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Topic: Decay


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  Beta decay - Wikipedia, the free encyclopedia
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted.
decay is allowed energetically (and the proton is a part of a nucleus with electron shells), it is accompanied by the electron capture process, when an atomic electron is captured by a nucleus with emission of neutrino:
Historically, the study of beta decay provided the first physical evidence of the neutrino.
en.wikipedia.org /wiki/Beta_decay   (759 words)

  
 Radioactive decay - Wikipedia, the free encyclopedia
Decay is said to occur in the parent nucleus and produces a daughter nucleus.
The SI unit for measuring radioactive decay is the becquerel (Bq).
On the premise that radioactive decay is truly random (rather than merely chaotic), it has been used in hardware random-number generators and is an invaluable tool in estimating the absolute ages of geological materials and young organic matter.
en.wikipedia.org /wiki/Radioactive_decay   (1739 words)

  
 Tooth decay
Tooth decay, which is also called dental cavities or dental caries, is the destruction of the outer surface (enamel) of a tooth.
Decay results from the action of bacteria that live in plaque, which is a sticky, whitish film formed by a protein in saliva (mucin) and sugary substances in the mouth.
Tooth decay in pits and fissures may be differentiated from dark shadows in the crevices of the chewing surfaces by a dye that selectively stains parts of the tooth that have lost mineral content.
www.healthatoz.com /healthatoz/Atoz/ency/tooth_decay.jsp   (2242 words)

  
 Decay Heat in Nuclear Reactors
Some radioactive atoms will decay while the reactor is operating and the energy released by their decay will be removed from the core along with the heat produced by the fission process.
The amount of decay heat is very significant; a nuclear reactor operated at full power for 3 or 4 days prior to shut down has much higher decay heat generation than a reactor operated at low power for the same period.
Decay heat may decrease to about 2% of the pre-shutdown power level within the first hour after shutdown and to 1% within the first day.
www.ontronic-efi.com /decay_heat.htm   (2463 words)

  
 Radioactivity
Beta decay can be seen as the decay of one of the neutrons to a proton via the weak interaction.
Positrons are emitted with the same kind of energy spectrum as electrons in negative beta decay because of the emission of the neutrino.
Because either a neutrino or an antineutrino is emitted as well, there is a spectrum of energies for the electron or positron, depending upon what fraction of the reaction energy Q is carried by the massive particle.
hyperphysics.phy-astr.gsu.edu /hbase/nuclear/beta.html   (364 words)

  
 Theory: Decays
decays, all the produced particles are new objects that were not present before the decay.
Decays can happen only if all conservation laws can be obeyed.
Nuclear stability and radioactive decays can all be explained from the same set of conservation laws and underlying interaction types as those for isolated particles.
www2.slac.stanford.edu /vvc/theory/decays.html   (507 words)

  
 Theory: Radioactive Decay
It emerges from a weak decay process in which one of the neutrons inside an atom decays to produce a proton, the beta electron and an anti-electron-type neutrino.
It is produced as a step in a radioactive decay chain when a massive nucleus produced by fission relaxes from the excited state in which it first formed towards its lowest energy or ground-state configuration.
Alpha decay is also a type of fission, common because the alpha particle is a particularly low energy arrangement of two protons and two neutrons.
www2.slac.stanford.edu /vvc/theory/nuclearstability.html   (694 words)

  
 Beta Decay   (Site not responding. Last check: 2007-11-06)
I'm going to illustrate how radioactive decay works with the help of an isotope table applet, which should now be open in a separate window.
H metamorphoses into helium 3, it also gives off an electron--which has hardly any mass, and is endowed with a negative charge that exactly cancels one proton.
This process is known as beta decay, and the electron is called a beta particle in this context.
www.colorado.edu /physics/2000/isotopes/radioactive_decay.html   (262 words)

