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Research in the past decades repeatedly revealed university students' struggles to properly understand physical chemistry concepts. In contrast to school, tertiary teaching relies heavily on the symbolic level, mainly applying abstract representations such as equations and diagrams. To follow the lessons and generate conceptual understanding, students need to connect those representations with macroscopic and submicroscopic aspects of the scientific concept depicted. For German first-year chemistry students, this increase in abstraction in a major subject of study contributes to excessive demand and demotivation (especially during out-of-class learning) and increases the risk of early dropouts. We designed a simulation-based learning environment (BIRC: Bridging Imagination and Representation in Chemistry) to suit the needs of first-year students and support them when learning physical chemistry at home. Our approach, featuring molecular dynamics simulations, requires students to assess their own mental models on the submicroscopic level and connect them to equations and diagrams on the symbolic level. Prior studies did already highlight the potential of individual BIRC learning units to foster conceptual understanding on specific topics. In this paper, we investigate if and how students of a broader sample use these learning activities as voluntary supplement beside regular coursework. During the term, we used think-aloud protocols, interviews and eight online questionnaires to analyse students' mental and emotional interaction while working on BIRC, assessing whether students perceived BIRC as a suitable, enjoyable and supportive resource to enhance learning. Via two paper & pencil achievement tests we examined students' retention concerning submicroscopic mental models and their ability to connect these mental models with symbolic representations 5-10 weeks later. Our findings indicate a cognitively engaging, comparably enjoyable learning process, which strengthens conceptual understanding and -- despite the necessary time and effort -- induces a broad number of students to voluntarily work on several units at home.

Avatar-based virtual reality (VR) is becoming more prevalent in industry and educational settings. There is, however, limited research on the extent to which gender stereotypes are present in this environment. The university laboratory study presented in this paper was conducted in a VR environment with participants who were randomly assigned to male or female avatars and instructed to negotiate the role of a manager or member of staff. The results reveal differences in satisfaction regarding their roles and gender. Participants who embodied a female avatar were less happy when they were subordinates interacting with a male avatar, compared to participants embodying a male avatar in the staff role (interacting with a female avatar). Male avatars with staff roles were also more content with their avatar than male avatars with manager roles and also reported being more comfortable in the VR experience. Relevant for diversity management when integrating VR in education and business, the results are discussed in regard to self-similarity and social identity dynamics and provide insight into understanding the extent to which gender stereotypes may be present in avatar-based VR.

Addressing the problems of bullying in schools, this paper presents a novel and highly innovative pedagogical approach, building on the immersive power of virtual role-play. Educational role-play is widely accepted as a powerful instrument to change attitudes and behaviour, but faces some difficulties and disadvantages when applied to sensitive social issues in the classroom. This paper shows how the FearNot! software application, developed within the scope of the EU-funded projects VICTEC (Virtual ICT with Empathic Characters) and eCIRCUS (Education through Characters with emotional-Intelligence and Role-playing Capabilities that Understand Social interaction) uses virtual role-play and autonomous agents to provide children aged eight to eleven years of age with the opportunity to visit a virtual school environment populated by 3D animated synthetic characters that engage in bullying episodes. The characters' actions and the storyline are created as improvised dramas by use of emergent narrative, resulting in unscripted and highly believable interaction experiences for the learner. While the students are spectators to the bullying episodes that unfold among the FearNot! characters, the victimised character starts a conversation with the student in between the episodes, describing their experiences with bullying and how they feel as a result to it, and asking the student for advice. The aim of this approach and particularly of this interaction sequence in between the virtual bullying episodes is to sensitise primary school students to the potential problems that victims of persistent aggressive behaviour are facing: By triggering an empathic relationship between learners and characters, learners understand and vicariously feel into the plight of the victimised character. Empirical evidence from bullying research implies that bullies are regularly reinforced by bystanders that witness the bullying and turn their attention to it, but do not actively intervene to end it (Craig & Pepler 1996; Lean 1998; Salmivalli 1999; Hawkins et al. 2001). Hence, this intervention strategy targets these bystanders to stand up to the bully and help the victim, due to their heightened awareness and sensitivity to the grave consequences victims face. Preliminary evaluation results indicate that the children were willing to immerse themselves in the virtual drama and that they empathically engage with the characters, attributing a range of emotions to the characters depending on the events that happen within the respective scenario. An ongoing long-term intervention in school in the UK and Germany covers several interactions with the software over a ten week period of time.

