Comparing phenomenological recipes with a microscopic model for the electric amplitude in strangeness photoproduction

Corrections to the Born approximation in photo-induced strangeness production off a proton are calculated in a semi-realistic microscopic model. The vertex corrections and internal contributions to the amplitude of the $\gamma p \to K^+ \Lambda$ reaction are included on the one-loop level. Different gauge-invariant phenomenological prescriptions for the modification of the Born contribution via the introduction of form factors and contact terms are discussed. In particular, it is shown that the popular minimal-substitution method of Ohta corresponds to a special limit of the more realistic approach.Comment: 10 pages, 6 figures in the tex

Estimating submarine groundwater discharge into the Ria Formosa lagoon, Portugal: Uncertainties in the lagoon-open ocean radium exchange

The Ria Formosa lagoon is the most important resource for the fishing, aquaculture and tourism industries of southern Portugal. The lagoon expands across an area of approximately 100 km²and about half of its area is intertidal, covered with muddy sand and saltmarshes. The lagoon is shallow (2 m average depth) with semidiurnal tides at amplitudes between 1.3 m and 3 m (during neap and spring tides respectively) causing a relatively rapid renewal of water through three inlets at time scales shorter than 5 days. The hinterland is characterized by intensive agriculture leading to elevated nitrate concentrations in coastal groundwaters. To quantify the amount of submarine groundwater discharge (SGD) and possible associated nutrient fluxes to the lagoon radium concentrations (223Ra, 224Ra, 228Ra, 226Ra) were measured during low and high spring tides in December 2009 and May 2010 using standard techniques (delayed coincidence counting, gamma spectrometry). A radium mass balance model accounting for all major sources and sinks of radium was employed to derive quantitative estimates of SGD. In order to avoid biases due to non-representative sampling, areal average radium concentrations were generated using the ArcGIS spatial analyst interpolation scheme. Radium exchange with the open ocean was the most significant parameter in the mass balance calculations. Three independent models were used to calculate this exchange flux: i) a tidal prism model using radium to calculate the return flow factor, ii) a hydrographic model providing outflow and inflow water fluxes for the Ria Formosa lagoon; and by combining these fluxes with the average concentrations measured at the inlet; iii) a model which estimates the exchange with the ocean based on the radium residence time calculated from the water exposure time in the lagoon. For each of these models we calculated SGD based on 223Ra, 224Ra and 226Ra mass balances the differences being at a maximum no greater than 35 %. However, the results from the models differed up to a factor of 2 with the tidal prism model producing the highest estimate and the residence time model the lowest estimates. We will discuss possible causes for the differences in the model results

A new limit on the Ultra-High-Energy Cosmic-Ray flux with the Westerbork Synthesis Radio Telescope

A particle cascade (shower) in a dielectric, for example as initiated by an ultra-high energy cosmic ray, will have an excess of electrons which will emit coherent \v{C}erenkov radiation, known as the Askaryan effect. In this work we study the case in which such a particle shower occurs in a medium just below its surface. We show, for the first time, that the radiation transmitted through the surface is independent of the depth of the shower below the surface when observed from far away, apart from trivial absorption effects. As a direct application we use the recent results of the NuMoon project, where a limit on the neutrino flux for energies above $10^{22}$\,eV was set using the Westerbork Synthesis Radio Telescope by measuring pulsed radio emission from the Moon, to set a limit on the flux of ultra-high-energy cosmic rays.Comment: Accepted for publication in Phys. Rev.

Measures of self-regulation used in adult rehabilitation populations:A systematic review and content screening

Objective We aimed to identify generic measures of self-regulation and to examine the degree to which these measures fit a recently developed conceptual model of self-regulation in a rehabilitation context. Data sources Pubmed, Embase, PsycInfo, and CINAHL were searched. Review methods Articles were included if they were published between January 2015 and August 2020 and reported on empirical studies (trials and observational studies) using a measure of self-regulation or a related concept, in an adult rehabilitation population. Main content was analysed by linking all items of the selected measures to one or more of the six sub-themes of self-regulation: (1) insight into physical and cognitive impairments, (2) insight into the consequences of the impairments, (3) insight into abilities, (4) to be able to communicate limitations, (5) trust in body and functioning, and (6) make use of abilities. Results Two reviewers independently screened 7808 abstracts, resulting in the inclusion of 236 articles. In these articles, 80 different measures were used to assess self-regulation or related concept. Nineteen of these measures met the inclusion criteria and were included for the content analyses. Nine of these were self-efficacy measures. No measures covered four or more of the six sub-themes of self-regulation. The three sub-themes on gaining insights were covered less compared to the sub-domains 'trust' and 'make use of abilities'. Conclusions Many measures on self-regulation exist None of these measures cover all six sub-themes of self-regulation considered important to measure self-regulation as a rehabilitation outcome

Integrated Structure and Semantics for Reo Connectors and Petri Nets

In this paper, we present an integrated structural and behavioral model of Reo connectors and Petri nets, allowing a direct comparison of the two concurrency models. For this purpose, we introduce a notion of connectors which consist of a number of interconnected, user-defined primitives with fixed behavior. While the structure of connectors resembles hypergraphs, their semantics is given in terms of so-called port automata. We define both models in a categorical setting where composition operations can be elegantly defined and integrated. Specifically, we formalize structural gluings of connectors as pushouts, and joins of port automata as pullbacks. We then define a semantical functor from the connector to the port automata category which preserves this composition. We further show how to encode Reo connectors and Petri nets into this model and indicate applications to dynamic reconfigurations modeled using double pushout graph transformation

Current Results of the EC-sponsored Catchment Modelling (CatchMod) Cluster

To support the Water Framework Directive implementation, much research has been commissioned at both national and European levels. CatchMod is a cluster of these projects, which is focusing on the development of computational catchment models and related tools. This paper presents an overview of the results of the CatchMod cluster to dat

An air shower array for LOFAR: LORA

LOFAR is a new form of radio telescope which can detect radio emission from air showers induced by very high-energy cosmic rays. It can also look for radio emission from particle cascades on the Moon induced by ultra high-energy cosmic rays or neutrinos. To complement the radio detection, we are setting up a small particle detector array LORA (LOfar Radboud Air shower array) within an area of $\sim 300$ m diameter in the LOFAR core. It will help in triggering and confirming the radio detection of air showers with the LOFAR antennas. In this paper, we present a short overview about LORA and discuss its current status.Comment: 10 pages (using article.cls), 6 figures, accepted for the proceedings of 22nd European Cosmic Ray Symposium, 3-6 August 2010, Finlan