wiktionarypar period periodic TOCright Period may mean a full stop a punctuation in American English. Period from Greek or periodic may also refer to Science Orbital period , a concept in astronomy Period gene , a gene in Drosophila involved in regulating circadian rhythm Period geology , a subdivision of geologic time Periodic function and periodical, a function that repeats its values in regular intervals Periodic group in group butts Periodic table , a chart which lists all currently known chemical elements Period periodic table , a horizontal row of the periodic table Periodic acid , an oxoacid of iodine Period physics , the time taken for one full oscillation, it is the reciprocal of frequency Orbit dynamics Period of orbit Periodization Period of time Language and literature Period punctuation , a punctuation mark indicating the end of a sentence or phrase, specifically, a dot. Periodic sentence , a sentence that is not grammatically complete until its end The final book in Dennis Cooper George Miles cycle Dennis Cooper s George Miles cycle of novels History Pisano periodPeriod piece describes creative works set in a particular era Medical Menstruation , a phase of the menstrual cycle in which the uterine lining is shed Mathematics The period of a periodic function Periods ring the Ring mathematics ring of numbers which can be expressed as integrals of algebraic differential forms over algebraically defined domains Academics Period school , a class period in schools Music Instruments Period music , a concept in musical composition Sports Ice hockey Periods and overtime Periods in ice hockey , intervals into which a match is divided Other meanings Periodicity disambiguation Periodicity , the quality of occurring at regular intervals or periods See also Periodization ... Periodo id Periode it Periodo lb Period lt Periodas nl Periode ja no Periode nds Periood pl Okres pt Per odo ru simple Period sk Peri da fi Jakso sv Period uk ... more details
In finance , in particular with reference to Bond finance bonds and Swap finance swaps , a stub period is a period of time over which interest accrues which is not equal to the usual interval between Coupon bond bond coupon . These normally occur because the interval between coupons does not fit neatly into the period that the bond was issued for, thus sometimes a bond s final or first coupon period may be adjusted to make the bond start and mature on the desired dates. References Unreferenced date April 2009 finance stub Category Finance ... more details
Unreferenced stub auto yes date December 2009 A waiting period is a period of time which one must wait disambiguation wait in order for a specific action to occur, after that action is request ed or mandate d. The term is commonly used in reference to gun control in the United States , where some U.S. states required a person to wait for a set number of days after buying or reserving a firearm at a dealer before actually taking Possession law possession of it. Waiting periods are also used for new insurance , particularly health insurance and flood insurance . Incidents which occur during this time are not claimable. The term may also refer to the time between the making of a claim and the payment of it, also called the elimination period . In business finance , a waiting period or quiet period is the time in which a company making an IPO must be silent about it, so as not to watered stock inflate the value of the stock artificially . It is also called the cooling off period . Other things potentially subject to waiting periods include divorce and merger proceedings. See also Waiting period Six Day War Queue disambiguation DEFAULTSORT Waiting Period Category Lawsuits Category Time Law term stub ... more details
Context date October 2009 Quiet period or waiting period has historically meant , a quiet period of time extended from the time a company files a SEC filing registration statement with the United States Securities and Exchange Commission SEC until SEC staff declared the registration statement effective. During that period, the United States securities law federal securities laws limited what information a company and related parties can release to the public. ref http www.sec.gov answers quiet.htm ref Under the rules of the Securities Act of 1933 , as modified June 29, 2005, electronic communications, including electronic road shows and information located on or hyperlink ed to an issuer s website are also governed. The rules changes of June 29, 2005 also included various changes which liberalize permitted offering activity and communications to allow more information for certain qualifying organizations. In business finance , a waiting period or quiet period is the time in which a company making an IPO must be silent about it, so as not to watered stock inflate the value of the stock artificially . It is also called the cooling off period . References refs See also Waiting period Category Corporations law Category Time finance stub ... more details
unreferenced date November 2011 A sunrise period is a period of time after the launch of a new top level domain or second level domain during which owners of trademarks may register a domain name containing the owned mark. Numerous domains have launched or plan to launch with a sunrise period, including .info info , .mobi mobi , .pk pk , and .eu eu . The World Intellectual Property Organization provided assistance to info administrator Afilias during its sunrise period. Category Domain name system Compu domain stub de Sunrise Period no Sunrise periode vi Giai o n M t tr i m c ... more details
