The Effect of Antinotches on Domain Wall Mobility in Single Crystal Ferroelectric Nanowires

Changes in domain wall mobility, caused by the presence of antinotches in single crystal BaTiO3 nanowires, have been investigated. While antinotches appeared to cause a slight broadening in the distribution of switching events, observed as a function of applied electric field (inferred from capacitance-voltage measurements), the effect was often subtle. Greater clarity of information was obtained from Rayleigh analysis of the capacitance variation with ac field amplitude. Here the magnitude of the domain wall mobility parameter (R) associated with irreversible wall movements was found to be reduced by the presence of antinotches - an effect which became more noticeable on heating toward the Curie temperature. The reduction in this domain wall mobility was contrasted with the noticeable enhancement found previously in ferroelectric wires with notches. Finite element modeling of the electric field, developed in the nanowires during switching, revealed regions of increased and decreased local field at the center of the notch and antinotch structures, respectively; the absolute magnitude of field enhancement in the notch centers was considerably greater than the field reduction in the center of the antinotches and this was commensurate with the manner in, and degree to, which domain wall mobility appeared to be affected. We therefore conclude that the main mechanism by which morphology alters the irreversible component of the domain wall mobility in ferroelectric wire structures is via the manner in which morphological variations alter the spatial distribution of the electric field.

Spatial Mobility, Workers and Jobs: Perspectives from the Northern Ireland Experience

Spatial mobility, workers and jobs: perspectives from the Northern Ireland experience,Regional Studies. How best to address local concentrations of worklessness is a key question for labour market, economic developmentand social inclusion policy. Historically, initiatives in Northern Ireland have focused on moving ‘jobs to workers’, butin changed political circumstances there is now greater emphasis on encouraging the movement of ‘workers to jobs’. A review of the Northern Ireland experience in the context of broader consideration of the geography and socio-institutional structure of local labour markets sheds light on the difficulties and successes in implementing both approaches. It is concluded that both have a role to play because labour market space is simultaneously ‘segmented’ and ‘seamless

Escalators, Elevators and Travelators: The Occupational Mobility of Migrants to South-East England

In a meritocratic society it is assumed that the chance of achieving occupational mobility (OM) is not strongly influenced by one's starting position in terms of class or ethnicity. This paper seeks to explain the drivers of the high levels of OM achieved by one ethnically defined group: the Scots. Educational attainment is shown to be particularly important. A second level of interest is the changing role of internal migrants to a global city in the face of increased international skilled immigration. We investigate whether there is any evidence that the OM of internal migrants is being hindered as a result. The evidence points instead to immobile local labour being more disadvantaged occupationally than mobile labour from peripheral regions of the state.

Like a rolling stone: the mobility of maerl (Corallinaceae) and the neutrality of the associated assemblages

Beds of nonattached coralline algae (maerl or rhodoliths) are widespread and considered relatively species rich. This habitat is generally found in areas where there is chronic physical disturbance such that maerl thalli are frequently moved. Little is known, however, about how natural disturbance regimes affect the species associated with maerl. This study compared the richness, animal abundance, and algal biomass of maerl-associated species over a two-year period in a wave-disturbed bed and a sheltered maerl bed. Changes in associated species over time were assessed for departures from a neutral model in which the dissimilarity between samples reflects random sampling from a common species pool. Algal biomass and species richness at the wave-exposed site and on stabilized maerl at the sheltered site were reduced at times of higher wind speeds. The changes in species richness were not distinguishable from a neutral model, implying that algal species were added at random to the assemblage as the level of disturbance lessened. Results for animal species were more mixed. Although mobile species were less abundant during windy periods at the exposed site, both neutral and non-neutral patterns were evident in the assemblages. Artificial stabilization of maerl had inconsistent effects on the richness of animals but always resulted in more attached algal species. While the results show that the response of a community to disturbance can be neutral, the domain of neutral changes in communities may be relatively small. Alongside non-neutral responses to natural disturbance, artificial stabilization always resulted in an assemblage that was more distinct than would be expected under random sampling from a common pool. Community responses to stabilization treatments did not consistently follow the predictions of the dynamic equilibrium model, the intermediate disturbance model, or a facilitation model. These inconsistencies may reflect site-specific variation in both the disturbance regime and the adjacent habitats that provide source populations for many of the species found associated with maerl.

Imperial Migrations. Colonial Communities and Diaspora in the Portuguese World

This volume explores the role and history of migration and diaspora within the Portuguese empire, investigating what role colonial communities and diaspora have had in shaping the Portuguese empire and its heritage. The book consists of twelve case studies which look at topics such as Portuguese migration to Africa, the Ismaili and the Swiss presence in Mozambique, the Goanese in East Africa, the Chinese in Brazil, and the history of the African presence in Portugal.

Spatial Mobility Intentions, the Labour Market and Incapacity Benefit Claimants Evidence from Northern Ireland

The paper analyses the work-related spatial mobility intentions of incapacity benefit (IB) claimants in Northern Ireland using a new survey dataset. Greater understanding of the prospective mobility of benefit claimants contributes to debates about employability, inclusion in the labour market and arguments about spatial mismatch. The analysis finds that IB claimants are not markedly less mobile than other population groups; that mobility is shaped by age, level of qualification, illness type, ability to drive and motivation; and that geography is important in several ways. The paper concludes by arguing that limited spatial mobility is a good indicator of disadvantage and that spatial mobility should be placed nearer the centre of the design and delivery of labour market policy