Population fluctuation

The recent report of wave-like patterns of bacteria and water soluble carbon associated with wheat roots (58) which were not strongly correlated with each other or with lateral root formation pose a challenge for models. So do the reports of highly dynamic and erratic population fluctuations of individual pseudomonad clones on sugar beet roots (59). 

Bark beetle populations fluctuate through time and periodically pose a threat (decrease) to available forest resources resulting in a subsequent loss of revenue. A number... 

From a historical point of view one can expect periodic outbreaks as a result of population fluctuations. Hence, one can expect that the amount of mortality taking place in our forests, will be similar to the past and we would expect it to continue at... 

Population fluctuation has not always been common in species. Natural populations... 

Pheromone traps that mimic pests own signals are useful tools for monitoring insect appearances. They can help you determine when the first pests arrive and when the population dwindles. The directions supplied with specific commercial traps explain how to interpret the population fluctuations. See Phero-... 

Insects produce chemicals called sex pheromones to help them locate suitable mates. Some male insects are able to detect female pheromones at extremely low concentrations from as far away as 5 miles. Professional pest scouts take advantage of this ability by using synthetic pheromones, placed in special traps, to attract and capture the males of a species. By monitoring daily capture rates to detect population fluctuations, they can adsise growers if and when control measures are necesary. ... 

Traps covered with sticky coating strategically placed among your plants will capture sufficient numbers of certain pests to control their damage. Originally used to monitor pest population fluctuations, sticky boards work well as controls when concentrated in small areas. 

The relevant correlation function in our case is related to population fluctuations. Without loss of generality, one assumes the existence of a reaction coordinate q such that reactants, labeled a, are defined by the region q < q and products, labeled b, are defined by the region q > q. Following the discussion in Ref. 5, one defines the characteristic function of reactants (products) (q) (0/>(<7)) as... 

A recently developed model to explain this intermittency observed in the population fluctuation assumes a bistable potential whose two minima are the HDL and LDL [12]. By definition, these two forms differ by their specific volumes HDL has relatively lower specific volume than LDL. Now, natural total volume fluctuations of the system at ambient pressure modify the underlying bistable potential as a larger volume stabilizes the LDL state and vice versa. If one assumes that volume fluctuation is periodic in nature, then the effective potential of the system also modulates periodically with the same frequency as volume fluctuation. 

Figure 22.4. (a) Temporal variation of the numbers of 4- and 5-coordinated species in supercooled water at T = 250 K. Note the strong anti-correlated fluctuations between N cif) nd Nsc t) and intermittency in the fluctuations of bofli species at T = 250 K. (b) Corresponding power spectrum of flie population fluctuation time correlation function. Note the l/f dependence of flie intensity which confirms the presence of intermittency at T = 250 K. Adapted with permission from J. Phys. Chem. B, (Lett.), 113 (2009), 2221-2224. Copyright (2009) American Chemical Society. 

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