during a student s free period Some schools have an extended lunch period and that could be used as a free period as well. Lunch periods in high school could be up to 60 minutes long. A free period in a college is a timeperiod that a student is not enrolled in a class. During the free period, students ... , but some make it a time for socialization , eating , sleeping , running errands, and many ... services of the college . References Reflist DEFAULTSORT Free Period Category School terminology ... more details
Unreferenced date March 2009 Payback period in capital budgeting refers to the period of time required ... which returned 500 per year would have a two year payback period. The time value of money is not taken into account. Payback period intuitively measures how long something takes to pay for itself ... operating costs. Although primarily a financial term, the concept of a payback period is occasionally extended to other uses, such as energy payback period the period of time over which the energy ... period is widely used because of its ease of use despite the recognized limitations described below ... fluorescent light bulb may be described as having a payback period of a certain number of years ... not be standardized or widely used. Payback period as a tool of analysis is often used because it is easy ... alone tool to compare an investment to doing nothing, payback period has no explicit criteria for decision making except, perhaps, that the payback period should be less than infinity . The payback period is considered a method of analysis with serious limitations and qualifications for its use, because it does not account for the time value of money , risk , financing or other important considerations, such as the opportunity cost . Whilst the time value of money can be rectified by applying ... are net present value and internal rate of return . An implicit assumption in the use of payback period is that returns to the investment continue after the payback period. Payback period does not specify ... to calculate the payback period, except the simple and unrealistic case of the initial cash ... period an algorithm that is easlily applied in spreadsheets is needed. The typical algorithm reduces .... Note There actually IS a formula for calculating payback period, which is Payback Period Year .... The modified payback period algorithm may be applied then. First, the sum of all of the cash outflows is calculated. Then the cumulative positive cash flows are determined for each period. The modified ... more details
The retention period of a document is an aspect of records management . It represents the period of time a document should be kept or retained . At the termination of the retention period, the document is usually destroyed. The term is generally used by accountants and tax professionals whose occupation involves dealing with legal documents that only need to remain in existence for a certain amount of time. The retention period varies for different types of records. For example, business incorporation documents have a permanent retention period meaning that they should be retained and never be destroyed , but receipts for tax deductible purchases by an individual taxpayer usually have a three year retention period and can often be safely discarded after that point. The length of the retention period is based on the likelihood that the document will be needed at some point in the future. Records that will serve no further purpose as determined by the length of their retention period are destroyed for space issues, usually by paper shredder s. Retention requirements are also established for a variety of electronic records in industry specific legislation such as the Sarbanes Oxley Act and regulatory bodies such as the Federal Energy Regulatory Commission in the United States . ref http www.csoonline.com read 070106 record retention.html The Seven Deadly Sins of Records Retention CSOonline.com Bot generated title ref References references tax stub Category Taxation Category Legal documents Category Data management de Aufbewahrungsfrist ... more details
disamb term refractory period Refractory period physiology , the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following excitation in the areas of biology, physiology, and cardiology. Refractory period sex Refractory period sexology , the recovery phase after orgasm during which it is physiologically impossible for an individual to have additional orgasms. Psychological refractory period , the delay in response to the second of two closely spaced psychological stimuli. The period of weeks or even months following a series of seizures during which seizures cannot be induced when referring to epilepsy , known as the Postictal state . disambig Category Neuroscience bg de Refrakt rphase Sexualit t es Periodo refractario lt Refrakcinis laikotarpis nl Refractaire periode ru ... more details