Games have been successfully used in educational settings for many years. Still, it is not known in detail which factors influence the use and effectiveness of educational games. The game environment, its technology, and other game mechanics are factors directly linked to the game itself. The player's experience with the subject of the game and/or games in general, his or her motivation and expectations towards the gaming experience influence the outcome of a game-based learning experience. Some of the personal aspects, like age, were already addressed in earlier research. Cultural and gender differences though, were not a main object of study in educational gaming so far. This study started from certain assumptions about differences in game play, related to players' cultural backgrounds and gender. Literature suggests that gender plays a role when it comes to game performance. This paper introduces outcomes of a study with a so-called Microgame, a brief game used to raise the awareness of interdependent planning operations. It shows that in this game, gender and culture make a difference in relation to the learning experience of the players, measured by game performance.

Simulations and virtual or remote laboratories are increasingly used in schools. The extent to which individual experimental skills can be acquired when experimenting in digital applications is, however, questionable. This paper focuses on finding multimedia features for digital experiments to support the transfer of measured values from the laboratory system to a diagram. Beside physical considerations, spatial translation processes could be crucial for a successful assignment. Therefore, the influence of the subjects' spatial ability is examined. Using a pretest post-test design (N = 119), the effects of training with supportive animation (animation group) and training with an interactive task and feedback (interactive group) were tested. The results of both groups were each compared to those of a reference group. Eye tracking data were recorded during training to investigate the origin of different training effects. Hence, fixations and saccades during training were analyzed. For the investigation of the distribution of the saccadic movements, polar diagrams were used in combination with estimated probability density functions. The results show that the score in the pretest is correlated to the score achieved in the card rotation test, which measures the spatial rotation skills of the subjects. Further, the subjects in the interactive group benefited from the training more than the subjects in the reference group did. There were no significant differences in the effect of the training between the animation group and the reference group. Eye tracking data reveal that the training in the interactive group caused the most comparative eye movements between the laboratory system and the diagram. The training in the animation group led to the highest visual attention; however, subjects in this group concentrated on the dynamic elements. These results indicate that especially students with weak spatial skills need additional support when transferring measured values from the laboratory system to the diagram. This assignment can be practiced in computer-based experiments, in particular with an interactive training task and feedback. Additionally, the analysis showed that the training is equally suitable for learners with different spatial abilities. A corresponding task was implemented into a virtual laboratory.

In this paper, the authors reviewed the empirical augmented reality (AR) and online education studies, and those focused on designing or development of AR to help students learn, published in SSCI, SCI-EXPANDED, and A&HCI journals from 2003 to 2012. The authors in this study found that the number of AR and online education studies has significantly increased since 2009. Based on this review, it is found that contributors from Spain, Romania, Taiwan, and Germany had the most publications on AR and online education during 2003 to 2012. Moreover, the analysis of these selected papers reveals that most empirical AR and online education studies were conducted at universities, as well as in computer science courses. Furthermore, the quantitative research method was used more in the reviewed papers. The findings and analysis from this review may provide potential directions and insights for future AR and online education research.

This paper aims to contribute to the growing literature on how prospective foreign language teachers can learn to be successful telecollaborators. We investigate Polish and German TEFL students' perceptions of how they develop the competences, attitudes, and beliefs described by O'Dowd (2015) through experiential learning in a virtual exchange. Using grounded theory as its research methodology, our study used data from three different sources: (a) a pre- and post-project survey investigating students' changing perceptions of the relevance of telecollaboratively taught classes for their professional and personal development, (b) a survey and ethnographic observation focusing on students' perceptions of and attitudes toward distributed teaching presence in the exchange project (cf. Turula & Grau, 2018), and (c) a case study employing a survey and a semi-structured interview with a participant who carried out her own telecollaborative project in a primary school. The necessarily tentative results of this small-scale investigation point toward the suitability of the experiential learning approach for the development of organisational, digital, and pedagogical telecollaborative competences, potentially shaping prospective teachers' attitudes and beliefs.