  
 Forest Pathology - Wood Decay
Wood decay is a deterioration of wood by primarily enzymatic activities of microorganisms.
It is usually used to refer to decays that primarily develop in the stem rather than in the roots and butt.
Here we use the term stem decay for all diseases where the primary symptom is decay of stem wood, largely because 'heart rot' is thought by some some to imply that decay is restricted to heartwood, which is frequently not the case.
www.forestpathology.org /decay.html   (3079 words)

  
 Halflife   (Site not responding. Last check: 2007-11-06)
The halflife is the amount of time it takes for half of the atoms in a sample to decay.
In the top picture, you'll see the atoms change color as they decay; the lower picture is a graph showing the number of atoms of each type versus time.
Notice how the decays are fast and furious at the beginning and slow down over time; you can see this both from the color changes in the top window and from the graph.
www.colorado.edu /physics/2000/isotopes/radioactive_decay3.html   (300 words)

  
 What is tooth decay?
The formation of tooth decay ("cavities") can be a significant problem for some individuals, either as children or adults.
In short, tooth decay is a location on a tooth where so much of the tooth's mineral content as been dissolved away that a defect (a hole or a "cavity") has formed.
Yes, teeth do have nerves in their centers and this tissue is soft, but the surface of a tooth (where tooth decay begins) is formed from types of tissues that are very high in mineral content.
www.animated-teeth.com /tooth_decay/t1_tooth_decay_cavities.htm   (745 words)

  
 Wood Decay Fungi, Bora Care Fungus Control
Decay will occur in untreated wood in direct contact with ground, cement or concrete, or exposed to a source of moisture such as rain seepage, plumbing leaks or condensation.
The presence of molds and stains, however, is a sign that conditions are favorable for decay fungi and a preventative treatment may be necessary.
When controlling decay fungi, treatment with Boracare should not be considered as a replacement for moisture control.
www.pestproducts.com /decayfungi.htm   (1371 words)

  
 Decay
Decay starts after a tooth is colonised by bacteria.
Filling materials are subject to leaking, allowing bacteria and their nutrients to re-enter, so it is possible to have a reoccurrence of the original decay or new decay.
Even where decay occurs under an old filling and the filling needs to be removed, it appears sensible to use HealOzone prior to restoring the tooth with conventional materials.
www.wharfdental.com /decay.htm   (364 words)

  
 EPA - Decay Chains (EPA's Radiation Protection Program: Understanding Radiation)   (Site not responding. Last check: 2007-11-06)
As radioactive decay progresses, the concentration of the original radionuclides decreases, while the concentration of their decay products increases and then decreases as they undergo transformation.
The importance of understanding decay chains is illustrated by the ingrowth of radon-222 during decay of uranium-238.
Radon decay emits alpha particles, the radiation that presents the greatest hazard to lung tissue.
www.epa.gov /radiation/understand/chain.htm   (781 words)

  
 Plate Rotation   (Site not responding. Last check: 2007-11-06)
Elements such as uranium, thorium, and plutonium are observed to emit particles and thereby undergo radioactive decay.
Radioactive decay is an exponential process such that half of the parent element will decay to the daughter element in a set amount of time (known as the half-life).
The primary elements in the decay series are shown with their relative abundances as individual bars, such that initially the parent element has an abundance of 1e10 atoms.
www.mines.utah.edu /~ggapps/radiation/radiation.html   (425 words)

  
 decay
They observed, in every case they investigated, that the rate of decay of radioactive matter was proportional to the amount present.
There are several quantitative aspects of radioactivity that are important for managing nuclear waste materials, including how much radioactivity a given substance emits, how concentrated the substance is in its surrounding medium, how dangerous its emissions are to human and other biological populations, and how long the substance goes on being radioactive.
Some nuclides decay to stable substances sufficiently fast (half-lives ranging from fractions of a second to a matter of days) that they are not a serious threat to the environment.
www.math.jmu.edu /~liu/decay.htm   (1137 words)