Harrison s Principles of Internal Medicine ed.17th ref See also Incubation period , the time between infection and the appearance of symptoms References Reflist colwidth 50em DEFAULTSORT Window Period ...In medicine, the window period for a test designed to detect a specific disease particularly infectious disease is the time between first infection and when the test can reliably detect that infection. In antibody based testing, the window period is dependent on the time taken for seroconversion . The window period is important to epidemiology and safe sex strategies, and in blood donation blood and organ donation , because during this time, an infected person or animal cannot be detected as infected ... strategies combine testing with a waiting period longer than the test s window period. Examples HIV AIDS http aids.gov hiv aids basics prevention your hiv status testing window period U.S. Government site www.AIDS.gov informs The timeframe between when you are exposed to HIV to the time you test positive for HIV antibodies can be up to 3 6 months. This period of time is called a window period for HIV testing. On average, you may need to wait 2 to 8 weeks from the time of possible exposure to get ... window period Government site www.AIDS.gov, Testing Window Period ref HIV test Window period Related ... HIV being present results during the window period, an interval of three weeks to six months between the time of HIV infection and the production of measurable antibodies to HIV seroconversion. Most ... a six month window is extremely rare with modern antibody testing. During the window period ... test. Antiretroviral therapy during the window period can delay the formation of antibodies and extend the window period beyond 12 months. This was not the case with patients that underwent ... window period of 6 months. Antibody tests may also yield false negative results in patients with X ... the window period or equivalence zone of Hepatitis B , both serological markers HBsAg Hepatitis B ... more details
Period piece is a phrase that is used to describe creative works. Usage Setting In the performing arts , a period piece is a work set in a particular era. This informal term covers all countries, all periods and all genre s. It may be as long and general as the Middle Ages medieval era or as limited as one decade&mdash the Roaring Twenties , for example. Work from the past Period piece can also describe a work that was famous in a past era but less so today for example, one might describe a production of a drama by one of Shakespeare s contemporaries as an interesting period piece but would be less likely to describe a production of Hamlet as such. Or date July 2009 Period piece is contrasted with classic classic piece , or something with timeless or lasting broad readership. Recent work Period piece can also be used Subjectivity subjective ly, such as when applied to contemporary or recent works which have not been tested by time, since it is guessing how future generations will view the work. For example Harold Bloom in The Western Canon 1994 labels those works not included in his list of 20th century literature as being mostly period pieces see Appendix header for The Chaotic Age . Since these works are still being widely read Harry Potter for example , it is impossible to know if they will become regarded as classics in the future or simply fade away into mostly unread period ... Period Dramas.com &ndash a costume drama movie database based around a historical timeline. http www.justperiodmovies.com Period Movies listings of period piece films from various historical eras. http enchantedserenityperiodfilms.blogspot.com Enchanted Serenity of Period Films fansite that profiles period piece films including news of upcoming films http www.recycledmoviecostumes.com ... periodmoviesbox.blogspot.com Period Movies Box blog dedicated to period movies news and reviews DEFAULTSORT Period Piece Category Performing arts Category Historical fiction Category Period pieces ... more details
Wiktionary A grace period is a time past the deadline for an obligation during which a late penalty that would have been imposed is waived. Grace periods, which can range from a number of minutes to a number of days or longer, depending on the context, can apply in various situations, including arrival at a Employment job , paying a Bill payment bill , for meeting government or legal requirement, or in many other situations. In law , a grace period is a timeperiod during which a particular rule exceptionally does not apply, or only partially applies. For the grace period in patent patent law , see novelty patent . Types of grace periods Some companies and organizations do not view one who fulfills an obligation within a grace period any differently. In these situations, a subject who is past due, but who meets the obligation within the grace period receives equal treatment and no penalty or negative reputation. Other clients may receive a partial, less severe penalty. For example, many ... date. However, the utility service provider will wait a longer timeperiod before Turn off notice cutting off service . Some companies may suspend certain privileges during a grace period. For example ... information. A timeperiod after a payment due date within which the fee can be paid without penalty ... home3.americanexpress.com corp consumerinfo grace.asp An extensive tutorial on the types of Grace Period .... For example, people who habitually are on time for their obligations, but due to occasional unforeseen ... period and maintain their reputation for timeliness. However, habitual procrastinate procrastinators may come to view the grace period as the actual deadline, and if, due to unforeseen circumstances ... the pros and cons of Grace Period ref Credit cards In personal finance , a grace period is the period ... off notice Grandfather clause Sunset clause References reflist DEFAULTSORT Grace Period Credit cards Category Personal financial problems Category Credit card terminology pl Grace period ru ... more details
