Massively parallel implicit equal-weights particle filter for ocean drift trajectory forecasting

Forecasting of ocean drift trajectories are important for many applications, including search and rescue operations, oil spill cleanup and iceberg risk mitigation. In an operational setting, forecasts of drift trajectories are produced based on computationally demanding forecasts of three-dimensional ocean currents. Herein, we investigate a complementary approach for shorter time scales by using the recently proposed two-stage implicit equal-weights particle filter applied to a simplified ocean model. To achieve this, we present a new algorithmic design for a data-assimilation system in which all components – including the model, model errors, and particle filter – take advantage of massively parallel compute architectures, such as graphical processing units. Faster computations can enable in-situ and ad-hoc model runs for emergency management, and larger ensembles for better uncertainty quantification. Using a challenging test case with near-realistic chaotic instabilities, we run data-assimilation experiments based on synthetic observations from drifting and moored buoys, and analyze the trajectory forecasts for the drifters. Our results show that even sparse drifter observations are sufficient to significantly improve short-term drift forecasts up to twelve hours. With equidistant moored buoys observing only 0.1% of the state space, the ensemble gives an accurate description of the true state after data assimilation followed by a high-quality probabilistic forecast

Vervolgonderzoek slijmstelen bij Zantedeschia

Een van de grootste problemen bij de export van de snijbloem Zantedeschia is, dat de stelen soms gaan verslijmen. Dit wordt veroorzaakt door bacteriën. Dit verkort niet alleen het vaasleven van de Zantedeschia stelen, maar tast ook de sierwaarde van de hele bos met andere soorten bloemen aan. Het optreden van slijmstelen kan de groei van het product Zantedeschia op deze manier belemmeren. In 2007 en 2008 is onderzoek uitgevoerd binnen het project “slijmstelen bij Zantedeschia” (PT12804). Hieruit bleek, dat het onduidelijk is waar de slijmstelen veroorzakende bacteriën (Pseudomonas, Pectobacterium carotovorum subsp. carotovorum (Pcc, voorheen Erwinia)) de plant binnenkomen. Deze informatie is van belang om zo effectief mogelijk preventieve maatregelen tegen deze bacteriën te kunnen treffen. Tevens bleek aan het einde van dit onderzoek, dat een praktische toets op slijmstelen veroorzakende bacteriën wenselijk is voor de bloemenveiling FloraHolland

Agricultural Market Performance in the EU after the 2000 and 2003 CAP Reform An Ex-post Evaluation based on AGMEMOD

The paper investigates the CAP impacts on the EU agriculture by means of policy simulations conducted with the AGMEMOD model. To isolate the policy effects in the historical period 2000-2005, counterfactual simulations for this period are run. To simulate the response of the EU agriculture on different policy changes in the period 2006-2020, a ‘no-policy change’ baseline scenario is developed and then policy experiments are conducted such as the abolition of milk quota, the implementation of the regional payments and some budget cuts. To identify the policy effects, the policy scenarios are compared with the ‘no-policy change’ baseline.CAP Reform, ex-post evaluation, agricultural sector modelling, Agricultural and Food Policy,

Voorspellen van slijmstelen Zantedeschia moeilijk, voorkomen is beter

Op de bloemenveilingen is Zantedeschia een belangrijk product geworden. Minpunt van deze snijbloem is dat er slijmstelen kunnen optreden. Het onderste stengeldeel rot weg door bacteriën, zoals Erwinia en Pseudomonas die de celwand kunnen afbreken. Slijmstelen tasten de sierwaarde van mengboeketten sterk aan. Tijd voor een grondig onderzoek om de problemen te voorkomen

Erwinia: rot voor de bollenteler

De afgelopen acht jaar ondervonden bloembolgewassen zoals hyacint, Muscari, dahlia en iris in toenemende mate problemen met zachtrot : agressief snot zoals de gedupeerde telers deze bacterieziekte noemden. Agressief rot heeft geleid tot grote teeltkundige problemen en economische schade. De bacterieaantasting wordt veroorzaakt door Erwinia chrysanthemi, Erwinia carotovora subspecies carotovora, de veroorzaker van het zogenaamde "oude witsnot" tast ook bolgewassen aan, maar geeft meestal veel minder problemen. Vanaf 2004 tot eind 2007 is onderzoek aan Erwinia verricht binnen het PT-project 'Beheersing van Erwinia in bloembollen', besmettingsroutes, invloed van gewasrotatie en de productieketen op incidentie, overleving en beheersing van met name Erwinia chrysanthem

Mapping Internationalism: Congresses and Organisations in the Nineteenth and Twentieth Centuries

The Union of International Associations’ documentation on international non- governmental organizations (INGOs) is a treasure trove for historians and social scientists alike. INGOs are part and parcel of the modern world. They both reflect and influence social, political, cultural and economic conditions around the globe. They occupy a space of human activity in between, but connected to, the market and the state, and this space seems to be growing. The present chapter seeks to show how a historical investigation into this space might benefit from the use of UIA data. As other contributions to this volume have noted, the UIA aims to register the key activities of all INGOs that exist or have ever existed. As anyone familiar with historical databases would immediately admit, a database with such a large geographical (the globe) and temporal span (in principle that of human history, though in practice mostly the past two centuries) cannot, and never will be, complete in its coverage. This is also acknowledged by the UIA and is partly caused by the fact that most of the data is provided by the organizations themselves. For the present purpose – namely the visualization of various long-term developments – we will, however, assume that it can nonetheless offer a representative picture. For practical reasons, we focus on the period between 1800 and 1970, concentrating on two UIA datasets: the annual congress calendar and the Yearbook series, featuring all organizations that meet the UIA’s definition of an INGO

Gezamenlijke toetsontwikkeling op Erwinia chrysanthemi in volle gang

Erwinia bezorgde menig ondernemer de afgelopen jaren de nodige hoofdbrekens. Onderzoek door PPO reikte al een aantal oplossingen aan. Nader onderzoek is gedaan naar de mogelijkheid om partijen te toetsen. In dit artkel de achtergronden bij dit onderzoe

Complexity Framework for Forbidden Subgraphs III: When Problems Are Tractable on Subcubic Graphs

For any finite set H = {H1,. .. , Hp} of graphs, a graph is H-subgraph-free if it does not contain any of H1,. .. , Hp as a subgraph. In recent work, meta-classifications have been studied: these show that if graph problems satisfy certain prescribed conditions, their complexity can be classified on classes of H-subgraph-free graphs. We continue this work and focus on problems that have polynomial-time solutions on classes that have bounded treewidth or maximum degree at most 3 and examine their complexity on H-subgraph-free graph classes where H is a connected graph. With this approach, we obtain comprehensive classifications for (Independent) Feedback Vertex Set, Connected Vertex Cover, Colouring and Matching Cut. This resolves a number of open problems. We highlight that, to establish that Independent Feedback Vertex Set belongs to this collection of problems, we first show that it can be solved in polynomial time on graphs of maximum degree 3. We demonstrate that, with the exception of the complete graph on four vertices, each graph in this class has a minimum size feedback vertex set that is also an independent set

Bedrijfspraktijktoets op Erwinia in hyacint : geef de bol stress!!

Om een goed beeld te krijgen van de plaatsen waar risico's zitten in de verwerking van hyacinten is de afgelopen jaren onderzoek door PPO gedaan. Vooral sorteren en vallen blijken belangrijke stimulansen voor de ontwikkeling van een Erwinia-aantasting. Verder werd duidelijk dat partijen soms al latent flink met Erwinia besmet kunnen zij