Generalized gaugings and the field-antifield formalism

We discuss the algebra of general gauge theories that are described by the embedding tensor formalism. We compare the gauge transformations dependent and independent of an invariant action, and argue that the generic transformations lead to an infinitely reducible algebra. We connect the embedding tensor formalism to the field-antifield (or Batalin-Vilkovisky) formalism, which is the most general formulation known for general gauge theories and their quantization. The structure equations of the embedding tensor formalism are included in the master equation of the field-antifield formalism.Comment: 42 pages; v2: some clarifications and 1 reference added; version to be published in JHE

Achtergrondstudie bij de subsidies voor de biologische land- en tuinbouw in Vlaanderen

In opdracht van de Vlaamse overheid heeft het Louis Bolk Instituut, samen met het Instituut voor landbouw- en visserijonderzoek (ILVO), een studie uitgevoerd naar de bedrijfseconomische gevolgen van de omschakeling van gangbare naar biologische landbouw. Aanleiding voor de studie waren een mogelijke herziening van de hoogte van de overheidssubsidie die biologische landbouwers in Vlaanderen hiervoor ontvangen en het geringe aantal omschakelende agrariërs. Conclusie van de studie is dat voor veel bedrijven omschakeling naar biologische landbouw een rendabel alternatief kan vormen. De studie bevestigt tevens een aantal fundamentele kwetsbaarheden en obstakels. Transitiekosten (het vergaren van nieuwe kennis en marktcontacten, de afzet van de producten en voor sommige bedrijven desinvesteringen tijdens de overgangsperiode) kunnen een groot obstakel vormen voor omschakeling omdat deze transitiekosten pas na vele jaren worden terugverdiend. Daarnaast kan het risico op marktfalen goed bedrijfsresultaat in de weg staan. Deze kwetsbaarheden en obstakels manifesteren zich vooral op bedrijfsniveau waardoor ze moeilijker toewijsbaar worden naar teeltniveau. Een van de aanbevelingen is daarom om (ook) instrumenten te ontwikkelen die de overgangskosten en het risico op marktfalen verminderen. Doordat omschakeling voor veel bedrijven een aantrekkelijke optie lijkt en belangrijke kostencomponenten zich vooral op bedrijfsniveau manifesteren is een blijvende en op hectarebasis teruggebrachte ondersteuningspremie voor biologische landbouw nog slechts beperkt te verantwoorden. Aangezien prijzen continue wisselen en de beschikbaarheid van betrouwbare gegevens beperkt is, is ook een ‘beslissingsondersteunend rekenmodel’ opgeleverd waarmee berekeningen gemakkelijk later opnieuw gedaan kunnen worden

Upscaling a district heating system based on biogas cogeneration and heat pumps

The energy supply of the Meppel district Nieuwveense landen is based on biogas cogeneration, district heating, and ground source heat pumps. A centrally located combined heat and power engine (CHP) converts biogas from the municipal wastewater treatment facility into electricity for heat pumps and heat for district heating purposes. Development of the urban district is influenced by the current economic and building decline. For the district heating energy concept, a migration strategy for the required infrastructure is required. The migration spans the district’s small-scale starting phase involving 40 houses up to a scale of 176 houses. An optimization model which maximizes profitability is developed which includes data from district heating and cooling demand patterns. With the optimization model, optimal CHP size, boiler size, and operational hours are determined for various scenarios. From the scenario analysis, a migration strategy is developed which starts with a simple system concept supported by boilers to a larger system which includes a CHP. Sustainability in terms of CO2 emission savings of the energy concept is compared with other possible energy concepts

Electric/magnetic duality for chiral gauge theories with anomaly cancellation

We show that 4D gauge theories with Green-Schwarz anomaly cancellation and possible generalized Chern-Simons terms admit a formulation that is manifestly covariant with respect to electric/magnetic duality transformations. This generalizes previous work on the symplectically covariant formulation of anomaly-free gauge theories as they typically occur in extended supergravity, and now also includes general theories with (pseudo-)anomalous gauge interactions as they may occur in global or local N=1 supersymmetry. This generalization is achieved by relaxing the linear constraint on the embedding tensor so as to allow for a symmetric 3-tensor related to electric and/or magnetic quantum anomalies in these theories. Apart from electric and magnetic gauge fields, the resulting Lagrangians also feature two-form fields and can accommodate various unusual duality frames as they often appear, e.g., in string compactifications with background fluxes.Comment: 37 pages; v2: typos corrected and 1 reference adde

