Urbanisation and Structural Transformation

This paper presents new evidence on urbanization using sub-county data for the United States from 1880-2000 and municipality data for Brazil from 1970-2000. We show that the two central stylized features of population growth for cities - Gibrat's Law and a stable population distribution - are strongly rejected when both rural and urban areas are considered. Population growth exhibits a U-shaped relationship with initial population density, and only becomes uncorrelated with initial population density at the high densities found in predominantly urban areas. We provide evidence that the explanation for these patterns lies in different employment growth dynamics in the agricultural and non-agricultural sectors and the process of structural transformation away from the agricultural sector.urbanisation, economic development, urban population, rural population

In brief: sharing the fruits of trade.

One of CEP's core research themes is the impact of trade openness on countries, firms, regions, communities and sectors.Two recent studies confirm the gains from opening up trade - but recognise that addressing the uneven outcomes of globalisation is as big a challenge as pursuing liberalisation in the face of entrenched interests.

Resistance of Trichoplusia ni to Bacillus thuringiensis Toxin Cry1Ac Is Independent of Alteration of the Cadherin-Like Receptor for Cry Toxins

Alteration of binding sites for Bacillus thuringiensis (Bt) toxins in insect midgut is the major mechanism of high-level resistance to Bt toxins in insects. The midgut cadherin is known to be a major binding protein for Bt Cry1A toxins and linkage of Bt-resistance to cadherin gene mutations has been identified in lepidopterans. The resistance to Bt toxin Cry1Ac evolved in greenhouse populations of Trichoplusia ni has been identified to be associated with the down-regulation of an aminopeptidase N (APN1) gene by a trans-regulatory mechanism and the resistance gene has been mapped to the locus of an ABC transporter (ABCC2) gene. However, whether cadherin is also involved with Cry1Ac-resistance in T. ni requires to be understood. Here we report that the Cry1Ac-resistance in T. ni is independent of alteration of the cadherin. The T. ni cadherin cDNA was cloned and the cadherin sequence showed characteristic features known to cadherins from Lepidoptera. Various T. ni cadherin gene alleles were identified and genetic linkage analysis of the cadherin alleles with Cry1Ac-resistance showed no association of the cadherin gene with the Cry1Ac-resistance in T. ni. Analysis of cadherin transcripts showed no quantitative difference between the susceptible and Cry1Ac-resistant T. ni larvae. Quantitative proteomic analysis of midgut BBMV proteins by iTRAQ-2D-LC-MS/MS determined that there was no quantitative difference in cadherin content between the susceptible and the resistant larvae and the cadherin only accounted for 0.0014% (mol%) of the midgut BBMV proteins, which is 1/300 of APN1 in molar ratio. The cadherin from both the susceptible and resistant larvae showed as a 200-kDa Cry1Ac-binding protein by toxin overlay binding analysis, and nano-LC-MS/MS analysis of the 200-kDa cadherin determined that there is no quantitative difference between the susceptible and resistant larvae. Results from this study indicate that the Cry1Ac-resistance in T. ni is independent of cadherin alteration

Object-centric process models and the design of flexible processes

Mainstream business process modelling techniques promote a design paradigm wherein the activities to be performed within a case, together with their usual execution order, form the backbone of a process model, on top of which other aspects are anchored. This paradigm, while eective in standardised and production-oriented domains, shows some limitations when confronted with processes where case-by-case variations and exceptions are the norm. In this thesis we develop the idea that the eective design of exible process models calls for an alternative modelling paradigm, one in which process models are modularised along key business objects, rather than along activity decompositions. The research follows a design science method, starting from the formulation of a research problem expressed in terms of requirements, and culminating in a set of artifacts that have been devised to satisfy these requirements. The main contributions of the thesis are: (i) a meta-model for object-centric process modelling incorporating constructs for capturing exible processes; (ii) a transformation from this meta-model to an existing activity-centric process modelling language, namely YAWL, showing the relation between object-centric and activity-centric process modelling approaches; and (iii) a Coloured Petri Net that captures the semantics of the proposed meta-model. The meta-model has been evaluated using a framework consisting of a set of work ow patterns. Moreover, the meta-model has been embodied in a modelling tool that has been used to capture two industrial scenarios

A preliminary formalism for variable coupling in agile systems

It is generally the case that corporate information systems consist of heterogeneous software subsystems that interact using many various processes and protocols. Applications that execute within such subsystems tend to be designed in isolation with little or no thought given to the requirements for future interaction. To provide bridges between these heterogeneous subsystems, one-off "hacked" solutions are usually introduced which rely upon maintenance of the status quo for all aspects of the execution environment and are thus inherently "brittle". Such a situation is inappropriate for large-scale and highly decentralised system deployments. In order to make such systems more robust and exhibit scalable performance characteristics, it is preferable to construct them with the ability to react to changes in the environment that they operate within. This research seeks to provide a method of how to engender "agility" into system components to improve their ability to deal with unpredictable environments. Our approach is to view systems and components from an interactive perspective and provide a middleware mechanism that enables a "variable" degree of coupling between system components. To achieve this we introduce three high-level "dimensions" of coupling, namely mediation, adaptation and crystallisation. Each dimension is characterised by the location of behaviour required for interaction and patterns of behaviour movement. The coordination characteristics of these dimensions of coupling are specified to establish a separation of coordination and application functionalities in endogenous distributed systems. The outcomes of this research project are: a definition for the dimensions of coupling that have been identified, a protocol to perform transitions between dimensions and a preliminary framework for the development of more agile applications

In brief: sharing the fruits of trade

One of CEP's core research themes is the impact of trade openness on countries, firms, regions, communities and sectors.Two recent studies confirm the gains from opening up trade - but recognise that addressing the uneven outcomes of globalisation is as big a challenge as pursuing liberalisation in the face of entrenched interests

Urbanisation and structural transformation

This paper presents new evidence on urbanization using sub-county data for the United States from 1880-2000 and municipality data for Brazil from 1970-2000. We show that the two central stylized features of population growth for cities – Gibrat’s Law and a stable population distribution - are strongly rejected when both rural and urban areas are considered. Population growth exhibits a U-shaped relationship with initial population density, and only becomes uncorrelated with initial population density at the high densities found in predominantly urban areas. We provide evidence that the explanation for these patterns lies in different employment growth dynamics in the agricultural and non-agricultural sectors and the process of structural transformation away from the agricultural sector

Object-centric process models and the design of flexible processes

Mainstream business process modelling techniques promote a design paradigm wherein the activities to be performed within a case, together with their usual execution order, form the backbone of a process model, on top of which other aspects are anchored. This paradigm, while eective in standardised and production-oriented domains, shows some limitations when confronted with processes where case-by-case variations and exceptions are the norm. In this thesis we develop the idea that the eective design of \ud exible process models calls for an alternative modelling paradigm, one in which process models are modularised along key business objects, rather than along activity decompositions. The research follows a design science method, starting from the formulation of a research problem expressed in terms of requirements, and culminating in a set of artifacts that have been devised to satisfy these requirements. The main contributions of the thesis are: (i) a meta-model for object-centric process modelling incorporating constructs for capturing \ud exible processes; (ii) a transformation from this meta-model to an existing activity-centric process modelling language, namely YAWL, showing the relation between object-centric and activity-centric process modelling approaches; and (iii) a Coloured Petri Net that captures the semantics of the proposed meta-model. The meta-model has been evaluated using a framework consisting of a set of work\ud ow patterns. Moreover, the meta-model has been embodied in a modelling tool that has been used to capture two industrial scenarios