Tradeoffs in Trade Data: Do Our Assumptions Affect Our Results?

Researchers investigating the link between trade and peace often face a severe problem of list-wise deletion from missing trade data. Attempts to mitigate this problem include assuming that most observations are zero or imputing the values of such flows. We compare two frequently used trade data sets (the Gleditsch data set and the Correlates of War Project data set). We classify individual observations as observed, constructed or missing. We demonstrate that state attributes are systematically related to different categories of trade data. Using Monte Carlo simulations, we also find that replacing some missing data with estimated values tends to inflate the effects of trade in conflict models, although the effects differ by data set

Assemblage urbanism: the role of heritage in urban placemaking

Purpose: The paper explores the potential value of urban assemblage theory as a conceptual framework for understanding the role heritage has in social sustainable urban placemaking. The authors conceptualise urban placemaking as a dynamic and complex social assemblage. Heritage is one of the many dimensions of such a complex and dynamic urban assembly. Based on the approach to urban assemblage theory, the authors aim to uncover how postindustrial city-making unfolds. When approaching the case studies, the authors ask the following: Whose city for which citizens are visible through the selected case studies? How is social sustainability achieved through heritage in urban placemaking? Design/methodology/approach: The main research material is derived from theoretical literature and the testing of an assemblage methodological approach through three Norwegian urban regeneration case studies where heritage partake in urban placemaking. The three case studies are the Tukthus wall (what is left of an 19th century old prison), the Vulkan neighbourhood (an 19th century industrial working area) and Sørengkaia (an 19th century industrial harbour area) in Oslo, Norway. The three case studies are representing urban regeneration projects which are common worldwide, and not at least in a European context. Findings: The paper reveals the dynamic factors and processes at play in urban placemaking, which has its own distinct character by the uses of heritage in each of the case study areas. Placemaking could produce “closed” systems which are stable in accordance with its original functions, or they could be “open” systems affected by the various drivers of change. The paper shows how these forces are depending on two sets of binary forces at play in urban placemaking: forces of “assemblages” co-creating a place versus destabilising forces of “disassembly” which is redefining the place as a process affected by reassembled placemaking. Research limitations/implications: For research, the authors focus on the implications this paper has for the field of urban heritage studies as it provides a useful framework to capture the dynamic complexity of urban heritage areas. Practical implications: For practice, the authors state that the paper can provide a useful platform for dialogue and critical thinking on strategies being planned. Social implications: For society, the paper promotes the significance in terms of fostering an inclusive way of thinking and planning for urban heritage futures. Originality/value: The paper outlines dynamics of urban regeneration through heritage which are significant for understanding urban transformation as value for offering practical solutions to social problems in urban planning. The assemblage methodological approach (1) makes awareness of the dynamic processes at play in urban placemaking and makes the ground for mapping issue at stake in urban placemaking; (2) becomes a source for modelling urban regeneration through heritage by defining a conceptual framework of dynamic interactions in urban placemaking; and (3) defines a critically reflexive tool for evaluating good versus bad (heritage-led) urban development projects

The shape of things to come? Expanding the inequality and grievance model for civil war forecasts with event data

© The Author(s) 2017. We examine if dynamic information from event data can help improve on a model attempting to forecast civil war using measures reflecting plausible motivation and grievances. Buhaug, Cederman, and Gleditsch predict the risk of civil war using a horizontal inequality model with measures reflecting motivation and relevant group characteristics at the country level. The predictions from their model outperform in an out-of-sample forecast conventional countrylevel models of civil war, emphasizing vertical inequality and country characteristics. However, most grievance measures change little over time. We surmise that a model reflecting potential motivation for conflict can be improved with more dynamic information on mobilization and the behavior of actors. Our conjecture receives some support in the empirical analysis, where we consider both conflict onset and termination over territorial and governmental incompatibilities in the Uppsala/PRIO Armed Conflict Data, and find some evidence that event data can help improve forecasts. Moreover, models with the original grievance measures do better than purely event based models, supporting our claim that both structure and event based components can add value to conflict prediction models. However, the contribution of events to improving predictive power is modest and not entirely consistent, and some types of conflict events seem easier to forecast than others

Network Structure of Insurgent Groups and the Success of DDR Processes in Colombia

We argue that organizational structure of insurgent organizations influences the prospects for success in a disarmament, demobilization, and reintegration process (DDR). In concrete, we argue that more cohesive, tighter, networks have higher levels of supervision and control on its military units and increase the probability of successful DDR processes. In order to evaluate our hypotheses, we use the theory of networks to map and characterize the network structure of the United Self-Defense Forces of Colombia (AUC) and the Revolutionary Armed Forces of Colombia (FARC). Our results suggest that armed military units grouped in smaller and more isolated components on the network remilitarize with higher probability with respect to other units on the network. Also, we find that military units with high degree of centrality on the network play an important role for the risk of conflict recurrence and success in a DDR process