  
 Tooth Decay
Dental caries (tooth decay) ranks among the most prevalent chronic diseases worldwide, and the consequences of tooth decay include pain, suffering, infection, tooth loss, and the subsequent need for costly restorative treatment.
Tooth Decay is a break down of the tooth's enamel over a period of time.
Tooth Decay can be caused by many factors such as: Mothers Diet during pregnancy, Diet of the Child, Baby Bottle Mouth Syndrome, Dental Hygiene, and Heredity just to name a few.
teething-teeth.com /Tooth_Decay.html   (890 words)

  
 Radiometric Dating
The non-radiogenic stable isotopes, osmium-186 or -188, are used as the denominator in the ratios on the three-isotope plots.
Electron capture decay of light atoms--those having the fewest electrons--can be very slightly affected by extremely high pressures or certain chemical bonds, so as to change their half-lives by a fraction of a percent.
During the change, or decay, energy is released either in the form of light or energetic particles.
www.asa3.org /ASA/resources/Wiens.html   (16626 words)

  
 Applet: Decay   (Site not responding. Last check: 2007-11-06)
Shown (red dots) is a large number of identical atomic nuclei, each obeying the same decay law.
Now select the half life time of the nuclei with the slider, press the strat button, and watch them decay away as a function of time (displayed in the upper right corner).
Shown also is a histogram (in green) of the number of nuclei remaining at a given time.
lectureonline.cl.msu.edu /~mmp/applist/decay/decay.htm   (66 words)

  
 What are the Radioactive Byproducts of Depleted Uranium (Uranium-238)?   (Site not responding. Last check: 2007-11-06)
When uranium ore is extracted from the earth, most of the uranium is removed from the crushed rock during the milling process, but the radioactive decay products are left in the tailings.
Thus 85 percent of the radioactivity of the original ore is discarded in the mill tailings.
The horizontal bar beside the name of each decay product indicates the "half life" of that particular substance, measured on a logarithmic scale (each half-inch to the right represents multiplication by a factor of one thousand).
www.ccnr.org /decay_U238.html   (403 words)

  
 The Decay of c-decay
Setterfield's religious motivation is now clear, and if his revised figure for the age of the universe just happens to match the now-discredited chronology of Bishop Ussher (about 6,000 years), it would probably not be a coincidence.
As Setterfield states, "The basic postulate of this article is that light has slowed down exponentially since the time of creation," making it clear that he intends to show not only a decay in the value of c, but an exponential decay.
After supplying all of 41 selected data points representing measurements of c since 1675, Setterfield claims to have found the one and only curve that adequately fits these particular points and that must represent the behavior of the value of c.
www.talkorigins.org /faqs/c-decay.html   (2038 words)

  
 Tooth Decay
Tooth decay is the disease that is not life threatening and the good news is that it is preventable!
An area of decay may take as long as 6-8 years or as short as 6 months to dissolve the outer layer (enamel) of the tooth.
There is a fundamental need for more evidence of appropriate rigor and quality before the use of ozone can be accepted into mainstream primary dental care or can be considered a viable alternative to current methods for the management and treatment of dental caries.
www.dentalgentlecare.com /tooth_decay.htm   (1150 words)

  
 Decay
Decay, dk, aethereal FORGE and their logos are © and ™ 1996-2002 æthereal FORGE.
Any information found on Vodun belief on this site, or anywhere else in the Decay world, is a representation of the faith as it applies to the Decay world.
It is not intended to provide an accurate description of real Vodun, nor does it necessarily portray the beliefs of the creators of Decay.
dk.terminal.org /index2.shtml   (267 words)

  
 SatEvo Page   (Site not responding. Last check: 2007-11-06)
For objects nearing decay, it generates sets of orbital elements for each revolution.
For the final days of some interesting decayers, I post predicted elsets to SeeSat-L and on my Decay Watch page..
Up-to-date orbital elements (elsets) are important for accurate predictions during the final weeks, days and hours of a satellite's life; a small percentage change in the drag experienced by such an object can make it run early or late by several minutes after only a few days.
www.wingar.demon.co.uk /satevo   (367 words)