Multiple issues unreferenced September 2011 lead rewrite February 2011 notability February 2011 A landrush period is the time during which domain name s are available for registration, usually to a closed group, to entities that do not own a trademark in the name they wish to register, for example generic terms like loan or car , and thus would not qualify for registration during the sunrise period . Orders may or may not be treated on a first come first served basis. This period follows the sunrise period just after the launch of a new top level domain or second level domain during which, for example, owners of trademark s may register a domain name containing the owned mark, but a landrush period precedes a period of general availability, when any qualifying entity can register any name on a first come first served basis. Unfortunately, those excluded from the closed group are minorities and women. These groups are always prevented from participating during the landrush period which is only open to white males. Also, there has been debate on whether Jewish white males qualify. That has yet to be decided. ref stayed at a Holiday Inn Express ref references Category Domain name system Compu domain stub ... more details
In epidemiology , Period prevalence is the proportion of the population with a given disease or condition over a specific period of time. It could describe how many people in a population had a cold over the cold season in 2006, for example. It is expressed as a percentage of the population and can be described by the following formula Period prevalence ratio Number of cases that occurred in a given period Number of people in the population during this period The relationship between incidence rate , point prevalence ratio and period prevalence ratio is easily explicated via an analogy with photography. Point prevalence is akin to a flashlit photograph what is happening at this instant frozen in time. Period prevalence is analogous to a long exposure seconds, rather than an instant photograph the number of events recorded in the photo whilst the camera shutter was open. In a movie each frame records an instant point prevalence by looking from frame to frame one notices new events incident events and can relate the number of such events to a period number of frames incidence rate. See also Point prevalence For example.... In our street of 1000 people on 1st Jan 2011, 200 had a car. Once they have a car nobody changes their car. Each year 365 people buy a car and 265 people get rid of one. The point prevalence of cars in our street as at 1st Jan 2011 is 20 The incidence of car buying is 1 per day. The period prevalence of car ownership in 2011 is 565 or 56.5 the number of people who, at some point in the year own a car The point prevalence on 1st Jan 2012 is 30 because 300 people now own a car. References cite book author Gerstman, B.B. year 2003 title Epidemiology Kept Simple 2nd ed. location Hoboken NJ publisher Wiley Liss Category Epidemiology med stub Medical research studies ... more details
Lunar geo time The Copernican Period in the lunar geologic timescale runs from approximately 1.1 billion years ago to the present day. The base of the Copernican period is defined by impact craters that possess bright optically immature ray system s. The Copernicus lunar crater crater Copernicus is a prominent example of rayed crater, but it does not mark the base of the Copernican period. No mare basalts are known to have erupted within the Copernican period, and for this reason, the Moon s internal geologic activity is thought to have effectively ceased by this time. Definition The base of the Copernican period is defined based on the recognition that freshly excavated materials on the lunar surface are generally bright and that they become darker over time as a result of space weathering processes. Operationally, this period was originally defined as the time at which impact craters lost their bright ray system s. This definition, however, has recently been subjected to some criticism as some crater rays are bright for compositional reasons that are unrelated to the amount of space weathering they have incurred. In particular, if the ejecta from a crater formed in the highlands which is composed of bright anorthositic materials is deposited on the low albedo mare, it will remain bright even after being space weathered. Timeline Lunar Geological Timescale Relationship to Earth s geologic time scale Its Earth equivalents are the Neoproterozoic era of the Proterozoic eon and the whole of the Phanerozoic eon. So, while animal life bloomed on Earth, the Moon s geologic activity was coming to an end. References cite web url http www.psrd.hawaii.edu Sept04 LunarRays.html title Lunar Crater Rays Point to a New Lunar Time Scale last Martel, L. M. V. publisher Planetary Science Research Discoveries date 2004 09 28 Category Lunar geologic periods Moon stub br Kopernisian ca Copernic da Copernician es Per odo Copernicano fr Copernicien it Copernicano nl Copernicum tijdperk ru ... more details
