Uncertainties in the fate of nitrogen I: An overview of sources of uncertainty illustrated with a Dutch case study

This study focuses on the uncertainties in the fate of nitrogen (N) in the Netherlands. Nitrogen inputs into the Netherlands in products, by rivers, and by atmospheric deposition, and microbial and industrial fixation of atmospheric N₂ amount to about 4450 Gg N y^–1. About 60% of this N is transported out of the Netherlands in products. The fate of the remaining 40%, however, is less clear. We discuss uncertainties in losses to the atmosphere (as ammonia or through denitrification), by leaching and runoff, and in N accumulation in biomass and soils. These processes may account for the fate of about 40% of the N in the Netherlands, and for the fate of about 60% of the N in Dutch agricultural soils. Reducing uncertainties in the estimates of these fluxes is necessary for reducing the impact of excess N in the environment. In particular, monitoring the environmental effects of ammonia emissions and nitrate leaching to groundwater and aquatic systems requires an increased understanding of the fate of N. Uncertainties arise because (1) some N fluxes cannot be measured directly and are usually quantified indirectly as the balance in N budgets, (2) direct measurements of N fluxes have inevitable inaccuracies, (3) lack of experimental data and other information (e.g. statistics) needed for upscaling, (4) large spatial and temporal variability of fluxes, and (5) poor understanding of the processes involved. These uncertainties can be reduced by additional experimental studies and by further development of process-based models and N budget studies. We prioritize these future research needs according to a range of different criteria.     

A web-based platform for virtual screening

A fully integrated, web-based, virtual screening platform has been developed to allow rapid virtual screening of large numbers of compounds. ORACLE is used to store information at all stages of the process. The system includes a large database of historical compounds from high throughput screenings (HTS) chemical suppliers, ATLAS, containing over 3.1 million unique compounds with their associated physiochemical properties (ClogP, MW, etc.). The database can be screened using a web-based interface to produce compound subsets for virtual screening or virtual library (VL) enumeration. In order to carry out the latter task within ORACLE a reaction data cartridge has been developed. Virtual libraries can be enumerated rapidly using the web-based interface to the cartridge. The compound subsets can be seamlessly submitted for virtual screening experiments, and the results can be viewed via another web-based interface allowing ad hoc querying of the virtual screening data stored in ORACLE.     

A toolset for building the virtual enterprise

Much research has been undertaken to define what a virtual enterprise is and how it should work. This paper addresses the specific question, how a virtual enterprise can be designed to have the agility to support short-term business opportunities. A framework is presented for the organizational design and the changing business roles of the business architect who constructs the various phases of the virtual enterprises lifecycle. This infrastructure for creating virtual enterprises is referred to as the value system designer; a set of methods and tools to select partners, re-engineer business- and logistic processes and to set up an information and communication platform for the virtual enterprise. The methods and tools have been developed in two longitudial research projects TELEflow and the Virtuelle Fabrik between 1995 and 1999. Focusing on the experiences gained from numerous cases, a summary on crucial success factors for designing virtual enterprises shall be presented. Thus, this paper gives insights and applicable know-how for companies and managing engineers in their role as virtual enterprise architects, for example leaders of project consortia or joint ventures or as first-tier suppliers co-ordinating supplier (sub-) nets.     

Novel lipidic enaminones from a C18 keto-allenic ester

Primary amines (ammonia, methyl, propyl, octyl, octadecyl, phenyl, benzyl, phenethyl) including methyl esters of amino acids (glycine, dl-alanine, l-valine, l-leucine, L-tyrosine, and l-methionine), and secondary amines (dimethyl, diethyl, dipropyl, diisopropyl, dioctyl, and diphenyl) attack regiospecifically the central carbon atom of the allene system of methyl 12-keto-9,10-octadecadienoate (1) to give the corresponding lipidic enaminone derivatives (2–21) with an average yield of 77%. The E- and Z-configuration of the enaminone system of these novel lipid derivatives was confirmed by infrared and nuclear magnetic resonance spectroscopic techniques. Primary amines furnished Z-enaminones, while secondary amines gave E-enaminones.     

