The development of stochastic demography has largely been based on age structured populations, although other types of demographic structure, especially permanent and dynamic heterogeneity, are likely common in natural populations. The combination of stochasticity and demographic structure is a challenge for analyses of population dynamics and extinction risk, because the population structure w...

We consider the finite generation-time effect in virus evolution models, introducing differential equations with delay. The suggested approach more adequately describes the evolution in case of growing populations than the popular models of population genetics, especially for the viruses with large number of offspring during one life cycle. Now the mean fitness, as a coefficient for exponential...

The physician workforce has steadily grown faster than the U.S. population over the past 30 years, context that is often absent in conversations anticipating physician scarcity. Policy makers addressing future physician shortages should also direct resources to ensure specialty and geographic distribution that best serves population health .

Human capital raises rural incomes, but this effect is swamped by higher returns to human capital in urban markets. This leads to “brain drain” from rural areas. Populations grow more rapidly in rural counties that have a diversified employment base. Farm population grows faster (or declines more slowly) in counties with relatively high farm income, and nonfarm populations grow faster in counti...

Concerns about population growth historically revolved around the notion that there may be insufficient arable land, minerals or energy to meet the needs of an exponentially increasing population. Today they are compounded by fears that as wealth increases, so would consumption of natural resources, and that new technologies would enable further exploitation of these resources. Absent empirical...

the cotton bollworm, helicoverpa armigera (hübner), is one of the important polyphagous pests causing serious loss to many economically important crops in iran. the goal of this experiment was to study the age-stage, two-sex life table of h. armigera on different bean cultivars including white kidney bean (cultivars daneshkadeh, pak, and shokufa), red kidney bean (cultivars akhtar, naz, and say...

in the turfgrass industry, the need for salinity tolerant turfgrasses is increasing because of the increased use of saline and non-potable water. greenhouse container experiments were conducted to determine the relative salinity tolerance and growth responses of eleven native populations of tall fescue (festuca arundinacea schrub) (tf), including: semirom, mashhad, sanandaj, yasuj, yazd abad, d...

reducing nitrogen status of floriculture plants is an effective tactic in pest management by decreasing host plant quality. life table parameters and population growth rate of aphis craccivora(hemiptera: aphidiae), as well as cosmetic and qualitative parameters losses associated with aphid infestation were evaluated in relation to n fertilization levels on gomphrena globosa, under greenhouse co...

the life table parameters of macrosiphum rosae l. (hemiptera: aphididae) on five vermicompost-tea (tea-compost) concentrations (20, 40, 60, 80 and 100%) and control treatment (0%) on rosa hybrida l. were determined under laboratory conditions. there were significant differences among pre-imaginal period and adult longevity of the aphid on the five teacompost concentrations. the highest mortalit...