Distance learning universities usually afford their students the flexibility to advance their studies at their own pace. This can lead to a considerable fluctuation of student populations within a program’s courses, possibly affecting the academic viability of a program as well as the related required resources. Providing a method that estimates this population could be of substantial help to u...

Dairy cow systems based on grassland utilization are characterized by a variation of harvested forage quality from 1 year to another and a fluctuation of grass availability and quality during the pasture season. Consequently, the energy supplied by the diet – i.e., concentrates plus hay or silage in winter and grazing in summer, may not always match animal requirements. A modelling approach ena...

Field Studies were carried out on the management of potato mite Polyphagotarsonemus latus, through chemical pesticides; Confidence (Imadachlorpid), Diafinthiuran (Diafinthiuran) and Actera (Thiamethoxam) on seasonal plots of Potato crop at Gilgit Baltistan region during 2014. The pesticides were applied at their recommended doses, when the nymph of mite starts appearing and seen easily feeding ...

We examined long-term time series of stock status for the temperate tunas Pacific bluefin and albacore in the north Pacific, and characterized temporal changes in the stock status of both species through comparison with tropical tunas in the Western and Central Pacific. The temperate tunas appear to have historically experienced considerable fluctuation in stock status over a long period of tim...

Causes of cyclic fluctuations in abundance (population cycles) of some small-mammal populations remain poorly understood despite 6 decades of research and .20 hypotheses. Population cycles are demographic processes and cannot be fully explained without considering demographic mechanisms that underlie cyclic fluctuations in abundance. From simulation studies, we have recently shown that phase-re...

Experiments in recent years have vividly demonstrated that gene expression can be highly stochastic. How protein concentration fluctuations affect the growth rate of a population of cells is, however, a wide-open question. We present a mathematical model that makes it possible to quantify the effect of protein concentration fluctuations on the growth rate of a population of genetically identica...

pistachio psylla, agonoscena pistaciae burckhardt & lauterer, is a key pest of pistachio trees in the pistachio-producing regions throughout iran. the investigation of biology of pests under the field condition in each region is the first step that must be taken in developing an integrated pest management program. the seasonal fluctuations of eggs, nymphs and adults of pistachio psylla were inv...

Vulnerable wildlife populations can face a suite of anthropogenic activities that may threaten their persistence. However, human-mediated disturbances are likely to be coincident with natural disturbances that also influence a population. This synergism is often neglected in population projection models. Here I evaluate the effects of natural (rainfall fluctuation) and human disturbances (habit...

The position of propagating population fronts fluctuates because of the discreteness of the individuals and stochastic character of processes of birth, death, and migration. Here we consider a Markov model of a population front propagating into a metastable state, and focus on the weak noise limit. For typical, small fluctuations the front motion is diffusive, and we calculate the front diffusi...