3 resultados para migration processes
Resumo:
Abstract:
This paper combines demographic ageing and retirement lifestyles with rural in-migration processes and suggests the emergence of a specific rural form of gated community; namely, park homes. All year round or permanent (as opposed to seasonal) residential mobile homes (resembling detached bungalows in design and appearance) are commonly referred to as 'park homes'. With a growing proportion of the UK population aged 65 and over, combined with increasing longevity, meeting the residential preferences and lifestyle aspirations of an ageing population is potentially 'big business' for the private sector. Park home living, with their resident age restrictions (normally 50 years and over), is increasingly marketed as a retirement option in rural and coastal locations of the UK. However, many areas are often remote with declining populations and limited community services. Operators have sought to tap into retiree aspirations for a 'place in the country' and 'sell' the concept of park home living as a specific form of housing, community and lifestyle. Park homes are frequently marketed as a means to release equity from the sale of a large family home to fund a retirement lifestyle and as friendly communities of like-minded people, always willing to lend support or provide assistance if required. The physical and social composition of such sites represent a form of rural gated community. This paper seeks to identify the rural planning issues which emerge from such developments and asks: who are moving to park home sites and why? do park homes provide those who otherwise could not afford a 'place in the country' the option of rural living? does park home living live-up to residents' expectations of the rural idyll or retirement lifestyle? do they give rise to issues of gentrification and geriatrification of the countryside? what are the prospects for residents to 'age in place'? might ageing residents become financially trapped in such developments giving rise to park ghettoization? what are the associated challenges for rural policy-makers and public service providers?
Resumo:
After sudden ionization of a large molecule, the positive charge can migrate throughout the system on a sub-femtosecond time scale, purely guided by electronic coherences. The possibility to actively explore the role of the electron dynamics in the photo-chemistry of bio-relevant molecules is of fundamental interest for understanding, and perhaps ultimately controlling, the processes leading to damage, mutation and, more generally, to the alteration of the biological functions of the macromolecule. Attosecond laser sources can provide the extreme time resolution required to follow this ultrafast charge flow. In this review we will present recent advances in attosecond molecular science: after a brief description of the results obtained for small molecules, recent experimental and theoretical findings on charge migration in bio-relevant molecules will be discussed.
Resumo:
Understanding the population structure and patterns of gene flow within species is of fundamental importance to the study of evolution. In the fields of population and evolutionary genetics, measures of genetic differentiation are commonly used to gather this information. One potential caveat is that these measures assume gene flow to be symmetric. However, asymmetric gene flow is common in nature, especially in systems driven by physical processes such as wind or water currents. As information about levels of asymmetric gene flow among populations is essential for the correct interpretation of the distribution of contemporary genetic diversity within species, this should not be overlooked. To obtain information on asymmetric migration patterns from genetic data, complex models based on maximum-likelihood or Bayesian approaches generally need to be employed, often at great computational cost. Here, a new simpler and more efficient approach for understanding gene flow patterns is presented. This approach allows the estimation of directional components of genetic divergence between pairs of populations at low computational effort, using any of the classical or modern measures of genetic differentiation. These directional measures of genetic differentiation can further be used to calculate directional relative migration and to detect asymmetries in gene flow patterns. This can be done in a user-friendly web application called divMigrate-online introduced in this study. Using simulated data sets with known gene flow regimes, we demonstrate that the method is capable of resolving complex migration patterns under a range of study designs.