Day
A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, noon, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.A collection of sequential days is organized into calendars as dates, almost always into weeks, months and years. A solar calendar organizes dates based on the Sun's annual cycle, giving consistent start dates for the four seasons from year to year. A lunar calendar organizes dates based on the Moon's lunar phase.
In common usage, a day starts at midnight, written as 00:00 or 12:00 am in 24- or 12-hour clocks, respectively. Because the time of midnight varies between locations, time zones are set up to facilitate the use of a uniform standard time. Other conventions are sometimes used, for example the Jewish religious calendar counts days from sunset to sunset, so the Jewish Sabbath begins at sundown on Friday. In astronomy, a day begins at noon so that observations throughout a single night are recorded as happening on the same day.
In specific applications, the definition of a day is slightly modified, such as in the SI day (exactly 86,400 seconds) used for computers and standards keeping, local mean time accounting of the Earth's natural fluctuation of a solar day, and stellar day and sidereal day (using the celestial sphere) used for astronomy. In most countries outside of the tropics, daylight saving time is practiced, and each year there will be one 23-hour civil day and one 25-hour civil day. Due to slight variations in the rotation of the Earth, there are rare times when a leap second will get inserted at the end of a UTC day, and so while almost all days have a duration of 86,400 seconds, there are these exceptional cases of a day with 86,401 seconds (in the half-century spanning 1972 through 2022, there have been a total of 27 leap seconds that have been inserted, so roughly once every other year). Provided by Wikipedia
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Alzheimer Disease Biomarkers in Clinical Practice: A Blood-Based Diagnostic Revolution by Madeline M. Paczynski, Gregory S. Day
Published 2022-12-01
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Assessment of the 3D geometrical effects on the DEMO divertor pumping efficiency by S. Varoutis, Yu. Igitkhanov, Chr. Day
Published 2019-05-01
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Anti-amyloid therapies for Alzheimer disease: finally, good news for patients by Vijay K. Ramanan, Gregory S. Day
Published 2023-06-01
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Kinetics and Mechanism of the Substitution of Ligand (Urea) of [Ti(ur)6]3+ by H2O and SCN¯ in Ethanol Solution by A. Kamkar, J.P. Day
Published 1987-06-01
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Joint US-UK Digital Preservation Workshop, Washington, D.C., May 7-9, 2006 by Michael Day, Helen Hockx-Yu
Published 2008-12-01
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Joint US-UK Digital Preservation Workshop, Washington, D.C., May 7-9, 2006 by Michael Day, Helen Hockx-Yu
Published 2008-12-01
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Understanding Disease Outcome Following Acquisition of Helicobacter pylori Infection during Childhood by Andrew S Day, Philip M Sherman
Published 1999-01-01
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Joint US-UK Digital Preservation Workshop, Washington, D.C., May 7-9, 2006 by Michael Day, Helen Hockx-Yu
Published 2008-12-01
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An Overview of International Guidelines Focusing on the Long-Term Management of Coeliac Disease by Sophie W. Hall, Andrew S. Day
Published 2020-06-01
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Satiating the Demand: Planning for Alternative Models of Regional Food Distribution by Lindsey Day-Farnsworth, Alfonso Morales
Published 2016-07-01
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The Role of TGF-β, Activin and Follistatin in Inflammatory Bowel Disease by Nasim Hatamzade Esfahani, Andrew S. Day
Published 2023-04-01
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The Genetics of Parkinson’s Disease and Implications for Clinical Practice by Jacob Oliver Day, Stephen Mullin
Published 2021-06-01
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The Utility of Fluorescence Recovery after Photobleaching (FRAP) to Study the Plasma Membrane by Charles A. Day, Minchul Kang
Published 2023-05-01
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Joint US-UK Digital Preservation Workshop, Washington, D.C., May 7-9, 2006 by Michael Day, Helen Hockx-Yu
Published 2008-12-01
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Joint US-UK Digital Preservation Workshop, Washington, D.C., May 7-9, 2006 by Michael Day, Helen Hockx-Yu
Published 2008-12-01
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Biodiversity of the Great Barrier Reef—how adequately is it protected? by Zoe T. Richards, Jon C. Day
Published 2018-05-01
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