Effect of pair interactions on transition probabilities between inactive and active states: achieving collective behaviour via pair interactions in social insects

To understand the evolution of well-organized social behaviour, we must first understand the mechanism by which collective behaviour establishes. In this study, the mechanisms of collective behaviour in a colony of social insects were studied in terms of the transition probability between active and inactive states, which is linked to mutual interactions. The active and inactive states of the social insects were statistically extracted from the velocity profiles. From the duration distributions of the two states, we found that 1) the durations of active and inactive states follow an exponential law, and 2) pair interactions increase the transition probability from inactive to active states. The regulation of the transition probability by paired interactions suggests that such interactions control the populations of active and inactive workers in the colony.

Change in construction: a critical perspective

Change within the construction sector has been a central concern of governments and a select few private-sector clients for a considerable time. The discourse of change emanating from organizations concerned with reform in the construction sector reflects these ongoing concerns for change in the sector. The underlying assumptions of the content of change and appropriate change mechanisms in the UK are critically examined and challenged. In particular, the limitations of measurement and best practice are explored. The allegiance to approaches based on measurement and best practice is acontextual, unreflective and insufficient in providing wholly reliable explanations for the relationship between practice and performance. Claims for the use of measurement and best practice by the reform movement must therefore be understood to have limitations and their use approached with caution. The emphasis on best practice is also understood to direct attention away from understanding the legitimacy of current practice and change within the UK construction sector. An agenda for change in the UK construction sector will need to engage with and be more reflective of current managerial practice and past change initiatives. Contextual approaches such as structuration theory offer a way in which to underpin a research framework that could support the reform movement in setting such an agenda.

Who adopts Green Revolution (GR) technology in Ghana?

Sub-Saharan Africa in general and Ghana in particular, missed out on the Green revolution. Efforts are being made to re-introduce the revolution, and this calls for more socio-economic research into the factors influencing the adoption of new technologies, hence, this study. The study sought to find out how socio-economic factors contribute to adoption of Green revolution technology in Ghana. The method of analysis involved a maximum likelihood estimation of a probit model. The proportion of Green revolution inputs was found to be greater for the following: households whose heads had formal education, households with higher levels of non-farm income, credit and labor supply as well as those living in urban centers. It is recommended that levels of complementary inputs such as credit, extension services and infrastructure are increased. Also, households must be encouraged to form farmer-groups as an important source of farm labor. Furthermore, the fundamental problems of illiteracy must be addressed through increasing the levels of formal and non-formal education; and the gap between the rural and urban centers must be bridged through infrastructural and rural development. However, care must be taken to ensure that small-scale farmers are not marginalized, in terms of access to these complementary inputs that go with effective adoption of new technology. With these policies well implemented, Ghana can catch up with her Asian counterparts in this re-introduction of the revolution.

"Ever-growing Amman", Jordan: Urban expansion, social polarisation and contemporary urban planning issues

Amman the primate capital city of the Hashemite Kingdom of Jordan currently has a population in excess of 2 million, but in 1924 it consisted of little more than a collection of dwellings and some 2000-3000 inhabitants. The present paper sets out to document and explain the phenomenal expansion of "ever-growing Amman". The physical geography of the urban region and the early growth of the city are considered at the outset and this leads directly to consideration of the highly polarised social structuring that characterises contemporary Amman. In doing this, original data derived from the recent Greater Amman Municipality's Geographical Information System are presented. In this respect, the essential modernity of the city is exemplified. The employment and industrial bases of the city and a range of pressing contemporary issues are then considered, including transport and congestion, the provision of urban water under conditions of water stress and privatisation, and urban and regional development planning for the city. The paper concludes by emphasizing the growing regional and international geopolitical salience of the city of Amman at the start of the 21st century. (C) 2008 Elsevier Ltd. All rights reserved.

Small towns as 'sub-poles' in English rural development: Investigating rural-urban linkages using sub-regional social accounting matrices

This paper uses spatial economic data from four small English towns to measure the strength of economic integration between town and hinterland and to estimate the magnitude of town-hinterland spill-over effects. Following estimation of local integration indicators and inter-locale flows, sub-regional social accounting matrices (SAMs) are developed to estimate the strength of local employment and output multipliers for various economic sectors. The potential value of a town as a 'sub-pole' in local economic development is shown to be dependent on structural differences in the local economy, such as the particular mix of firms within towns. Although the multipliers are generally small, indicating a low level of local linkages, some sectors, particularly financial services and banking, show consistently higher multipliers for both output and employment. (c) 2007 Elsevier Ltd. All rights reserved.

Social networks, migration, and care in Tanzania

This paper explores the impacts of the HIV/AIDS epidemic on children and families in northern Tanzania using the concept of social resilience.1 The study is based on the findings of childfocused research with street children and children and families from HIV/AIDS-affected households. The paper illustrates the coping strategies that children and young people, and parents and caregivers adopt at the household level. In particular, it examines how the burden of care affects different generations of women and highlights their resilience, together with the importance of social networks and the fluidity of movement between rural and urban areas. The research suggests that migrating to urban areas to seek a living in the informal sector represents a survival strategy adopted by some children and young people orphaned by AIDS when their families and communities are unable or unwilling to support them. The paper concludes by exploring parents’, caregivers’, children’s, and young people’s views on the forms of social support that would promote their resilience and thereby help to mitigate the impacts of the epidemic at the household level.

Steering without Circe : attending to reinforcing loops in social systems

Relating system dynamics to the broad systems movement, the key notion is that reinforcing loops deserve no less attention than balancing loops. Three specific propositions follow. First, since reinforcing loops arise in surprising places, investigations of complex systems must consider their possible existence and potential impact. Second, because the strength of reinforcing loops can be misinferred - we include an example from the field of servomechanisms - computer simulation can be essential. Be it project management, corporate growth or inventory oscillation, simulation helps to assess consequences of reinforcing loops and options for interventions. Third, in social systems the consequences of reinforcing loops are not inevitable. Examples concerning globalization illustrate how difficult it might be to challenge such assumptions. However, system dynamics and ideas from contemporary social theory help to show that even the most complex social systems are, in principle, subject to human influence. In conclusion, by employing these ideas, by attending to reinforcing as well as balancing loops, system dynamics work can improve the understanding of social systems and illuminate our choices when attempting to steer them.