Economic Geography and the Evolution of Networks

An evolutionary perspective on economic geography requires a dynamic understanding of change in networks. This paper explores theories of network evolution for their use in geography and develops the conceptual framework of geographical network trajectories. It specifically assesses how tie selection constitutes the evolutionary process of retention and variation in network structure and how geography affects these mechanisms. Finally, a typology of regional network formations is used to discuss opportunities for innovation in and across regions.evolution, network trajectory, evolutionary economic geography, social network analysis, innovation

Crowdsourcing the Robin Hood effect in cities

Socioeconomic inequalities in cities are embedded in space and result in neighborhood effects, whose harmful consequences have proved very hard to counterbalance efficiently by planning policies alone. Considering redistribution of money flows as a first step toward improved spatial equity, we study a bottom-up approach that would rely on a slight evolution of shopping mobility practices. Building on a database of anonymized credit card transactions in Madrid and Barcelona, we quantify the mobility effort required to reach a reference situation where commercial income is evenly shared among neighborhoods. The redirections of shopping trips preserve key properties of human mobility, including travel distances. Surprisingly, for both cities only a small fraction ($\sim 5 \%$) of trips need to be altered to reach equity situations, improving even other sustainability indicators. The method could be implemented in mobile applications that would assist individuals in reshaping their shopping practices, to promote the spatial redistribution of opportunities in the city.Comment: 9 pages, 4 figures + Appendi

Conceptualizing the Role of Geographical Proximity in Project Based R&D Networks: A Literature Survey

Empirical evidence shows that research is being carried out more in cooperation or in collaboration with others, and the networks described by these collaborative research activities are becoming more and more complex. This phenomenon brings about new strands of research questions and opens up a different research context in the area of geography of innovation. The recent set of literature addressing these new issues shows a high degree of variation in terms of focus, approaches and methodology. Hence to elucidate the relationship between networks and geography it is crucial to have a review them. In this regard, this study focuses on a particular type of networks, namely, project based R&D networks and aims at describing the state-of-the-art in explaining the specificity of geography in formation and evolution of such networks. Towards this aim, we framed the discussion along four lenses: the specificity of geography in partner choice, in successful execution of the collaboration, in the resulting innovation performance both at the organizational and regional level, and the spatio-temporal evolution of networks. The overview provided by the survey is suggestive regarding the theorization of geography and network relationship, and informative regarding the issues demanding further research effort, and promising extensions.

Governing network evolution in the quest for identity

This paper provides a managerial account of network governance by exploring how initially non-powerful agents, driven by the quest for distinctive identity, shape the governance of their networks over time. The research design is that of a longitudinal comparative case study of the trajectories of three renowned, Oscar-winning Spanish filmmakers. It scrutinizes data coming from original interviews, as well as from multiple secondary data sources, in order to illustrate the propositions advanced. The paper's contribution is sought: 1) in proposing a micro-level framework for systematic thinking about network governance evolution, distinguishing four dimensions (co-governance, structure, strategy, and pace) and their respective sub-categories; 2) in advancing three peculiar identity profiles with different implications for the evolution of network governance (i.e., a maverick, an integrated professional, and a broker); 3) in bringing together two bodies of literature that have not conversed frequently (i.e., network governance and identity) in a largely overlooked cultural and historical context, that of Spain after the transition to democracy in 1975.Network governance; Management

Modeling the mechanics of amorphous solids at different length and time scales

We review the recent literature on the simulation of the structure and deformation of amorphous glasses, including oxide and metallic glasses. We consider simulations at different length and time scales. At the nanometer scale, we review studies based on atomistic simulations, with a particular emphasis on the role of the potential energy landscape and of the temperature. At the micrometer scale, we present the different mesoscopic models of amorphous plasticity and show the relation between shear banding and the type of disorder and correlations (e.g. elastic) included in the models. At the macroscopic range, we review the different constitutive laws used in finite element simulations. We end the review by a critical discussion on the opportunities and challenges offered by multiscale modeling and transfer of information between scales to study amorphous plasticity.Comment: 58 pages, 14 figure

Network brokerage:An integrative review and future research agenda

Network brokerage research has grown rapidly in recent decades, spanning the boundaries of multiple social science disciplines as well as diverse research areas within management. Accordingly, we take stock of the literature on network brokerage and provide guidance on ways to move this burgeoning research area forward. We provide a comprehensive review of this literature, including crucial dimensions of the concept itself in terms of brokerage structure and behavior, a set of key categories of factors surrounding the brokerage concept (antecedents, outcomes, and moderators), and an overview of brokerage dynamics over time. We use these dimensions and categories to depict network brokerage’s theoretical and empirical underpinnings as well as evaluate prior research efforts. In so doing, we offer a means to summarize and synthesize this large, interdisciplinary literature, identify important research gaps, and offer promising directions for future research