This paper presents a web-based education platform for the visualization and animation of the digital logic design process. This includes the design of combinatorial circuits using logic gates, multiplexers, decoders, and look-up-tables as well as the design of finite state machines. Various configurations of finite state machines can be selected to define the machine type, the state code, and the flip-flop type. Logic minimization with the K-map approach and the Quine McCluskey scheme is also supported. The tools, denoted as DLD-VISU, help students practice related topics in digital logic design courses. Also, instructors can use the tools to efficiently generate and verify examples for lecture notes or for homework problems and assignments. DLD-VISU was designed relying on a thorough investigation of related pedagogical aspects to define appropriate interactive graphical processes. The decision for a web-based solution, on the one hand, was motivated by making the tools available, portable, expandable, and at the same time transparent to the user. On the other hand, the advocated approach enables instructors to define access rules for their students to assure that students cannot use the tools to solve assessed homework problems or assignments before submission deadline. DLD-VISU supports self-assessment and reflects the student learning process using learning curves. The proposed platform was evaluated both in form of students' feedback as well as by analyzing the impact of using the tools on students' performance.

Currently not many people would doubt that computers play an essential role in both public and private life in many countries. However, somewhat surprisingly, evidence of computer use is difficult to find in German state schools although other countries have managed to implement computer-based teaching and learning in their schools. This paper attempts to understand the reasons for this phenomenon and to show that more research and development on computer-based teaching and learning should be done. It starts with some comments on the importance of computer-based learning, followed by a description of the development of ICT in education since the 1990s in Germany and the general situation at public schools. After focusing on the frame of educational policy in Germany, the situation in schools, including the person of the teacher, is then reflected upon and compared to the situation in other countries. Finally, current developments of computer-based learning in chemistry education in Germany are discussed and a frame of further research is proposed.

In this paper, an experimental and numerical investigation of the effect of leading-edge erosion in transonic blades was performed. The measurements were carried out on a linear blade cascade in the Transonic Cascade Wind Tunnel of DLR in Cologne at two operating points with an inflow Mach number of 1.05 and 1.12. The numerical simulations were performed by ANSYS Germany. The type and specifications of the erosion for the study were derived from real engine blades and applied to the leading edges of the experimental cascade blades using a waterjet process, as well as modeled in detail and meshed within the numerical setup. Numerical simulations and extensive wake measurements were carried out on the cascades to evaluate the aerodynamic performance. The increase in losses was quantified to be 4 percent, and a reduction in deflection and a rise in pressure were detected at both operating points. [ABSTRACT FROM AUTHOR]

Over the past decade, industry relevance and connectedness have evolved into a key requirement for students and their parents, who increasingly perceive employability upon graduation as a critical factor in the degree selection process. Simultaneously, professional bodies emphasise the need for high levels of industry engagement as a condition for accreditation, which in turn further impacts on the "marketability" of a specific degree. However, many of the skills emphasised by potential employers and industry reference groups are more closely aligned with generic graduate attributes, rather than discipline specific knowledge and skills. This increasingly includes an emphasis on cultural awareness, excellent communication skills and the ability to work in dispersed, often even virtual teams. This observation is arguably particularly relevant within the business (degree) context, where workforces become increasingly multicultural, as traditional borders and limitations make way for transnational opportunities. This paper discusses the benefits and challenges associated with a third year student project that set out to combine the need for discipline specific knowledge, with the acquisition of versatile, culturally sensitive business skills. Students participating in the aptly titled "communications challenge" competed against their peers as part of multicultural teams, representing twelve countries, across five continents. The authors conclude that experiential learning opportunities like this global, real life client project may not necessarily be popular amongst the wider student cohort. Furthermore, the acquisition of discipline specific knowledge may be limited when compared to "traditional" teaching deliveries. However, projects like this provide a number of benefits, in particular in the context of capstone units that set out to prepare students for a diverse career in an increasingly global, multicultural and complex environment.