In economics , a base period or reference period is a point in time used as a reference point for comparison with other periods. ref name uslabor cite web url http www.bls.gov bls glossary.htm title BLS Information date February 28, 2008 work Glossary publisher U.S. Bureau of Labor Statistics Division of Information Services accessdate 2009 05 05 ref ref name investopedia cite web url http www.investopedia.com terms b baseperiod.asp title Base Period publisher Investopedia accessdate 2009 05 05 ref It is generally used as a benchmark for measuring financial or economic data. ref name investw cite web url http www.investorwords.com 429 base period.html title base period publisher investorwords.com accessdate 2009 05 05 ref Base periods typically provide a point of reference for economic studies, consumer demand, and unemployment benefit claims. See also Bureau of Labor Statistics Economic indicator Gross domestic product Consumer price index References Reflist External links http www.bls.gov bls glossary.htm Base period in glossary , U.S. Bureau of Labor Statistics Division of Information Services http www.investopedia.com terms b baseperiod.asp Base Period , Investopedia Category Economics terminology Category Labor terms econ stub ... more details
about the music album Orbital Period album Unreferenced date December 2009 The orbital period is the time ... as observed from Earth returns to the same illumination phase. The synodic period is the time ... linear order. The synodic period differs from the sidereal period due to the Earth s orbiting around the Sun. The draconitic period , or draconic period , is the time that elapses between two passages ... period to differ from the sidereal period. The anomalistic period is the time that elapses between ... period because the object s semimajor axis typically advances slowly. Also, the Earth s tropical period or simply its year is the time that elapses between two alignments of its axis of rotation ... Orbital Period Category Astrodynamics Category Celestial mechanics Category Time in astronomy als Siderische ... further qualification in astronomy this refers to the sidereal period of an astronomical object, which ... around the Sun or other celestial objects The sidereal period is the temporal cycle that it takes ... orbital period. The synodic period is the temporal interval that it takes for an object to reappear ... the ecliptic from the southern to the northern hemisphere. This period differes from the sidereal period because both the orbital plane of the object and the plane of the ecliptic precess with respect ... has a slightly shorter interval than the solar orbit sidereal period because the inclined axis and equatorial ... needed date January 2011 class wikitable sortable Sidereal Period julian year astronomy a Synodic Period a Synodic Period day d Solar rotation Solar surface ... of a planet s natural satellite moon , the synodic period usually means the Sun synodic period. That is to say, the time it takes the moon to complete its illumination phases, completing the solar phases ... Deimos synodic period is 1.2648 days, 0.18 longer than Deimos sidereal period of 1.2624 d. cn date November 2011 The Earth synodic period can also be calculated, but it varies with the planet ... more details
For the first menstrual cycle , or first menstrual bleeding Menarche File Fairbanks house dedham.jpg thumb right Fairbanks House Dedham, Massachusetts Fairbanks House , built in 1636, is the oldest surviving timber frame house in America First Period is a designation in colonial United States American architecture and design. It refers to the time period of approximately 1626 through 1725 . Its successor is the American colonial architecture Colonial Georgian Period. Characteristics Among other characteristics, First Period houses have a steeply pitched roof a slightly asymmetrical plan and a central chimney. The first period house is distinguished from later houses by its exposed often decorated or chamfered frame in the interior. Some early windows in modest houses may have had no glazing, but the standard first period window, until at least 1700, was the diamond paned casement. No example of this type of window survives in situ all current examples date to at the very earliest the late 19th century. Multiple light, sliding sash windows started to appear around 1700, and by about 1750 had supplanted the earlier type. See also American colonial architecture List of the oldest buildings in America External links http www.salemweb.com guide arch first.shtml Salem Massachusetts First Period gives a description of this period as well as others Category American architectural styles Category Vernacular architecture arch style stub ... more details
