taro (colocasiaesculental. schott) is a perennial root crop that belongs to araceace family. it is widely cultivated as a staple food in africa, asia and pacific islands. despite its importance, there is limited information on many aspects of the crop. in order to obtain data that can support improved and sustainable taro production, a field trial was conducted to study the effects of corm size...

aphids in unsprayed canola (brassica napus linnaeus) fields in isfahan province (central iran) were sampled for two growing seasons, 2011-2013. sampling unit was a whole plant and 20 plants were sampled weekly. in the laboratory, heat-extracting and sub-sampling techniques were used to estimate the density of aphids. to determine the relationship between population growth rate of the aphids and...

1. Second derivatives of the population growth rate measure the curvature of its response to demographic, physiological or environmental parameters. The second derivatives quantify the response of sensitivity results to perturbations, provide a classification of types of selection and provide one way to calculate sensitivities of the stochastic growth rate. 2. Using matrix calculus, we derive t...

The study reported here assessed residents' perception of small, fast-growing coastal community on issues of quality of life, conservation, and growth. Data for the study were collected from an on-site survey in Aransas County, Texas from 2006 to 2007. Results show that the residents are concerned about preserving their natural resources, maintaining a small town atmosphere in their community, ...

This paper builds a small-open-economy, non-scale-growth model with negative population growth and investigates the relationship between trade patterns and per capita consumption growth. Under free trade, if the population growth rate is negative and its absolute value is small, the home country becomes an agricultural country. Then, the long-run growth rate of per capita consumption is positiv...

The rapid population growth of many African cities has important implications for population health, yet little is known about factors contributing to increasing population, such as the fertility of internal migrants. We examine whether in-migrants to Kinshasa have different fertility patterns than lifetime Kinshasa residents, and identify characteristics of migrants that may explain difference...

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 .