Bullying is widespread in European schools, despite multiple intervention strategies having been proposed over the years. The present study investigates the effects of a novel virtual learning strategy ("FearNot!") to tackle bullying in both UK and German samples. The approach is intended primarily for victims to increase their coping skills and further to heighten empathy and defence of victims by non-involved bystanders. This paper focuses on the defender role. Applying quantitative as well as qualitative methodology, the present study found that "FearNot!" helped non-involved children to become defenders in the German sub-sample while it had no such effect in the UK sub-sample. German "New Defenders" (children who are initially uninvolved but are nominated as defenders by their peers after the intervention period) were found to be significantly more popular at baseline, and to show more cognitive empathy (Theory of Mind) for the virtual victims as compared to permanently non-involved pupils. Moreover, gender interacts with becoming a defender in its effects on affective empathy, with emotional contagion being particularly associated with New Defender status among girls. The findings are discussed in relation to previous research on anti-bullying intervention strategies and cultural differences in bullying prevalence rates and intervention outcomes.

In the present paper, the fracture toughness of a polyurethane (PUR) foam (manufactured by Necumer GmbH, Germany, under the commercial designation Necuron 651) is experimentally and numerically investigated in order to examine its dependence on the specimen sizes. As a matter fact, to the best knowledge of the present authors, such an analysis is still missing in the technical literature. To perform the experimental campaign, notched PUR foam beams, with different geometrical sizes, are tested under three‐point bending loading, and the Modified Two‐Parameter Model (recently proposed by some of the present authors) is employed to measure the fracture toughness. Subsequently, such an experimental campaign is numerically simulated by applying a micromechanical model, implemented in a non‐linear finite element homemade code. Finally, the results obtained are compared with some experimental data available in the literature, related to the same PUR foam. Highlights: The fracture toughness of a polyurethane foam is experimentally investigated.Notched PUR foam beams, with different sizes, are tested under three‐point bending.The Modified Two‐Parameter Model is employed to measure the fracture toughness.A numerical simulation is performed with a non‐linear finite element model.The results are compared with some experimental data available in the literature. [ABSTRACT FROM AUTHOR]

Temporally and spatially resolved data on wind power generation are very useful for studying the technical and economic aspects of this variable renewable energy at local and regional levels. Due to the lack of disaggregated electricity data from onshore and offshore turbines in Germany, it is necessary to use numerical simulations to calculate the power generation for a given geographic area and time period. This study shows how such a simulation model, which uses freely available plant and weather data as input variables, can be developed with the help of basic atmospheric laws and specific power curves of wind turbines. The wind power model is then applied to ensembles of nearly 28,000 onshore and 1500 offshore turbines to simulate the wind power generation in Germany for the years 2019 and 2020. For both periods, the obtained and spatially aggregated time series are in good agreement with the measured feed-in patterns for the whole of Germany. Such disaggregated simulation results can be used to analyze the power generation at any spatial scale, as each turbine is simulated separately with its location and technical parameters. This paper also presents the daily resolved wind power generation and associated indicators at the federal state level. [ABSTRACT FROM AUTHOR]

