Atomic mass constant: Difference between revisions

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m Reverted edits by 207.191.191.131 (talk) to last version by Götz
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WP:CHECKWIKI error fix #97. No content between TOC and first headline per WP:TOC and WP:LEAD. This is an accessibility issue for users of screen readers. Do general fixes and cleanup if needed. - using AWB (10190)
 
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The '''Beverton–Holt model''' is a classic discrete-time [[population modeling|population model]] which gives the [[expected value|expected]] number ''n''<sub>&nbsp;''t''+1</sub> (or density) of individuals in generation ''t''&nbsp;+&nbsp;1 as a function of the number of individuals in the previous generation,
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: <math>n_{t+1} = \frac{R_0 n_t}{1+ n_t/M}. </math>
 
Here ''R''<sub>0</sub> is interpreted as the proliferation rate per generation and ''K''&nbsp;=&nbsp;(''R''<sub>0</sub>&nbsp;&minus;&nbsp;1)&nbsp;''M'' is the [[carrying capacity]] of the environment. The Beverton–Holt model was introduced in the context of [[fisheries management|fisheries]] by [[Ray Beverton|Beverton]] & [[Sidney Holt|Holt]] (1957). Subsequent work has derived the model under other assumptions such as [[competition (biology)|contest competition]] (Brännström & Sumpter 2005) or within-year resource limited competition (Geritz & Kisdi 2004). The Beverton–Holt model can be generalized to include [[scramble competition]] (see the [[Ricker model]], the [[Hassell model]] and the [[John Maynard Smith|Maynard Smith]]–Slatkin model). It is also possible to include a parameter reflecting the spatial clustering of individuals (see Brännström & Sumpter 2005).
 
Despite being nonlinear, the model can be solved explicitly, since it is in fact an inhomogeneous linear equation in 1/''n''.
The solution is
 
: <math>
n_t = \frac{K n_0}{n_0 + (K - n_0) R_0^{-t}}.
</math>
 
Because of this structure, the model can be considered as the discrete-time analogue of the continuous-time [[logistic equation]] for [[population growth]] introduced by [[Pierre Verhulst|Verhulst]]; for comparison, the logistic equation is
 
: <math>\frac{dN}{dt} = rN \left( 1 - \frac{N}{K} \right),</math>
 
and its solution is
 
: <math>
N(t) = \frac{K N(0)}{N(0) + (K - N(0)) e^{-rt}}.
</math>
 
==References==
 
* {{Citation
| last = Beverton
| first = R. J. H.
| author-link =
| last2 = Holt
| first2 = S. J.
| year = 1957
| title = On the Dynamics of Exploited Fish Populations
| edition =
| volume =
| series = Fishery Investigations Series II Volume XIX
| publication-place =
| place =
| publisher = Ministry of Agriculture, Fisheries and Food
| pages =
| page =
| id =
| isbn =
| doi =
| oclc =
| url =
| accessdate =
}}
 
* {{Citation
| last = Brännström
| first = Åke
| last2 = Sumpter
| first2 = David J. T.
| author-link =
| year = 2005
| title = The role of competition and clustering in population dynamics
| periodical = Proc. R. Soc. B
| series =
| publication-place =
| place =
| publisher =
| volume = 272
| issue = 1576
| pages = 2065–2072
| url = http://www.math.uu.se/~david/web/BrannstromSumpter05a.pdf
| doi = 10.1098/rspb.2005.3185
| oclc =
| accessdate =
| pmid = 16191618
| pmc = 1559893
}}
 
* {{Citation
| last = Geritz
| first = Stefan A. H.
| author-link =
| last2 = Kisdi
| first2 = Éva
| year = 2004
| title = On the mechanistic underpinning of discrete-time population models with complex dynamics
| periodical = J. Theor. Biol.
| series =
| publication-place =
| place =
| publisher =
| volume = 228
| issue = 2
| pages = 261–269
| url =
| doi = 10.1016/j.jtbi.2004.01.003
| oclc =
| accessdate =
| pmid = 15094020
}}
 
*{{Citation
| last = Ricker
| first = W. E.
| author-link = Bill Ricker
| year = 1954
| title = Stock and recruitment
| periodical = J. Fisheries Res. Board Can.
| series =
| publication-place =
| place =
| publisher =
| volume = 11
| issue =
| pages = 559–623
| url =
| issn =
| doi =
| oclc =
| accessdate =
}}
 
{{DEFAULTSORT:Beverton-Holt model}}
[[Category:Demography]]
[[Category:Biostatistics]]
[[Category:Fisheries science]]
[[Category:Stochastic processes]]

Latest revision as of 06:41, 16 May 2014

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