Money makes the world go round ... about the necessity of nonlinear techniques in interest rate forecasting

One of the key variables for a bank's management is the development of the "risk-free interest rate", which is the reference for all bond and loan rates as well as an indicator for the state of the economy and therefore the bank"s future perspectives. Turning towards long-term analysis, the risk-free rate is usually supposed to be the return of a superior-rated government bond (in most cases the return of the German 10-year Government Bond). Due to the importance of this risk-free rate, nearly all large economic and financial institutions deal with the analysis of its future development. In this paper we try to find out whether modelling non-linear relationships between variables can enhance forecast ability. We apply multi-layer perceptrons (MLP) as non-linear modelling tool beside an error correction model and a basic structural model with ARMA terms. Using seasonally unadjusted monthly data from 1960-2003, we forecast the interest rate for a two year hold-out sample. The obtained results give evidence of the underlying non-linearity of the problem. The MLP outperform the classical tools with regard to different error measures.Neural Networks, Interest Rate Forecasting

Legal and illegal cartels in the European cement industry

Due to being much better documented, legal cartels have recently attracted the interest of many researchers who aim to understand the functioning of illegal cartels in detail. This paper contributes to the question of what we can learn from legal cartels by taking a closer look at the cement industry which has a rich history of both legal and illegal cartels. We undertake a cross-country comparison for Austria, Germany, Poland and Norway, providing narrative evidence for many traits of the cases based on a variety of detailed sources. We identify similarities between legal and illegal cartels in aspects such as monitoring efforts, information exchange, the importance of industry associations and the role of capacities, whereas we also find substantial differences in the allocation of clients, reactions to deviations and pricing schedules

15 min DC breakdown tests with pressurized liquid nitrogen

Liquid nitrogen is a widely applied cooling fluid for superconducting high voltage devices. The pressure dependence of the dielectric strength of liquid nitrogen is an important design issue in case of using liquid nitrogen for high voltage insulation purposes, too. The objective of the FASTGRID project is to support a liquid nitrogen cooled superconducting fault current limiter solution for DC grids. Occurrence of heat impulses, caused by transition from the superconducting to the normal conductive state, is an unavoidable feature of a superconducting fault current limiter and therefore the influence of such heat impulses were also investigated. The high voltage test facility Fatelini 2 allows DC testing of liquid nitrogen up to voltages of 325 kV and pressures up to 3 bar (absolute). A high voltage electrode with the shape similar to a bell and a ground plane electrode with an internal resistive heater were used. The pressurization causes subcooled conditions leading to a negligible sensitivity of the breakdown strength against heating which is different from the heat sensitive breakdown behaviour for the non-subcooled condition. The polarity effect changed after subcooling in case of testing the long gap setups. Calculated maximum field values based on the experimental withstand voltages for gap lengths between 10 mm and 96 mm are above 6.0 kV / mm

Burden of Covid-19 restrictions: National, regional and global estimates

Background: A growing literature has documented the high global morbidity, mortality and mental health burden associated with the current Covid-19 pandemic. In this paper, we aimed to quantify the total utility and quality of life loss resulting from Covid-19-related government restrictions imposed at the national, regional and global levels. Methods : We conducted quality of life online surveys in France, India, Italy, UK and the United States of America between June 21st and September 13th 2021, and used regression models to estimate the average quality of life loss due to light and severe restrictions in these countries. We then combined estimated disutility weights from the pooled sample with the latest data on Covid-19 restrictions exposure in each country to estimate the total disutility generated by restrictions at the national, regional and global level. We also embedded a discrete choice experiment (DCE) into the online survey to estimate average willingness to pay to avoid specific restrictions. Findings : A total of 947 surveys were completed. Thirty-five percent of respondents were female, and 69.5% were between 18 and 39 years old. The weighted average utility weight was 0.71 (95% CIs 0.69−0.74) for light restrictions, and 0.65 (0.63−0.68) for severe restrictions. At the global scale, this implies a total loss of 3259 million QALYs (95% 3021, 3496) as of September 6th, 2021, with the highest burden in lower and upper middle-income countries. Utility losses appear to be particularly large for closures of schools and daycares as well as restaurants and bars, and seem relatively small for wearing masks and travel restrictions. Interpretation: The results presented here suggest that the QALY losses due to restrictions are substantial. Future mitigation strategies should try to balance potential reductions in disease transmission achievable through specific measures against their respective impact on quality of life. Additional research is needed to determine differences in restriction-specific disutilities across countries, and to determine optimal policy responses to similar future disease threats

Establishing construct validity of a virtual-reality training simulator for hysteroscopy via a multimetric scoring system

Background: The aims of this study are to determine construct validity for the HystSim virtual-reality (VR) training simulator for hysteroscopy via a new multimetric scoring system (MMSS) and to explore learning curves for both novices and experienced surgeons. Methods: Fifteen relevant metrics had been identified for diagnostic hysteroscopy by means of hierarchical task decomposition. They were grouped into four modules (visualization, ergonomics, safety, and fluid handling) and individually weighted, building the MMSS for this study. In a first step, 24 novice medical students and 12 experienced gynecologists went through a self-paced teaching tutorial, in which all participants received clearly stated goals and instructions on how to carry out hysteroscopic procedures properly for this study. All subjects performed five repeated trials on two different exercises on HystSim (exploration and diagnosis exercises). After each trial the results were presented to the participants in the form of an automated objective feedback report (AOFR). Construct validity for the MMSS and learning curves were investigated by comparing the performance between novices and experienced surgeons and in between the repeated trials. To study the effect of repeated practice, 23 of the novices returned 2weeks later for a second training session. Results: Comparing novices with the experienced group, the ergonomics and fluid handling modules resulted in construct validity, while the visualization module did not, and for the safety module the experienced group even scored significantly lower than novices in both exercises. The overall score showed only construct validity when the safety module was excluded. Concerning learning curves, all subjects improved significantly during the training on HystSim, with clear indication that the second training session was beneficial for novice surgeons. Conclusions: Construct validity for HystSim has been established for different modules of VR metrics on a new MMSS developed for diagnostic hysteroscopy. Careful refinement and further testing of metrics and scores is required before using them as assessment tools for operative skill