Background: Innovative educational approaches such as simulation-based nursing education using virtual reality (VR) technologies provide new opportunities for nursing education. However, there is a lack of information on side effects, especially health-related side effects, of head-mounted displays (HMDs) on the human body when using VR devices for nursing simulation. This study aims to validate the German version of the Virtual Reality Sickness Questionnaire (VRSQ) and to evaluate its associations with sex and age, as reflected in the VRSQG scores (total score, oculomotor, and disorientation) over time. Methods: A longitudinal-sectional study was conducted. In addition to the VRSQG (pre-, post-, and 20 min post-intervention), participants (all nursing students) completed data on personal characteristics. Participants completed a VR simulation of a blood draw. Confirmatory factor analysis (CFA) was used to evaluate whether the measured construct was consistent with the original. In addition to the validity, internal consistency was analyzed and generalized linear models (GLMs) were used for data analysis. Results: A total of 38 nursing students (mean age 26.8 years; SD = 7.1, 79.0% female) participated. The mean time spent in the VR simulation was 21 min. All participants completed the entire simulation. The CFA indicates (CFI = 0.981, SRMR = 0.040) VRSQG structure is given. Internal consistency showed low values for the subdomain Oculomotor (Cronbach alpha 0.670). For Disorientation and the Total score values showed a sufficient internal consistency. GLMs showed significant between subject associations with age over time with VRSQG total score, oculomotor, and disorientation. Older nursing students start with higher VRSQG-Scores. Over time, an approximation occurs, so that all participants reach a similar level by the final measurement point. No associations were found between sex (male/female) and VRSQG scores. Conclusions: The VRSQG is a reliable and valid self-assessment for measuring cybersickness in VR based nursing simulations, with cybersickness symptoms positively associated with age. However, in depth-evaluation regarding age-associations with cybersickness should be done. As well as studies to explore additional associations and emphasizes the importance of establishing cut-off values to assess the clinical relevance of the scores. [ABSTRACT FROM AUTHOR]

This paper presents research activities associated with the development of a simulation tool for modelling human reliability in production systems. This dynamic model enables the planner to determine the consequences of changes in human reliability on the quality of the production processes and the products. The model is built upon the basis of a tool for human reliability analysis ESAT (Experten-System zur Aufgaben-Taxonomie; Aufgabentaxonomie: Ein Verfahren zur Ermittlung der menschlichen Leistung bei der Durchführung von Aufgaben, Messerschmitt-Bölkow-Blohm, Ottobrunn, 1990.) and a personnel-oriented simulation programme ESPE (Engpassorientierte Simulation von Personalstrukturen; Ein engpassorientierter Ansatz zur simulationsunterstützten Planung von Personalstrukturen, Dissertation, Karlsruhe University, 1994), developed at the ifab-Institute of Human and Industrial Engineering at the University of Karlsruhe. In addition to the definition and the calculation of the human error probabilities, the consequences of the human errors (i.e. rework and waste) for the quality of the processes and the products were also implemented. This method is able to systematically plan quality-oriented assignments of personnel to functions and workplaces (personnel structures) in production systems. The effectiveness of the method is demonstrated by a case study.

In case of large data matrices comparative evaluations of objects/regions with the technique of Hasse diagrams may be troublesome due to a messy system of lines in the graphical representation. Here fuzzy clustering leads to useful simplifications because regions with slightly different pollution pattern are grouped together. However, fuzzy clustering implies to introduce a threshold value for the membership of an object to a cluster and to select the best number of clusters. Therefore many arbitrarities evolve. Within the systematic study presented here we found that some objects are very stable against variations of the threshold value and the number of cluster whereas other objects behaves different. According to their behaviour we investigated a classification of the objects. Formal Concept Analysis shows that in some cases specific pollution pattern imply the membership to one of these classes. For example objects which are characterized by high Pb-, Zn-concentration and moderate S-concentration imply a high stability against variants of the clustering process. Further implications are described in the paper.

In flood modeling, many 1D and 2D combination and 2D models are used to simulate diversion of water from rivers through dyke breaches into the hinterland for extreme flood events. However, these models are too demanding in data requirements and computational resources which is an important consideration when uncertainty analysis using Monte Carlo techniques is used to complement the modeling exercise. The goal of this paper is to show the development of a quasi-2D modeling approach, which still calculates the dynamic wave in 1D but the discretisation of the computational units are in 2D, allowing a better spatial representation of the flow in the hinterland due to dyke breaching without a large additional expenditure on data preprocessing and computational time. A 2D representation of the flow and velocity fields is required to model sediment and micro-pollutant transport. The model DYNHYD (1D hydrodynamics) from theWASP5 modeling package was used as a basis for the simulations. The model was extended to incorporate the quasi-2D approach and a Monte-Carlo Analysis was used to conduct a flood sensitivity analysis to determine the sensitivity of parameters and boundary conditions to the resulting water flow. An extreme flood event on the Elbe River, Germany, with a possible dyke breach area was used as a test case. The results show a good similarity with those obtained from another 1D/2D modeling study. [ABSTRACT FROM AUTHOR]