Reproducible Prediction of Organic Semiconductor Properties Through Open Source Software Development

Semiconducting materials made from carbon-based molecules are potential replacements for inorganic semiconductors, but with lower costs of processing. Devices made from organic semiconductors can be produced at scale by inkjet printing and roll-to-roll manufacturing of these molecules in solution or melt phases. The efficiency of these organic devices is dependent on the structure of the active layer, so controlling the morphology of organic molecules through self-assembly during manufacturing is a key challenge to realizing their utility. Molecular self-assembly depends on the chemical structure of the molecules, how key moieties interact with each other and with any solvent present, and the thermodynamic paths that are sampled during processing. Computer simulations of molecular self-assembly can predict the structure and properties of candidate systems, and can improve the amount of information gained from more expensive trials performed in a wet lab when used to guide and explain experiments. Here we focus on the prediction of charge mobility in organic semiconducting materials, which requires a sequence of modeling calculations spanning many orders of magnitude across both time and space. We describe an open-source `pipeline\u27 of calculations that serves as a virtual laboratory for the screening of organic semiconductors for their charge transport properties. We describe work on Planckton, a software package for managing molecular simulations of organic semiconductors, and MorphCT, a package for managing kinetic Monte Carlo simulations, the modularization and testing of which improves their transparency, usability, reproducibility, and extensibility. We measure improvements to Planckton and MorphCT by using them to study two organic molecules of interest in the photovoltaics field. In the first case study, of semiconducting polymer Poly-(3-hexylthiophene) (P3HT), we validate qualitative trends of charge mobility against prior work from both simulation and experiment. In the second case we predict the morphology and charge transport of the semiconducting macromolecule 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)- indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2\u27,3\u27-d\u27]-s-indaceno[1,2-b: 5,6-b\u27]dithiophene (ITIC). We find that our work modularizing Planckton improves the pace at which simulations can be iteratively tested. We validate the electronic structure predictions made by pySCF against those previously made by the more restrictively-licensed orca package. We measure specific features of local structure that contribute to large-scale mobility trends in P3HT and describe predictions of charge transport in ITIC. In sum we improve the software ecosystem for reproducibly predicting charge mobility in organic semiconductors

Revising the Orchestral Reduction of Jacques Ibert\u27s Concerto for Flute and Orchestra

Given the popularity of Jacques Ibert’s Concerto for Flute and Orchestra amongst flautists, and the frequent need to perform the work with a pianist, the high-difficulty threshold of its current reduction for piano may prove to be a potential liability for both soloist and collaborator. For this project, solutions to the complications that arise as a result of the Concerto’s burdensome piano reduction were investigated. This investigation ultimately led to the construction of a carefully reworked version of the original orchestra reduction for piano—i.e., a revision. The purpose of this paper is to explain the editorial choices that went into revising and reconstructing the reduction, as well as to resolve any issues a pianist might have pertaining to its performance

High magnitude and rapid incision from river capture: Rhine River, Switzerland

Landscape evolution is controlled by the development and organization of drainage basins. As a landscape evolves, drainage reorganization events can occur via river capture or piracy, whereby one river basin grows at the expense of another. The river downstream of a capture location will generate a transient topographic response as the added water discharge increases sediment transport and erosion efficiency. This erosional response will propagate upstream through both the captured and original river basins. Here we focus on quantifying the impact of drainage reorganization along the Rhine/Aare River system (~45,000 km 2 ) during the late Pliocene/early Pleistocene, where gravel remnants indicate total incision of ~650 m during the last ~4.2 Myr in the region of the recent Aare‐Rhine confluence. We develop a numerical model of drainage capture to quantify the range of possible magnitudes of erosion and the transient river response resulting from the reorganization of the Rhine River. The model accounts for both fluvial incision and sediment transport. Our model estimates 400–800 m of river elevation change (lowering profiles) during the last ~4 Myr due to river capture events, providing an important component to the recent exhumation budget of the Swiss Alpine Foreland. The model indicates a rapid response to capture events (re‐equilibration timescale of ~1 Myr). The predicted incision magnitudes are consistent with incision measured from the elevation of Pliocene and early Pleistocene river gravels, suggesting that across northern Switzerland, a significant amount of incision can be explained by drainage reorganization. Key Points Drainage capture has caused significant erosion along the Rhine River The transient erosional wave propagates quickly through the landscape The incision is a significant fraction of Plio‐Pleistocene erosion in the regionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99064/1/jgrf20056.pd