Model Based Assessment of Nitrate Pollution of Water Resources on a Federal State Level for the Dimensioning of Agro-environmental Reduction Strategies

The main goal of the project was to assess nitrogen pollution of surface waters and groundwater in the Federal State of North Rhine Westphalia (NRW), Germany. For this purpose the hydro(geo-)logical models GROWA-DENUZ/WEKU were coupled to the agro-economic model RAUMIS in order to assess the diffuse nitrogen loads and to approaches to determine the nitrogen loads from point sources. In this way the complex socio-economic interrelations and hydrological/hydrogeological interdependencies were simultaneously. The model network was applied consistently across the whole territory of NRW. At first the actual N inputs into groundwater and surface waters resulting from diffuse sources and point sources were assessed. For the relevant diffuse input pathways (groundwater runoff, drainage runoff and natural interflow) this was done in a spatial resolution of 100 m???100 m. In the case of point source inputs information from municipal waste water treatment plants, industrial effluents, rainwater sewers and combined sewer overflows has been considered. For NRW an actual total N input into surface waters of ca. 117.000 t???a^?1?N has been quantified. As the inputs via natural interflow (ca. 30 %), groundwater runoff (ca. 26 %) and drainage systems (ca. 18 %) hold the largest portion, it is evident that measures to control nitrate pollution have to focus on the inputs from diffuse sources. For this purpose, initially the development of the agrarian sector according to the Common Agricultural Policy, CAP until 2015 including supplementary measures and other impact factors has been analysed. The impact of this so-called baseline scenario 2015 was predicted for both, the diffuse N surpluses and the N pollution of groundwater and surface waters. It could be shown that the baseline projections for the agricultural sector through 2015 may lead to decrease of the diffuse N inputs into groundwater by ca. 13.500 t???a^?1?N and an overall decrease of the diffuse N inputs into surface waters by ca. 25.000 kg???ha^?1???a^?1?N. Based on the baseline scenario 2015 the additional N reduction to guarantee nitrate concentrations in groundwater below the EU-threshold value of 50 mg???l^?1 NO₃ was determined by means of a backward model calculation. This was done using the predicted nitrate concentrations in the leachate 2015 for the individual 100 m???100 m grids as starting points. In this way for the whole territory of NRW an additional N reduction beyond the baseline scenario 2015 of ca. 12.000 t???a^?1?N has been assessed. Model results indicate that additional N reduction measures don’t have to be implemented area-covering in order to be efficient, but in certain subareas only. It is suggested that in these subareas the available financial resources for the implementation of N reduction measures shall be used for individual, i.e. regionally adapted nitrate reduction measures.     

Comparing two types of engineering visualizations: task-related manipulations matter

This study focuses on the comparison of traditional engineering drawings with a CAD (computer aided design) visualization in terms of user performance and eye movements in an applied context. Twenty-five students of mechanical engineering completed search tasks for measures in two distinct depictions of a car engine component (engineering drawing vs. CAD model). Besides spatial dimensionality, the display types most notably differed in terms of information layout, access and interaction options. The CAD visualization yielded better performance, if users directly manipulated the object, but was inferior, if employed in a conventional static manner, i.e. inspecting only predefined views. An additional eye movement analysis revealed longer fixation durations and a stronger increase of task-relevant fixations over time when interacting with the CAD visualization. This suggests a more focused extraction and filtering of information. We conclude that the three-dimensional CAD visualization can be advantageous if its ability to manipulate is used.     

Generic integration of content-based image retrieval in computer-aided diagnosis

Content-based image retrieval (CBIR) offers approved benefits for computer-aided diagnosis (CAD), but is still not well established in radiological routine yet. An essential factor is the integration gap between CBIR systems and clinical information systems. The international initiative Integrating the Healthcare Enterprise (IHE) aims at improving interoperability of medical computer systems. We took into account deficiencies in IHE compliance of current picture archiving and communication systems (PACS), and developed an intermediate integration scheme based on the IHE post-processing workflow integration profile (PWF) adapted to CBIR in CAD. The Image Retrieval in Medical Applications (IRMA) framework was used to apply our integration scheme exemplarily, resulting in the application called IRMAcon. The novel IRMAcon scheme provides a generic, convenient and reliable integration of CBIR systems into clinical systems and workflows. Based on the IHE PWF and designed to grow at a pace with the IHE compliance of the particular PACS, it provides sustainability and fosters CBIR in CAD.     

