Stylised Facts and the Contribution of Simulation to the Economic Analysis of Budgeting

The application of computer simulation as a research method raises two important questions: (1) Does simulation really offer added value over established methods? (2) How can the danger of arbitrariness caused by the extended modelling possibilities be minimised? We present the concept of stylised facts as a methodological basis for approaching these questions systematically. In particular, stylised facts provide a point of reference for a comparative analysis of models intended to explain an observable phenomenon. This is shown with reference to a recent discussion in the "economic analysis of accounting" literature where established methods, i.e. game theory, as well as computer simulations are used: the susceptibility of the "Groves mechanism" to collusion. Initially, we identify six stylised facts on the stability of collusion in empirical studies. These facts serve as a basis for the subsequent comparison of four theoretical models with reference to the above questions: (1) We find that the simulation models of Krapp and Deliano offer added value in comparison to the game theoretical models. They can be related to more stylised facts, achieve a better reproduction and exhibit far greater potential for incorporating yet unaddressed stylised facts. (2) Considered in the light of the stylised facts to which the models can be related, Deliano's simulation model exhibits considerable arbitrariness in model design and lacks information on its robustness. In contrast, Krapp demonstrates that this problem is not inherent to the method. His simulation model methodically extends its game theoretical predecessors, leaving little room for arbitrary model design or questionable parameter calibration. All in all, the stylisedfactsconcept proved to be very useful in dealing with the questions simulation researchers are confronted with. Moreover, a "research landscape" emerges from the derived stylised facts pinpointing issues yet to be addressed.Computer Simulation, Stylised Facts, Methodology, Groves Mechanism, Collusion, Game Theory

Floating architecture and structures – an answer to the global changes

Currently a contradictory global situation takes place. The climate and social changes are progressing. The sea level is rising by the smelting of ice and the extension of ocean owing to the temperature rise. This means: the building ground reduces above all things in costal and river districts. On the other hand the mankind and its claims with regard to living room is growing and more building sites are necessary. A smart solution for the conflict situation is the floating architecture. This means floating settlements and cities. In the consideration should be taken also so-called amphibious and floatable houses as a solution in case of floods in river destrics. Technical and social questions must be investigated. Some examples for the problems are demonstrated in the paper

Determining the Pore Size Distribution in Synthetic and Building Materials Using 1D NMR

NMR is gaining increasing interest in civil engineering for applications regarding microstructure characterization as e.g., to determine pore sizes or to monitor moisture transport in porous materials. This study reveals the capability of NMR as a tool for pore size characterization. Therefore, we measured floor screed and synthetic materials at partial and full saturation. For most examined materials, the pore size distribution was successfully determined using either a reference or a calibration method. Since diffusion effects were observed for some samples in single-sided NMR measurements, further tests employing an NMR core analyzer were carried out in a homogeneous magnetic field. The finally obtained surface relaxivity of floor screed (50 μm/s) resulted to be much higher than suggested by literature

Magnetization of Charge-ordered la(2-x)sr(x)nio(4+delta)

We report magnetization measurements on La(2-x)Sr(x)NiO(4+ delta) single crystals, with 0 < x < 0.5. Glassy behaviour associated with the formation of spin-charge stripes, and a separate spin-glass phase at low temperatures were observed. We have also found a `memory effect' in the magnetic field -- temperature history, which is found to be suppressed in the low temperature spin state of the x = 0.33 crystal.Comment: 2 pages, 2 figures. Presented at ICM2003 to appear in J. Magn. Magn. Mat