After the extreme flood event of the Elbe in 2002 the definition of flood risk areas by law and their simulation became more important in Germany. This paper describes a concept of an analysis framework to improve the localisation and duration of validity of flood inundation maps. The two-dimensional finite difference model TrimR2D is used and linked to a Monte-Carlo routine for parameter sampling as well as to selected performance measures. The purpose is the investigation of the impact of different spatial resolutions and the influence of changing land uses in the simulation of flood inundation areas. The technical assembling of the framework is realised and beside the model calibration, first tests with different parameter ranges were done. Preliminary results show good correlations with observed data, but the investigation of shifting land uses reflects only poor changes in the flood extension. [ABSTRACT FROM AUTHOR]

Background: Simulation models play an increasingly important role in tobacco control. Models examining the impact of nicotine vaping products (NVPs) and smoking tend to be highly specialized and inaccessible. We present the Smoking and Vaping Model (SAVM),a user-friendly cohort-based simulation model, adaptable to any country, that projects the public health impact of smokers switching to NVPs. Methods: SAVM compares two scenarios. The No-NVP scenario projects smoking rates in the absence of NVPs using population projections, deaths rates, life expectancy, and smoking prevalence. The NVP scenario models vaping prevalence and its impact on smoking once NVPs became popular. NVP use impact is estimated as the difference in smoking- and vaping-attributable deaths (SVADs) and life-years lost (LYLs) between the No-NVP and NVP scenarios. We illustrate SAVM's adaptation to the German adult ages 18+ population, the Germany-SAVM by adjusting the model using population, mortality, smoking and NVP use data. Results: Assuming that the excess NVP mortality risk is 5% that of smoking, Germany-SAVM projected 4.7 million LYLs and almost 300,000 SVADs averted associated with NVP use from 2012 to 2060. Increasing the excess NVP mortality risk to 40% with other rates constant resulted in averted 2.8 million LYLs and 200,000 SVADs during the same period. Conclusions: SAVM enables non-modelers, policymakers, and other stakeholders to analyze the potential population health effects of NVP use and public health interventions. [ABSTRACT FROM AUTHOR]

Abstract: In this paper fluid–structure interaction simulations regarding a gust generator experiment are presented, which has been conducted in 2010 in the Transonic Wind Tunnel in Göttingen (DNW-TWG), Germany. The main objective of the experiment was the investigation of the dynamic response problem of an elastic wing model concerning an encountering generic gust induced by a gust generator. Fluid–structure simulations, using a finite element structural model and a computational fluid dynamics model based on time-accurate, Reynolds-averaged Navier–Stokes equations, are compared to the experiment to validate the numerical methodology. Comparisons include steady and unsteady deflections of the elastic wing and pressure distributions. Finally, the results of simulated transfer functions of the gust generator to the elastic wing are presented in comparison to the test data. [Copyright &y& Elsevier]

Abstract: Both modelers and social scientists attempt to find better explanations of complex urban systems. They include development paths, underlying driving forces and their expected impacts. So far, land-use research has predominantly focused on urban growth. However, new challenges have arisen since urban shrinkage entered the research agenda of the social and land-use sciences. Therefore, the focus of this paper is a twofold one: Using the example of urban shrinkage, we first discuss the capacity of existing land-use modeling approaches to integrate new social science knowledge in terms of land-use, demography and governance because social science models are indispensable for accurately explaining the processes behind shrinkage. Second, we discuss the combination of system dynamics (SD), cellular automata (CA) and agent-based model (ABM) approaches to cover the main characteristics, processes and patterns of urban shrinkage. Using Leipzig, Germany, as a case study, we provide the initial results of a joint SD-CA model and an ABM that both operationalize social science knowledge regarding urban shrinkage. [Copyright &y& Elsevier]