The developmental dynamics of terrorist organizations

We identify robust statistical patterns in the frequency and severity of violent attacks by terrorist organizations as they grow and age. Using group-level static and dynamic analyses of terrorist events worldwide from 1968-2008 and a simulation model of organizational dynamics, we show that the production of violent events tends to accelerate with increasing size and experience. This coupling of frequency, experience and size arises from a fundamental positive feedback loop in which attacks lead to growth which leads to increased production of new attacks. In contrast, event severity is independent of both size and experience. Thus larger, more experienced organizations are more deadly because they attack more frequently, not because their attacks are more deadly, and large events are equally likely to come from large and small organizations. These results hold across political ideologies and time, suggesting that the frequency and severity of terrorism may be constrained by fundamental processes.Comment: 28 pages, 8 figures, 4 tables, supplementary materia

Neutrophil-derived reactive agents induce a transient SpeB negative phenotype in Streptococcus pyogenes

Background Streptococcus pyogenes (group A streptococci; GAS) is the main causative pathogen of monomicrobial necrotizing soft tissue infections (NSTIs). To resist immuno-clearance, GAS adapt their genetic information and/or phenotype to the surrounding environment. Hyper-virulent streptococcal pyrogenic exotoxin B (SpeB) negative variants caused by covRS mutations are enriched during infection. A key driving force for this process is the bacterial Sda1 DNase. Methods Bacterial infiltration, immune cell influx, tissue necrosis and inflammation in patient´s biopsies were determined using immunohistochemistry. SpeB secretion and activity by GAS post infections or challenges with reactive agents were determined via Western blot or casein agar and proteolytic activity assays, respectively. Proteome of GAS single colonies and neutrophil secretome were profiled, using mass spectrometry. Results Here, we identify another strategy resulting in SpeB-negative variants, namely reversible abrogation of SpeB secretion triggered by neutrophil effector molecules. Analysis of NSTI patient tissue biopsies revealed that tissue inflammation, neutrophil influx, and degranulation positively correlate with increasing frequency of SpeB-negative GAS clones. Using single colony proteomics, we show that GAS isolated directly from tissue express but do not secrete SpeB. Once the tissue pressure is lifted, GAS regain SpeB secreting function. Neutrophils were identified as the main immune cells responsible for the observed phenotype. Subsequent analyses identified hydrogen peroxide and hypochlorous acid as reactive agents driving this phenotypic GAS adaptation to the tissue environment. SpeB-negative GAS show improved survival within neutrophils and induce increased degranulation. Conclusions Our findings provide new information about GAS fitness and heterogeneity in the soft tissue milieu and provide new potential targets for therapeutic intervention in NSTIs.publishedVersio

Mutagenesis and expression of methane monooxygenase to alter regioselectivity with aromatic substrates

Soluble methane monooxygenase (sMMO) from methane-oxidising bacteria can oxygenate more than 100 hydrocarbons and is one of the most catalytically versatile biological oxidation catalysts. Expression of recombinant sMMO has to date not been achieved in Escherichia coli and so an alternative expression system must be used to manipulate it genetically. Here we report substantial improvements to the previously described system for mutagenesis of sMMO and expression of recombinant enzymes in a methanotroph (Methylosinus trichosporium OB3b) expression system. This system has been utilised to make a number of new mutants and to engineer sMMO to increase its catalytic precision with a specific substrate whilst increasing activity by up to 6-fold. These results are the first 'proof-of-principle' experiments illustrating the feasibility of developing sMMO-derived catalysts for diverse applications. [Abstract copyright: © FEMS 2017.

The Diffusion of Inclusion: An Open Polity Model of Ethnic Power Sharing

While there is a growing consensus that ethnic inclusion produces peace, less is known about what causes transitions to power sharing between ethnic groups in central governments in multiethnic states. The few studies that have addressed this question have proposed explanations stressing exclusively domestic factors. Yet, power sharing is spatially clustered, which suggests that diffusion may be at play. Inspired by studies of democratic diffusion, we study the spread of inclusive policies with an “open polity model” that explicitly traces diffusion from inclusion in other states. Our findings indicate that the relevant diffusion processes operate primarily at the level of world regions rather than globally or between territorial neighbors. Thus, the more inclusive the region, the more likely a shift to power sharing becomes. Shifts away from inclusion to dominance are less common since World War II, but they are more likely in regional settings characterized by ethnic exclusion