Dimensions of Employee Satisfaction as Determinants of Organizational Commitment in the Hotel Industry

In today's dynamic environment, the role of employees and their level of organizational commitment are becoming increasingly important for business success, which is especially relevant for the service industry in general and for the tourism sector in particular because of problems associated with employee turnover, loyalty strategies with the customer, and so forth. Employee satisfaction is considered an essential ingredient for developing organizational commitment. The main purpose of this study is to analyze the influence of different facets of employee job satisfaction, that is, job conditions, reward system, relations with superiors and co‐workers, organizational human resources (HR) policies, on employees’ organizational commitment in the hotel industry. The research hypotheses are tested with a sample of 760 hotel employees on Gran Canaria, Spain. The results show the relevance of the working conditions, direct rewards, relationships with managers, and the HR policies in order to develop a high level of organizational commitment.     

Functional attributes of the landscape surrounding the Temelin nuclear power plant (Czech Republic)

The aim of this study is to show the importance of permanent vegetation in landscape in terms of surface temperature. Indicators of key landscape functions (surface temperature, wetness, and biomass content) were monitored from May to September in five catchments with different vegetation covers. The analysis of Landsat satellite data illustrates that areas with a higher proportion of forest and wetlands provide a more balanced temperature–moisture regime throughout the growing season, reduce average and peak temperature, and enhance humidity. In these areas, solar radiation is transformed into latent heat, which leads to landscape cooling. This process indirectly leads to the reduction of soil erosion, loss of water, oxidation of organic matter, and nutrient export. A landscape characterized by a balanced temperature–moisture regime also has a higher ability to bind and retain pollutants. Artificial drainage and loss of natural wetlands are common across most of our agricultural landscapes. Drained fields have a low capacity to retain water, nutrients, and pollutants. Where cereal crops dominate, the temperature–moisture regime evolves through different stages. With the exception of the early growth, maturity and senescence are characterized by high average and peak temperatures, high temperature variations, and low humidity. As illustrated by the relationship existing between water electrical conductivity and cation concentration in relation to land cover, such landscapes have a lowered ability to retain chemical elements and pollutants. The sites that were object of our survey are situated within the emergency planning zone of the Temelín nuclear power plant, in order to demonstrate how our analytical approach may be applied to radiation risk management.     

On weighted balls-into-bins games

We consider the well-known problem of randomly allocating m$m$ balls into n$n$ bins. We investigate various properties of single-choice games as well as multiple-choice games in the context of weighted balls. We are particularly interested in questions that are concerned with the distribution of ball weights, and the order in which balls are allocated. Do any of these parameters influence the maximum expected load of any bin, and if yes, then how?     

Design und Herstellung selektiver Dünnschichtabsorber auf Silberinselbasis. Design and fabrication of selective multilayer absorber based on silver island films

The combination of a metal island film with a dielectric multilayer represents a novel approach for preparation of spectrally selective absorbers. Metal island films show exceptional optical properties caused by the optical excitation of surface plasmon modes. The plasmon resonance frequency depends on the size and shape of the islands and is influenced by the deposition parameters. The first type of samples represents a silver island film in an ultra thin Al₂O₃ film. We analyzed these samples by means of spectrophotometry. The recorded spectra allow the calculation of the optical constants of the silver island films. These show a maximum absorptance up to 40 %. Finally, we incorporated ultrathin metal‐dielectric‐composite films on a silver/alumina basis into multilayer stacks to design tailored spectrally selective absorber coatings. The stack absorptance comes close to 100 %.     

Inserting an Edge into a Planar Graph

Computing a crossing minimum drawing of a given planar graph G augmented by an additional edge e where all crossings involve e, has been a long standing open problem in graph drawing. Alternatively, the problem can be stated as finding a combinatorial embedding of a planar graph G where the given edge e can be inserted with the minimum number of crossings. Many problems concerned with the optimization over the set of all combinatorial embeddings of a planar graph turned out to be NP-hard. Surprisingly, we found a conceptually simple linear time algorithm based on SPQR-trees, that is able to find a solution with the minimum number of crossings.