Examples are found in graphite and transition metal dichalcogenides. : Examples Graphite One famous intercalation host is graphite, which intercalates potassium as a guest. Intercalation expands the van der Waals gap between sheets, which requires energy. Usually this energy is supplied by charge transfer between the guest and the host solid, i.e., redox. Two potassium graphite compounds are KC8 and KC24. Carbon fluorides (e.g., (CF)x and (C4F)) are prepared by reaction of fluorine with graphitic carbon. The color is greyish, white, or yellow. The bond between the carbon and fluorine atoms is covalent, thus fluorine is not intercalated. Such materials have been considered as a cathode in various lithium batteries. Treating graphite with strong acids in the presence of oxidizing agents causes the graphite to oxidise. Graphite bisulfate, 24 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalation (university Administration)
Intercalation, also known as intermission or interruption, in the context of university administration, is a period when a student is allowed to officially take time away from studying for an academic degree. When a university A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States ... or similar institution allows a student to intercalate, it is usually for one of the following reasons: * on medical or compassionate grounds, so that the student can take a break from his or her studies and return later.Guidance from the University of Hull on compas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalation (geology)
In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. For example, sedimentary rocks may be interbedded if there were sea level variations in their sedimentary depositional environment. Intercalation is a special case of interbedding where a layer is variably inserted into an already existing sequence; or where two separate depositional environments in close spatial proximity migrate alternately across the contact. While interbedding has layers that are horizontally flat (or aligned with the angle of the entire stratum), intercalated rock on the other hand has slanted layers that streak through each other (even when it aligns with the stratum). For example intercalated conglomerate and sandstone looks like ripples of different material networked through each other somewhat off the horizontal, as the beds are deposited in a gradient. This is likely due to differing fluvial conditions a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Story
A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (construction), a building term known as light frame construction * Framer, a carpenter who assembles major structural elements in constructing a building * A-frame, a basic structure designed to bear a load in a lightweight economical manner ** A-frame house, a house following the same principle * Door frame or window frame, fixed structures to which the hinges of doors or windows are attached *Frame and panel, a method of woodworking *Space frame, a method of construction using lightweight or light materials *Timber framing, a method of building for creating framed structures of heavy timber or willow wood In vehicles * Frame (aircraft), structural rings in an aircraft fuselage * Frame (nautical), the skeleton of a boat * Bicycle frame, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalation (biochemistry)
In biochemistry, intercalation is the insertion of molecules between the planar bases of deoxyribonucleic acid (DNA). This process is used as a method for analyzing DNA and it is also the basis of certain kinds of poisoning. There are several ways molecules (in this case, also known as ''ligand (biochemistry), ligands'') can interact with DNA. Ligands may interact with DNA by Covalent_bond, covalently binding, electrostatically binding, or intercalating. Intercalation occurs when ligands of an appropriate size and chemical nature fit themselves in between base pairs of DNA. These ligands are mostly polycyclic, aromatic, and planar, and therefore often make good nucleic acid staining (biology), stains. Intensively studied DNA intercalators include berberine, ethidium bromide, proflavine, daunomycin, doxorubicin, and thalidomide. DNA intercalators are used in chemotherapy, chemotherapeutic treatment to inhibit DNA replication in rapidly growing cancer cells. Examples include doxor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalated Cells Of The Amygdala
The intercalated cells of the amygdala (ITC or ICC) are a group of GABAergic neurons situated between the basolateral and central nuclei of the amygdala that play a significant role in inhibitory control over the amygdala. They play important regulatory roles in amygdala-dependent emotional processing, and their dysfunction has been shown to impair fear extinction, fear generalization, and social behavior. In rodents, ITCs are organized into distinct clusters that wrap the basolateral amygdala (BLA). Each cluster is unique in connectivity, intrinsic properties, and function. Function ITC cells are thought to play a role as the "off" switch for the amygdala, inhibiting the amygdala's central nucleus output neurons and its basolateral nucleus neurons. The ITC clusters work together to activate either "fear promoting" or "fear extinction" pathways within the amygdala. Some researchers speculate that ITC cells could serve as a substrate for the expression and storage of extinction memo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collecting Duct
The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis. The collecting duct system is the last part of nephron and participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin (antidiuretic hormone). There are several components of the collecting duct system, including the connecting tubules, cortical collecting ducts, and medullary collecting ducts. Structure Segments The segments of the system are as follows: Connecting tubule With respect to the renal corpuscle, the connecting tubule (CNT, or junctional tubule, or arcuate renal tubule) is the most proximal part of the collecting duct system. It is adjacent to the distal convoluted tubule, the most distal segment of the renal tubule. Connecting tubules from several adjacent nephrons merge to form cortical collecting tubules, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intercalated Disc
Intercalated discs or lines of Eberth are microscopic identifying features of cardiac muscle. Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional syncytium. By contrast, skeletal muscle consists of multinucleated muscle fibers and exhibits no intercalated discs. Intercalated discs support synchronized contraction of cardiac tissue. They occur at the Z line of the sarcomere and can be visualized easily when observing a longitudinal section of the tissue. Structure Intercalated discs are complex structures that connect adjacent cardiac muscle cells. The three types of cell junction recognised as making up an intercalated disc are desmosomes, fascia adherens junctions, and gap junctions. * Fascia adherens are anchoring sites for actin, and connect to the closest sarcomere. * Desmosomes prevent separation during contraction by binding intermediate filaments, anchoring the cell membrane to the inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