Model-based evaluation of clustering validation measures

A cluster operator takes a set of data points and partitions the points into clusters (subsets). As with any scientific model, the scientific content of a cluster operator lies in its ability to predict results. This ability is measured by its error rate relative to cluster formation. To estimate the error of a cluster operator, a sample of point sets is generated, the algorithm is applied to each point set and the clusters evaluated relative to the known partition according to the distributions, and then the errors are averaged over the point sets composing the sample. Many validity measures have been proposed for evaluating clustering results based on a single realization of the random-point-set process. In this paper we consider a number of proposed validity measures and we examine how well they correlate with error rates across a number of clustering algorithms and random-point-set models. Validity measures fall broadly into three classes: internal validation is based on calculating properties of the resulting clusters; relative validation is based on comparisons of partitions generated by the same algorithm with different parameters or different subsets of the data; and external validation compares the partition generated by the clustering algorithm and a given partition of the data. To quantify the degree of similarity between the validation indices and the clustering errors, we use Kendall's rank correlation between their values. Our results indicate that, overall, the performance of validity indices is highly variable. For complex models or when a clustering algorithm yields complex clusters, both the internal and relative indices fail to predict the error of the algorithm. Some external indices appear to perform well, whereas others do not. We conclude that one should not put much faith in a validity score unless there is evidence, either in terms of sufficient data for model estimation or prior model knowledge, that a validity measure is well-correlated to the error rate of the clustering algorithm.     

Practical Anisotropic Geodesy

The computation of intrinsic, geodesic distances and geodesic paths on surfaces is a fundamental low‐level building block in countless Computer Graphics and Geometry Processing applications. This demand led to the development of numerous algorithms – some for the exact, others for the approximative computation, some focussing on speed, others providing strict guarantees. Most of these methods are designed for computing distances according to the standard Riemannian metric induced by the surface's embedding in Euclidean space. Generalization to other, especially anisotropic, metrics – which more recently gained interest in several application areas – is not rarely hampered by fundamental problems. We explore and discuss possibilities for the generalization and extension of well‐known methods to the anisotropic case, evaluate their relative performance in terms of accuracy and speed, and propose a novel algorithm, the Short‐Term Vector Dijkstra. This algorithm is strikingly simple to implement and proves to provide practical accuracy at a higher speed than generalized previous methods.     

A cognitive-behavioral model of problematic online gaming in adolescents aged 12–22 years

The aim of this study was to apply the cognitive behavioral model of problematic Internet use to the context of online game use to obtain a better understanding of problematic use of online games and its negative consequences. In total, 597 online game playing adolescents aged 12–22 years participated in this study. Results showed that the cognitive behavioral model of problematic Internet use can also be used in the context of online game use. More specifically, preference for online social interaction, mood regulation and deficient self-regulation appeared to play an important role in predicting negative outcomes from problematic online game use. Together, these cognitions and behaviors explained 79% of the variance of negative outcomes scores. These findings can be used to develop strategies that aim at reducing problematic online game behavior and its negative consequences.     

Fault recoverability analysis of switched systems

This article provides an approach to evaluate the fault recoverability of switched systems (SS) under given energetic constraints. Such evaluation reveals the capability of the SS to tolerate the worst faults over a prescribed set under possible energy constraints. The evaluation is achieved by using the smallest eigenvalue of a proposed ‘switched-system controllability Gramian’. Simulation results about a longitudinal flight control process example are presented to show the effectiveness of the proposed method.     

Investigating the ESBWR stability with experimental and numerical tools: A comparative study

In this work, the stability of the Economic Simplified Boiling Water Reactor (ESBWR) has been studied by using a Freon-134a based experimental facility (GENESIS) and two system codes, being ATHLET 2.0a and (to a lesser extent) TRACG. During setting up the GENESIS facility and the numerical calculations, a great effort has been made to approximate the ESBWR system as accurate as possible.In general, it was found that a sufficient margin to instability exists regarding the ESBWRs nominal point. In addition, a comparison was made between the numerical and experimental results for both the thermal-hydraulic system and the reactor system. Deviations were found between the numerical and experimental results, in spite of the close similarity between the GENESIS facility and the definition of the ESBWR system in the system code. This result shows that predictions regarding real nuclear reactors, based on modeled systems, should be taken with care.     

Resilient, overcontrolled, and undercontroleed personality prototypes in childhood: Replicability, predictive power, and the trait-type issue.

In a longitudinal study, Q-sort patterns of German preschool children were analyzed for personality prototypes and related to developmental outcomes up to age 12. Q-factor analyses confirmed 3 prototypic patterns that showed a high continuity and cross-judge consistency; were similar to those found for North American, Dutch, and Icelandic children; and can be interpreted as resilient, overcontrolled, and undercontrolled. Relations reported by R. W. Robins, O. P. John, A. Caspi, T. E. Moffitt, & M. Stouthamer-Loeber (1996) between these 3 patterns and the Big Five were fully replicated. Growth curve analyses showed that the 3 patterns predicted important developmental outcomes in both the social and the cognitive domains. Evidence was found for both traits and types: A continuous dimension of resiliency bifurcates in its lower part into two relatively discrete personality types, overcontrollers and undercontrollers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)