Effective Actions near Singularities

We study the heterotic string compactified on K3 x T^2 near the line T=U, where the effective action becomes singular due to an SU(2) gauge symmetry enhancement. By `integrating in' the light W^\pm vector multiplets we derive a quantum corrected effective action which is manifestly SU(2) invariant and non-singular. This effective action is found to be consistent with a residual SL(2,Z) quantum symmetry on the line T=U. In an appropriate decompactification limit, we recover the known SU(2) invariant action in five dimensions.Comment: 33 pages, LaTeX. v2: cosmetic correction on titlepage. v3: references and note adde

Training telescope operators and support astronomers at Paranal

The operations model of the Paranal Observatory relies on the work of efficient staff to carry out all the daytime and nighttime tasks. This is highly dependent on adequate training. The Paranal Science Operations department (PSO) has a training group that devises a well-defined and continuously evolving training plan for new staff, in addition to broadening and reinforcing courses for the whole department. This paper presents the training activities for and by PSO, including recent astronomical and quality control training for operators, as well as adaptive optics and interferometry training of all staff. We also present some future plans.Comment: Paper 9910-123 presented at SPIE 201

Entropy Maximization in the Presence of Higher-Curvature Interactions

Within the context of the entropic principle, we consider the entropy of supersymmetric black holes in N=2 supergravity theories in four dimensions with higher-curvature interactions, and we discuss its maximization at points in moduli space at which an excess of hypermultiplets becomes massless. We find that the gravitational coupling function F^(1) enhances the maximization at these points in moduli space. In principle, this enhancement may be modified by the contribution from higher F^(g)-couplings. We show that this is indeed the case for the resolved conifold by resorting to the non-perturbative expression for the topological free energy.Comment: 22 pages, 8 figures, AMS-LaTe

Symplectic structure of N=1 supergravity with anomalies and Chern-Simons terms

The general actions of matter-coupled N=1 supergravity have Peccei-Quinn terms that may violate gauge and supersymmetry invariance. In addition, N=1 supergravity with vector multiplets may also contain generalized Chern-Simons terms. These have often been neglected in the literature despite their importance for gauge and supersymmetry invariance. We clarify the interplay of Peccei-Quinn terms, generalized Chern-Simons terms and quantum anomalies in the context of N=1 supergravity and exhibit conditions that have to be satisfied for their mutual consistency. This extension of the previously known N=1 matter-coupled supergravity actions follows naturally from the embedding of the gauge group into the group of symplectic duality transformations. Our results regarding this extension provide the supersymmetric framework for studies of string compactifications with axionic shift symmetries, generalized Chern-Simons terms and quantum anomalies.Comment: 27 pages; v2: typos corrected; version to be published in Class.Quantum Gra

Energy scheduling model to optimize transition routes towards 100% renewable urban districts

The purpose of this paper is to develop a model to analyze options for 100% renewable urban districts which self-consume locally generated renewable energy as much as possible and import (or export) energy from (or to) external grids as little as possible. Energy scheduling algorithms are developed to prioritize energy generation and storage of local renewable energy. The model is applied in a Dutch case study in which three renewable energy system concepts are evaluated against the case reference. Optimal capacities are determined for minimal operational costs including a penalty on carbon dioxide production. Attractiveness of these concepts is discussed in relation to costs, environmental concerns and applicability within the Dutch context of the energy transition

Extremal non-BPS black holes and entropy extremization

At the horizon, a static extremal black hole solution in N=2 supergravity in four dimensions is determined by a set of so-called attractor equations which, in the absence of higher-curvature interactions, can be derived as extremization conditions for the black hole potential or, equivalently, for the entropy function. We contrast both methods by explicitly solving the attractor equations for a one-modulus prepotential associated with the conifold. We find that near the conifold point, the non-supersymmetric solution has a substantially different behavior than the supersymmetric solution. We analyze the stability of the solutions and the extrema of the resulting entropy as a function of the modulus. For the non-BPS solution the region of attractivity and the maximum of the entropy do not coincide with the conifold point.Comment: 19 pages, 4 figures, AMS-LaTeX, reference adde