A return period also known as a recurrence interval is an estimate of the interval of time between events like an earthquake , flood or discharge hydrology river discharge flow of a certain intensity or size. It is a statistical measurement denoting the average recurrence interval over an extended period of time, and is usually required for risk analysis i.e. whether a project should be allowed to go ... an event of a certain return period with its associated intensity . Equation Recurrence ... of the surge, and similarly for other events. Return period as expected frequency The theoretical return period is the inverse of the probability that the event will be probability of exceedance ... statement the expected number of 100 year events in an n year period is n 100, in the sense of expected value . Similarly, the expected time until another 100 year event is 100 years, and if in a given year or years the event does not occur, the expected time until it occurs remains 100 years, with this 100 years resetting each time. It does not mean that 100 year floods will happen regularly , every 100 years, despite the connotations of the name return period in any given 100 year period, a 100 ... be computed as below. Note also that the estimated return period below is a statistic it is computed ... event. Probability distribution In a given period of n years, the probability of a given ... in a period of n years. math binom n r times p r times 1 p n r math Example Given that the return period of an event is 50 years, math P 1 over 50 0.02 math . So the probability that such an event occurs ... 10 times 0.02 times 0.834 math math approx 0.167 , math Risk analysis Return period is also useful ... design expectations the return period is useful in calculating the risk of the structure with respect to a given storm return period when given the design life expectation. This is the likelihood of at least ..., return periods, and confidence intervals DEFAULTSORT Return Period Category Hydrology Category ... more details
A benefit period is a length of time during which a benefit is paid. This may be a government benefit such as the British Housing Benefit ref cite web url http www.dwp.gov.uk advisers rr2 working 06.asp title RR2 A guide to Housing Benefit and Council Tax Benefit work UK Department for Work and Pensions accessdate 2009 02 25 ref , or a healthcare benefit system such as the American Medicare United States Medicare , or payment from an insurance policy such as a Payment protection insurance ref cite web url http antinsurance.co.uk benefit period.html title What s a benefit period? work ANT insurance accessdate 2009 02 25 ref which covers mortgage or other commitments after accident, illness or redundancy. It may also be known as the Payment period. A related terms is Benefit week ref cite web url http www.opsi.gov.uk si si2007 uksi 20071331 en 1 title The Social Security, Housing Benefit and Council Tax Benefit Miscellaneous Amendments Regulations 2007 work UK Office of Public Sector Information quote ...where the claimant is not entitled to housing benefit in the benefit week immediately following the date of his claim but the relevant authority is of the opinion that unless there is a change of circumstances he will be entitled to housing benefit for a period beginning not later than the thirteenth benefit week following the date on which the claim is made, the relevant authority ... week of that period of entitlement and award benefit accordingly. accessdate 2009 02 25 ref used in calculation ... of the United States healthcare system Medicare United States Medicare , a Benefit period begins the day a beneficiary is admitted to a hospital or skilled nursing facility SNF . The benefit period ends ... days in a row. If a beneficiary is readmitted into a hospital or SNF after one benefit period has ended, a new benefit period begins. Benefit year or season A Benefit sports Benefit year or season ref ... 2009 02 25 ref is a period during which a sports person is granted the benefit of various activities ... more details
pm or 11 15 am, as the case may be. Typically, 2 15 pm is the start time for Question Period Monday through Thursday, with Question Period starting at 11 15 on Fridays. On Wednesday, Question Period ...for the Canadian television program Question Period TV series Question Period , known officially as Oral ... purpose of Question Period is to seek information from the Government and to call it to account ... rules to govern Question Period occurred in April 1964 , and subsequent rule changes have been ... precedents when a new Point of Order or questions arises about practices during Question Period. For a detailed ... . Current practice Question Period lasts 45 minutes pursuant to Standing Order 30 5 , ref ... Question Period, the Speaker recognizes the Leader of the Opposition Canada Leader of the Opposition ..., the Liberal Party of Canada Liberal Party . Throughout the remainder of Question Period, Members of officially ... and Parliamentary Secretaries do not ask questions. Rules Question Period has a reputation for being ... the heckling, Question Period is actually tightly regulated. Parties are only allowed ... after the specified time has elapsed. The parties may negotiate a maximum time limit for each question ... true when the minister addressed is not actually present in the House during Question Period, and arguably ... , Question Period is bilingual. Questions may be posed in either English language English or French ... Period, on many news networks, as well as the CPAC TV network Cable Public Affairs Channel CPAC . Transcripts of Question Period are published in both official languages in the Canadian Hansard , as with any ... also conducts its own form of question period. Question Period in Canada is similar to the Prime ... s Questions in the British House of Commons Question Hour in the Lok Sabha Question Time in the Parliament of Australia Question Time Question and Answer Session in Hong Kong Question Period television Question Period , a Canadian political news series on CTV television network CTV which takes its name ... more details