Airfoil in a high amplitude oscillating stream

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A combined theoretical and experimental investigation was carried out with the objective of evaluating theoretical predictions relating to a two-dimensional airfoil subjected to high amplitude harmonic oscillation of the free stream at constant angle of attack. Current theoretical approaches were reviewed and extended for the purposes of quantifying the bound, unsteady vortex sheet strength along the airfoil chord. This resulted in a closed form solution that is valid for arbitrary reduced frequencies and amplitudes. In the experiments, the bound, unsteady vortex strength of a symmetric 18 % thick airfoil at low angles of attack was measured in a dedicated unsteady wind tunnel at maximum reduced frequencies of 0.1 and at velocity oscillations less than or equal to 50 %. With the boundary layer tripped near the leading edge and mid-chord, the phase and amplitude variations of the lift coefficient corresponded reasonably well with the theory. Near the maximum lift coefficient overshoot, the data exhibited an additional high-frequency oscillation. Comparisons of the measured and predicted vortex sheet indicated the existence of a recirculation bubble upstream of the trailing edge which sheds into the wake and modifies the Kutta condition. Without boundary layer tripping, a mid-chord bubble is present that strengthens during flow deceleration and its shedding produces a dramatically different effect. Instead of a lift coefficient overshoot, as per the theory, the data exhibit a significant undershoot. This undershoot is also accompanied by high-frequency oscillations that are characterized by the bubble shedding. In summary, the location of bubble and its subsequent shedding play decisive roles in the resulting temporal aerodynamic loads

Body mass index distribution in rheumatoid arthritis: a collaborative analysis from three large German rheumatoid arthritis databases

Background METARTHROS (Metabolic impact on joint and bone disease) is a nationwide German network to investigate the overlap between inflammatory and metabolic diseases. The objective of this study was to compare the body mass index (BMI) distribution in patients with early and established rheumatoid arthritis (RA) with data from the general population, and to evaluate the association of BMI with patient characteristics and clinical markers. Methods The BMI distribution was examined with data collected at inclusion of patients in the early arthritis cohort CAPEA, the biologics register RABBIT, and the National database of the German Collaborative Arthritis Centers. A data source with a representative sample of the German population (German Ageing Survey) was used as a comparator. BMI categories of <18.5 kg/m2 (underweight), 18.5 to <25 kg/m2 (normal weight), 25 to <30 kg/m2 (overweight), and ≥30 kg/m2 (obese) were used. Patients were stratified by age and sex, and compared to controls from the German Ageing Survey. Associations between BMI and markers of disease activity were analysed with non-parametric tests and linear models. Results Data from 1207 (CAPEA), 12,230 (RABBIT), and 3424 (National database) RA patients and 6202 population controls were evaluated. The mean age was 56, 56, 62, and 62 years, respectively, the mean disease duration was 13 weeks, 9.9 years, and 13.5 years, respectively, and the mean disease activity score (DAS28) was 5.1, 5.2, and 3.1, respectively. In all RA cohorts, obesity was more frequent (23.8 %, 23.4 %, 21.4 %, respectively) than in controls (18.2 %). This applied to all age groups <70 years, was independent of disease duration, and was more pronounced in females. In all cohorts, the age at RA onset was associated with BMI, being higher in overweight/obese patients compared to normal-weight patients. Current smoking was negatively associated with BMI. Linear analyses revealed increased erythrocyte sedimentation rate (ESR) values in underweight and obese females, and an increasing disparity between tender joint counts (TJCs) and swollen joint counts (SJCs) in higher BMI categories. Conclusions Compared to the general population, a higher prevalence of obesity was observed in all RA cohorts. The dominance of obesity in females and the different behaviour of disease activity markers in relation to the BMI in females indicate that additional parameters need to be considered when analysing the impact of obesity on inflammation in RA

EULAR COVID-19 registry: lessons learnt and future considerations.

Future disease outbreaks of epidemic proportion are inevitable. Advance planning and preparation is essential to mitigate future public health risks; the WHO emphasises the importance of in-depth evaluation of response to and lessons learnt from a national/international pandemic.1 Research is critical to an informed, evidence-based response, therefore establishing pandemic research study protocols, systems to manage and report data, and rapid response teams are considered key to well-prepared, accelerated research in public health emergencies.2 Establishing international data collection registries poses many challenges, which are only amplified in the urgent nature of a global pandemic. The aim of this manuscript is to reflect on the successes and challenges of the European Alliance of Associations for Rheumatology (EULAR) COVID-19 registry3 to better understand how the rheumatology community (and other disease-specific communities) can be better prepared for rapid response research in the future. In particular, we consider the successes and challenges of the registry, what can be learnt from this experience, and what procedures and resources should be established and strengthened now in preparation for future pandemics

