Brunel, Thomas \ Verkempynck, Ruben \ Broekhoven, Wouter van \ Batsleer, Jurgen \ 2019
Abstract: This study aims at describing the spatial distribution – and its temporal variations - of discarding intensity (i.e. expected weight of discards for a standard trawl haul) for the 6 main species discarded by the Dutch beam trawl fisheries. For each species, the spatial distribution (quarterly maps for the period 2013 to 2017) is estimated using statistical models that take spatial and temporal correlation into account, which also allowed to test for the effect of a number of factors related to geography, environment, fishing practices and operational aspects on discarding. The data used to fit those models came from the observer trips and self-sampling program conducted at Wageningen Marine Research and from discards sampling trips conducted by the fishing industry. As by-product, the models provide descriptors of the temporal and spatial scales at which the discards of a given species are structured. The distribution of the expected discards per haul for dab was highly variable from quarter to quarter, with generally high discarding intensity in front of the southern coast of the Netherlands in quarter 1, a discarding intensity which is high on the German bight and low in front of the Dutch coast in quarter 3, and variable distributions for quarter 2 and 4. For plaice, the distribution was more stable, with high values consistently observed in the south of the area (between the south of the Netherlands and England), with occasional hot spots on the German bight. For sole, discards were not observed on the north-western part of the area, and a hotspot of sole discarding was found consistently in front of the southern coast of the Netherlands, occasionally expanding towards England or to the northern coast of the Netherlands. Discarding of turbot first occurred with a low intensity along the coast from Belgium to Germany. After the fourth quarter of 2015, high discarding started to occur, first limited to the small area in the southern North Sea, but progressively expanding to a larger area in the southern and central part of the North Sea, while discarding intensity remained low in the northern part of the area and in front of England. The distribution discarding intensity for whiting was highly variably, characterised by hotspots suddenly appearing for most years in the fourth quarter, and disappear in the following first quarter. Discarding of rays occurred mainly in the western part of the area, especially in front of southern England, with an increasing level since the fourth quarter of 2016. The distributions observed and their variability were further discussed in the light the available information on the distribution and migration of the species and on the management measures potentially influencing discarding.
Abstract: Lowland streams are being restored to their natural situation throughout Europe. However, a lot of projects do not meet their goals. Furthermore, there is a knowledge gap on the restoration demands and the current understanding on the morphodynamics of low-energy streams. The focus of this thesis is on the morphodynamic evolution of the lowland stream the Dommel, in The Netherlands. The Dommel is located in the Roer Valley Graben and flows in the sandy deposits of the Boxtel formation. Due to the subsidence of the Roer Valley Graben, it is a good location to study sediment deposits. The used methods, are a combination of literature, Ground Penetrating Radar (GPR), auguring and Optical Stimulated Luminescence (OSL) dating. The results indicate a succession that started with a braided system during the Pleniglacial, to a large meandering system in the Late Glacial. Towards the end of the Younger Dryas the large meanders were abandoned and the system shifted to a lower energetic meandering system and eventually an immobile system. The stream kept its immobile river pattern until anthropogenic land use affected the stream by increasing the stream power, causing the Dommel to transit to a more energetic meandering pattern during the Bronze Age (Late Subboreal). It is concluded that the Dommel would have remain lateral immobile, if there were no anthropogenic influences in the catchment.
Wallace, Rodrick \ Chaves, Luis Fernando \ Bergmann, Luke R.. \ Ayres, Constńcia \ Hogerwerf, Lenny \ Kock, Richard \ Wallace, Robert G.. \ 2018
Abstract: The vector-borne Zika virus joins avian influenza, Ebola, and yellow fever as recent public health crises threatening pandemicity. By a combination of stochastic modeling and economic geography, this book proposes two key causes together explain the explosive spread of the worst of the vector-borne outbreaks. Ecosystems in which such pathogens are largely controlled by environmental stochasticity are being drastically streamlined by both agribusiness-led deforestation and deficits in public health and environmental sanitation. Consequently, a subset of infections that once burned out relatively quickly in local forests are now propagating across susceptible human populations whose vulnerability to infection is often exacerbated in structurally adjusted cities. The resulting outbreaks are characterized by greater global extent, duration, and momentum. As infectious diseases in an age of nation states and global health programs cannot, as much of the present modeling literature presumes, be described by interacting populations of host, vector, and pathogen alone, a series of control theory models is also introduced here. These models, useful to researchers and health officials alike, explicitly address interactions between government ministries and the pathogens they aim to control.
Abstract: The main object of this book is to explain some of the mechanisms of integration and secession among regions from the point of view of game theory. To attain this goal, the incentives of regions in a country to unite or to secede and the conditions in the way for the member countries of a federation to leave peacefully are examined. Tensions over secession have become more and more serious, including separatist tensions in China, India, Iraq, Myanmar, and Sri Lanka. Studies included in this book stress differing preferences in the type of policy in each region and the influence of a third region on the power of secession. Decentralization strategies of tax-subsidy policy and governance policy in a political or economic group composed of two regions are shown to be important as a way to avoid wasteful conflict for the secession incentive of a minority region. How those incentives depend on heterogeneity costs associated with different preferences over the type of region and the relative size of the two regions is shown. Also provided is an analytical framework in which secessions are the equilibrium outcome of explicit civil conflict, where regions with different preferences invest in costly conflict activities. Finally, an empirical analysis is made of determinant factors of secession movements in many regions to verify the validity of our theories of secession. This book is recommended to researchers who are interested in a new economic geography and an interdisciplinary approach for regional economics.
To support researchers to publish their research Open Access, deals have been negotiated with various publishers. Depending on the deal, a discount is provided for the author on the Article Processing Charges that need to be paid by the author to publish an article Open Access. A discount of 100% means that (after approval) the author does not have to pay Article Processing Charges.
For the approval of an Open Access deal for an article, the corresponding author of this article must be affiliated with Wageningen University & Research.
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.