  
 Short Primer on U238 Radioactive Decay   (Site not responding. Last check: 2007-11-06)
Atoms in a radioactive substance decay in a random fashion but at a characteristic rate.
The half-life is the time taken for half of the atoms of a radioactive substance to decay.
As it undergoes radioactive decay, a chain of products is formed as a result of one by-product itself decaying to another element, which in turn decays further until finally reaching an element that is stable.
www.atral.com /U2381.html   (308 words)

  
 Does phentermine decay teeth - phentermine buy phentermine phentermine 37 5mg cheap phentermine   (Site not responding. Last check: 2007-11-06)
does phentermine decay teeth infantry took up their position, some about the stockades, others 19 to be the same as that which is now called Gumisch-Kana--perhaps pay for the soldiers.
Why does phentermine decay teeth nor yet as a private soldier, but simply on the invitation of an old does phentermine decay teeth bitterest disappointments and sorrows.
Above it all, however, there soars, And now is your spirit ashamed to be at the service of your bowels, and does phentermine decay teeth lights as if they were oracles from which one did not dare to marched three stages, twenty parasangs in all, to Celaenae, a populous in half the time.
ment.freeyellow.com /phentermine/does-phentermine-decay-teeth   (577 words)

  
 www.myspace.com/decaydayton   (Site not responding. Last check: 2007-11-06)
Decay, a band based out of Dayton, Ohio (home to national acts Twelve Tribes, Guided by Voices and The Breeders)
Decay was selected from hundreds of talented bands to perform at The Ninth Annual Milwaukee Metal Fest.
Well known for their aggressive performance, Decay must be witnessed live to experience their magnetism, energy, intensity, and honest emotion that they convey through their music.
www.myspace.com /decaydayton   (699 words)

  
 Technorati Tag: Decay   (Site not responding. Last check: 2007-11-06)
Decay on eBay Find Decay items at low prices.
Buy Urban Decay Makeup at Sephora Free shipping over $75 at Sephora, find Urban Decay and 265 beauty brands.
Posts tagged Decay per day for the last 30 days.
www.technorati.com /tag/Decay   (368 words)

  
 C-decay - EvoWiki   (Site not responding. Last check: 2007-11-06)
Specifically: Light emitted from Point P at time T should get here more quickly than light emitted from Point P at a later time (T + 1), which in turn should get here more quickly than light emitted from Point P at a still later time (T + 2), and so on.
This effect should be plainly evident in observations of radioactive decay curves in supernovas, but in fact, all the radioactive decay curves yet observed exhibit no such effect.
As well, there are pulsars -- the astronomical equivalent of metronomes -- the fastest of which (PSR1937+21) emits signals at a rate of one every 1.5 milliseconds, or 640 Hertz.
wiki.cotch.net /index.php/C-decay   (616 words)

  
 NNN Nucleon Decay Workshop   (Site not responding. Last check: 2007-11-06)
To continue the fruitful discussions we had during the NNN99 workshop at Stony Brook, we are organizing a small 2-day NNN Nucleon decay working group meeting at UC Irvine (Feb. 25-26, 2000).
This workshop will be held on the UCI campus at the University Club (see Campus Map building 32).
In the meeting, we will continue discussions on various detector and technology options, and our future strategy/plan for producing a viable and compelling proposal for a large scale Nucleon Decay detector (see tentative agenda).
www.ps.uci.edu /~sobel/NNN/Workshop.html   (272 words)

  
 Flickr: Urban Decay
There are also rusted car and graffiti groups you might enjoy since we're not really looking for rusty cars or graffiti here.
There is even a new Rural Decay group for photos of decaying Barns, Silos, Farms..
Use the Urban Decay Colr Pickr to locate photos of a particular color.
www.flickr.com /groups/decay   (125 words)

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