Intense heavy ion beams offer a unique tool for generating samples of high energy density matter with extreme conditions of density and pressure that are believed to exist in the interiors of giant planets. An international accelerator facility named FAIR (Facility for Antiprotons and Ion Research) is being constructed at Darmstadt, which will be completed around the year 2015. It is expected that this accelerator facility will deliver a bunched uranium beam with an intensity of 5×1011 ions per spill with a bunch length of 50-100 ns. An experiment named LAPLAS (Laboratory Planetary Sciences) has been proposed to achieve a low-entropy compression of a sample material like hydrogen or water (which are believed to be abundant in giant planets) that is imploded in a multi-layered target by the ion beam. Detailed numerical simulations have shown that using parameters of the heavy ion beam that will be available at FAIR, one can generate physical conditions that have been predicted to exist in the interior of giant planets. In the present paper, we report simulations of compression of water that show that one can generate a plasma phase as well as a superionic phase of water in the LAPLAS experiments. [ABSTRACT FROM AUTHOR]

Abstract: The paper summarises damage tolerance investigations on railway rails which the authors have carried out in the context of the German–French joint project NOVUM (novel methods for quantitative prediction of rail performance at increased service loads) [Girardi L, Heyder R, Dider L, Boulanger D. IDR2-NOVUM promises lower rail maintenance costs. Railway Gazette Int 2005;(July):439–41]. The investigations include the determination of the crack driving force as a function of the various loading components a rail is subjected to and the simulation of residual lifetime. Features such as the local load input at the rail–wheel interface, dynamic effects and statistical aspects of crack resistance are explicitly taken into account. [Copyright &y& Elsevier]

Analyses of spatial distributions in ecology are often influenced by spatial autocorrelation. While methods to deal with spatial autocorrelation in Normally distributed data are already frequently used, the analysis of non-Normal data in the presence of spatial autocorrelation are rarely known to ecologists. Several methods based on the generalized estimating equations (GEE) are compared in their performance to a better known autoregressive method, namely spatially simultaneous autoregressive error model (SSAEM). GEE are further used to analyze the influence of autocorrelation of observations on logistic regression models. Originally, these methods were developed for longitudinal data and repeated measures models. This paper proposes some techniques for application to two-dimensional macroecological and biogeographical data sets displaying spatial autocorrelation. Results are presented for both computationally simulated data and ecological data (distribution of plant species richness throughout Germany and distribution of the plant species Hydrocotyle vulgaris). While for Normally distributed data SSAEM perform better than GEE, GEE provide far better results than frequently used autologistic regressions and remove residual spatial autocorrelation substantially when having binary data. [Copyright &y& Elsevier]

When a lightning strikes a high object, the current flows along the object and produces in this way a field component additional to the field radiated from the lightning channel. This additional field component enhances the field compared to lightning to flat ground. In this article, the field enhancement is analyzed for lightning striking the Peissenberg Tower, Germany. The analysis is based on investigations of the far field at distances from 10 to 1000 km. In the computer simulations, the return stroke process is taken into account with the transmission line (TL)-model and the tower is modelled with the computer program CONCEPT II based on the method of moments. In a first step, the pure effect of the tower is analyzed. In this case, the ground is taken into account as perfectly conducting plane. In the next step, the effect of the field propagation is added by introducing an attenuation function based on the solution of Sommerfeld and a far-field approximation of Norton. For fast rising return stroke currents and relatively near distances between 10 and 30 km, the field enhancement may exceed 100%. The field enhancement decreases strongly with decreasing soil conductivity (σ) and increasing distance (s), while the influence of the permittivity (ϵ) is rather small. At a distance of more than 100 km the field enhancement is typically in the range of some tens of percent. This result agrees well with the data of the European lightning location system EUCLID. From EUCLID an average field enhancement of about 20% is reported for lightning striking the Peissenberg Tower. [ABSTRACT FROM AUTHOR]