Soviet Russia Post communist period Russia and other former Soviet states, after 1991 See also List of time periods including paleoecological, paleogeological, archaeological, physical and cosmological groups, etcetera. For histories of certain time periods see Category History by period . For histories ...see also List of time periods Whether one can precisely define a time window as High Middle Ages or Early Middle Ages the title evokes an image and expectations in the reader of certain sets of characteristics the essential essence of such labeling a communications tool from one mind to another. Nonetheless, periods have a generally accepted meaning within all disciplines even though a given community of scholarship applies different criteria to their meaning of the same general term used in other disciplines consequently squabbles about exact date ranges are mostly shrugged aside a s counter productive&mdash in large part this is an extension of the recognition that one region develops at a different ..., Quaternary period recently replaced by Neogene period Historical periods Bronze Age Classical antiquity ... Rome 509 BC 476 Period of the Three Kingdoms China, 220 280 Dark Age Europe, 4th century 900 Middle ... , Europe, 793 1066 Nara period Japan, 709 795 Period of Five Dynasties and Ten Kingdoms China, 907 960 Sengoku period Japan, 1478 1605 Early Modern Europe, 14th century 18th century The Renaissance .... Elizabethan period United Kingdom, 1558 1603 The Protestant Reformation Europe, 16th century The Age ... Napoleonic Era , 1799 1815 Victorian era United Kingdom, 1837 1901 Edwardian period United Kingdom, 1901 1910 Meiji era Japan, 1868 1912 World War I Much of Earth, 1914 1918 Interwar period Earth ... by city . For histories of other topics, see Category History by topic Category History by period Category History Category History by region Unreferenced date December 2006 DEFAULTSORT History By Period Category History by period Category Social sciences Category Humanities ... more details
File Sigmoid curve for an autocatalytical reaction.jpg 230px thumb right A sigmoid curve of an autocatalytic reaction. When t 0 to 50, the rate of reaction is low. Thereafter, the reaction accelerates, until almost all reactants have been consumed. At that point, the reaction rate tapers off. An induction period in chemical kinetics is an initial slow stage of a chemical reaction after the induction period, the reaction accelerates. ref GoldBookRef title induction period file I03019 ref Ignoring induction periods can lead to runaway reaction s. In some catalytic reactions, a pre catalyst needs to undergo a transformation to form the active catalyst, before the catalyst can take effect. Time is required for this transformation, hence the induction period. For example, with Wilkinson s catalyst , one triphenylphosphine ligand must dissociate to give the coordinatively unsaturated 14 electron species which can participate in the catalytic cycle File RevisedCatCycle.png 300px thumb left Wilkinson s catalyst requires activation before it can participate in the catalytic cycle br clear left Similarly, for an autocatalytic reaction , where one of the reaction products catalyzes the reaction itself, the rate of reaction is low initially until sufficient products have formed to catalyze the reaction. Reactions generally accelerate when heat is applied. Where a reaction is exothermic , the rate of the reaction may initially be low. As the reaction proceeds, heat is generated, and the rate of reaction increases. This type of reaction often exhibits an induction period as well. Grignard reagents are notorious for having induction periods. This is usually due to two reasons Firstly, the thin film of oxide on the magnesium reagent must be removed before the bulk magnesium can react. Secondly, Grignard reactions, while exothermic, are typically conducted at low temperature for better selectivity. For these two reasons, Grignard reactions often can have a long induction period, fol ... more details
off the Tyrrhenian coast of Italy. These interchanges led to a period of intensive borrowing in which ... the orientalizing period also accompanied the invention of the Greek alphabet, based on the earlier ... was marked by floral and animal motifs it was the first time discernibly Greek religious and mythological ... important center of this period, Corinth , the orientalizing influence started earlier, though the tendency ... way to thorough Hellenization of imported features in the Archaic period in Greece Archaic Period that followed. In the West, Etruscan civilization passed through an Orientalizing period approximately at the same time, ca. 730 580 BCE. From the mid sixth century, the growth of Achaemenid power in the eastern ... The Orientalizing Period in the Etruscan World University of Pennsylvania Museum of Archaeology ... period uk ... more details
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