Clinical and functional remission: even though biologics are superior to conventional DMARDs overall success rates remain low – results from RABBIT, the German biologics register

We investigated the frequency of remission according to the disease activity score (DAS28) definition, modified American Rheumatology Association (ARA) criteria, and the frequency of an achievement of a functional status above defined thresholds ('functional remission', 'physical independence') in rheumatoid arthritis (RA) patients treated with either biologics or conventional DMARDs. We used the data of a prospective cohort study, the German biologics register RABBIT (German acronym for Rheumatoid Arthritis – Observation of Biologic Therapy) to investigate the outcomes in RA patients with two or more DMARD failures who received new treatment with biologics (BIOL; n = 818) or a conventional DMARD (n = 265). Logistic regression analysis was applied to adjust for differences in baseline risks. Taking risk indicators such as previous DMARD failures or baseline clinical status into account, we found that biologics doubled the chance of remission compared to conventional DMARD therapies (DAS28 remission, adjusted odds ratio (OR) 1.95 (95% confidenece interval (CI) 1.2–3.2)); ARA remission, OR 2.05 (95% CI 1.2–3.5)). High remission rates (DAS28 remission, 30.6%; ARA remission, 16.9%) were observed in BIOL patients with a moderate disease activity (DAS28, 3.2 to 5.1) at the start of treatment. These rates decreased to 8.5% in patients with DAS28 > 6. Sustained remission at 6 and 12 months was achieved in <10% of the patients. Severely disabled patients (≤50% of full function) receiving biologic therapies were significantly more likely to achieve a status indicating physical independence (≥67% of full function) than controls (OR 3.88 (95% CI 1.7–8.8)). 'Functional remission' (≥83% of full function) was more often achieved in BIOL than in controls (OR 2.18 (95% CI 1.04–4.6)). In conclusion, our study shows that biologics increase the chance to achieve clinical remission and a status of functional remission or at least physical independence. However, temporary or even sustained remission remain ambitious aims, which are achieved in a minority of patients only

Impact of disease activity and treatment of comorbidities on the risk of myocardial infarction in rheumatoid arthritis

Background The aim was to estimate the impact of individual risk factors and treatment with various disease-modifying antirheumatic drugs (DMARDs) on the incidence of myocardial infarction (MI) in patients with rheumatoid arthritis (RA). Methods We analysed data from 11,285 patients with RA, enrolled in the prospective cohort study RABBIT, at the start of biologic (b) or conventional synthetic (cs) DMARDs. A nested case–control study was conducted, defining patients with MI during follow-up as cases. Cases were matched 1:1 to control patients based on age, sex, year of enrolment and five cardiovascular (CV) comorbidities. Generalized linear models were applied (Poisson regression with a random component, conditional logistic regression). Results In total, 112 patients developed an MI during follow-up. At baseline, during the first 6 months of follow-up and prior to the MI, inflammation markers (erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)) but not 28-joint-count disease activity score (DAS28) were significantly higher in MI cases compared to matched controls and the remaining cohort. Baseline treatment with DMARDs was similar across all groups. During follow-up bDMARD treatment was significantly more often discontinued or switched in MI cases. CV comorbidities were significantly less often treated in MI cases vs. matched controls (36 % vs. 17 %, p < 0.01). In the adjusted regression model, we found a strong association between higher CRP and MI (OR for log-transformed CRP at follow-up: 1.47, 95 % CI 1.00; 2.16). Furthermore, treatment with prednisone ≥10 mg/day (OR 1.93, 95 % CI 0.57; 5.85), TNF inhibitors (OR 0.91, 95 % CI 0.40; 2.10) or other bDMARDs (OR 0.85, 95 % CI 0.27; 2.72) was not associated with higher MI risk. Conclusions CRP was associated with risk of MI. Our results underline the importance of tight disease control taking not only global disease activity, but also CRP as an individual marker into account. It seems irrelevant with which class of (biologic or conventional) DMARD effective control of disease activity is achieved. However, in some patients the available treatment options were insufficient or insufficiently used - regarding DMARDs to treat RA as well as regarding the treatment of CV comorbidities