Background: A standard parameter to compare the disease incidence of a cohort relative to the population is the standardized incidence ratio (SIR). For statistical inference is commonly assumed that the denominator, the expected number of cases, is fixed. If a disease registry is available, incident cases can sometimes be identified by linkage with the registry, however, registries may not contain information on migration or death from other causes. A complete follow-up with a population registry may not be possible. In that case, end-of-follow-up date and therefore, exact person-years of observation are unknown.Methods: We have developed a method to estimate the observation times and to derive the expected number of cases using population data on mortality and migration rates. We investigate the impact of the underlying assumptions with a sensitivity analysis.Results: The method provides a useful estimate of the SIR. We illustrate the method with a numerical example, a simulation study and with a study on standardized cancer incidence ratios in a cohort of migrants relative to the German population. We show that the additional variance induced by the estimation method is small, so that standard methods for inference can be applied.Conclusions: Estimation of the observation time is possible for cohort studies with incomplete follow-up. [ABSTRACT FROM AUTHOR]

We present a performance assessment of the European Integrated Carbon Observing System (ICOS) atmospheric network for constraining European biogenic CO2 fluxes (hereafter net ecosystem exchange, NEE). The performance of the network is assessed in terms of uncertainty in the fluxes, using a state-of-the-art mesoscale variational atmospheric inversion system assimilating hourly averages of atmospheric data to solve for NEE at 6 h and 0.5° resolution. The performance of the ICOS atmospheric network is also assessed in terms of uncertainty reduction compared to typical uncertainties in the flux estimates from ecosystem models, which are used as prior information by the inversion. The uncertainty in inverted fluxes is computed for two typical periods representative of northern summer and winter conditions in July and in December 2007, respectively. These computations are based on a observing system simulation experiment (OSSE) framework. We analyzed the uncertainty in a 2-week-mean NEE as a function of the spatial scale with a focus on the model native grid scale (0.5°), the country scale and the European scale (including western Russia and Turkey). Several network configurations, going from 23 to 66 sites, and different configurations of the prior uncertainties and atmospheric model transport errors are tested in order to assess and compare the improvements that can be expected in the future from the extension of the network, from improved prior information or transport models. Assimilating data from 23 sites (a network comparable to presentday capability) with errors estimated from the present prior information and transport models, the uncertainty reduction on a 2-week-mean NEE should range between 20 and 50% for 0.5° resolution grid cells in the best sampled area encompassing eastern France and western Germany. At the European scale, the prior uncertainty in a 2-week-mean NEE is reduced by 50% (66%), down to ~43 TgC month-1 (26 TgC month-1) in July (December). Using a larger network of 66 stations, the prior uncertainty of NEE is reduced by the inversion by 64% (down to ~33 TgC month-1) in July and by 79%(down to ~15 TgC month-1) in December. When the results are integrated over the well-observed western European domain, the uncertainty reduction shows no seasonal variability. The effect of decreasing the correlation length of the prior uncertainty, or of reducing the transport model errors compared to their present configuration (when conducting real-data inversion cases) can be larger than that of the extension of the measurement network in areas where the 23 station observation network is the densest. We show that with a configuration of the ICOS atmospheric network containing 66 sites that can be expected on the long-term, the uncertainties in a 2-week-mean NEE will be reduced by up to 50-80% for countries like Finland, Germany, France and Spain, which could significantly improvement (and at least a high complementarity to) our knowledge of NEE derived from biomass and soil carbon inventories at multi-annual scales. [ABSTRACT FROM AUTHOR]

The spatial structure and the progression speed of the first ash layer from the Icelandic Eyjafjallajökull volcano which reached Germany on 16/17 April is investigated from remote sensing data and numerical simulations. The ceilometer network of the German Meteorological Service was able to follow the progression of the ash layer over the whole of Germany. This first ash layer turned out to be a rather shallow layer of only several hundreds of metres thickness which was oriented slantwise in the middle troposphere and which was brought downward by large-scale sinking motion over Southern Germany and the Alps. Special Raman lidar measurements, trajectory analyses and in-situ observations from mountain observatories helped to confirm the volcanic origin of the detected aerosol layer. Ultralight air-craft measurements permitted the detection of the arrival of a second major flush of volcanic material in Southern Germany. Numerical simulations with the Eulerian meso-scale model MCCM were able to reproduce the temporal and spatial structure of the ash layer. Comparisons of the model results with the ceilometer network data on 17 April and with the ultralight aircraft data on 19 April were satisfying. This is the first example of a model validation study from this ceilometer network data. [ABSTRACT FROM AUTHOR]