Regression Based Expected Shortfall Backtesting

This paper introduces novel backtests for the risk measure Expected Shortfall (ES) following the testing idea of Mincer and Zarnowitz (1969). Estimating a regression framework for the ES stand-alone is infeasible, and thus, our tests are based on a joint regression for the Value at Risk and the ES, which allows for different test specifications. These ES backtests are the first which solely backtest the ES in the sense that they only require ES forecasts as input parameters. As the tests are potentially subject to model misspecification, we provide asymptotic theory under misspecification for the underlying joint regression. We find that employing a misspecification robust covariance estimator substantially improves the tests' performance. We compare our backtests to existing approaches and find that our tests outperform the competitors throughout all considered simulations. In an empirical illustration, we apply our backtests to ES forecasts for 200 stocks of the S&P 500 index

Wolf 1465: Not a Bright Dwarf Carbon Star

Wolf 1465 has been suggested as a candidate for a bright dwarf carbon star. It is not

Harmonic correction in power supplies feeding non-linear loads

This paper focuses on the design of an electronic circuit which can be used in conjunction with the power supplies used at the input of non-linear loads (computers, TV sets, etc.) in order to filter out the input current harmonics in such loads. The electronic circuit will fill the gaps of the distorted current waveform so that it becomes sinusoidal and also in phase with the mains supply. In this paper different configurations of the proposed electronic circuit are covered (depending on the location with respect to the non-linear load). An optimization algorithm is carried out in order to find the best location, minimum device rating for different type of loads. The proposed circuit monitors the input current, output voltage and power rating of the power supply. The circuit will then decide whether to filter the input current harmonics or the output voltage harmonics. The circuit will also optimize the best switching frequency for the required load so that the power supply operates at the maximum possible efficiency

Early X-ray emission from Type Ia supernovae originating from symbiotic progenitors or recurrent novae

One of the key observables for determining the progenitor nature of Type Ia supernovae is provided by their immediate circumstellar medium, which according to several models should be shaped by the progenitor binary system. So far, X-ray and radio observations indicate that the surroundings are very tenuous, producing severe upper-limits on the mass loss from winds of the progenitors. In this study, we perform numerical hydro-dynamical simulations of the interaction of the SN ejecta with circumstellar structures formed by possible mass outflows from the progenitor systems and we estimate numerically the expected numerical X-ray luminosity. We consider two kinds of circumstellar structures: a) A circumstellar medium formed by the donor star's stellar wind, in case of a symbiotic binary progenitor system; b) A circumstellar medium shaped by the interaction of the slow wind of the donor star with consecutive nova outbursts for the case of a symbiotic recurrent nova progenitor system. For the hydro-simulations we used well-known Type Ia supernova explosion models, as well as an approximation based on a power law model for the density structure of the outer ejecta. We confirm the strict upper limits on stellar wind mass loss, provided by simplified interpretations of X-ray upper limits of Type Ia supernovae. However, we show that supernova explosions going off in the cavities created by repeated nova explosions, provide a possible explanation for the lack of X-ray emission from supernovae originating from symbiotic binaries. Moreover, the velocity structure of circumstellar medium, shaped by a series of nova explosion matches well with the Na absorption features seen in absorption toward several Type Ia supernovae.Comment: 11 pages, 12 figures, submitted to MNRA

NEW shared & interconnected ASL resources: SignStream® 3 Software; DAI 2 for web access to linguistically annotated video corpora; and a sign bank

2017 marked the release of a new version of SignStream® software, designed to facilitate linguistic analysis of ASL video. SignStream® provides an intuitive interface for labeling and time-aligning manual and non-manual components of the signing. Version 3 has many new features. For example, it enables representation of morpho-phonological information, including display of handshapes. An expanding ASL video corpus, annotated through use of SignStream®, is shared publicly on the Web. This corpus (video plus annotations) is Web-accessible—browsable, searchable, and downloadable—thanks to a new, improved version of our Data Access Interface: DAI 2. DAI 2 also offers Web access to a brand new Sign Bank, containing about 10,000 examples of about 3,000 distinct signs, as produced by up to 9 different ASL signers. This Sign Bank is also directly accessible from within SignStream®, thereby boosting the efficiency and consistency of annotation; new items can also be added to the Sign Bank. Soon to be integrated into SignStream® 3 and DAI 2 are visualizations of computer-generated analyses of the video: graphical display of eyebrow height, eye aperture, an

The use of information systems for logistics and supply chain management in South East Europe: Current status and future direction

This research aims to investigate the current status and future direction of the use of information systems for logistics and supply chain management (LSCM) in South East Europe. The objectives are threefold: (1) to identify major challenges and developments on the use of information systems for LSCM by enterprises, (2) to examine the actual level of satisfaction of current policy on LSCM, and (3) to reveal the actual need of enterprises in South East Europe on effective use of information systems for LSCM. Mixed methodology of literature review and questionnaire survey is adopted in this research. Data collected from 79 enterprises are analysed using descriptive analysis in SPSS. The findings suggest that enterprises in Albania, Bulgaria, Greece, Former Yugoslav Republic of Macedonia (FYROM), Romania, and Serbia and Montenegro, face similar challenges but all are in different stages of developments of LSCM. Their use of information systems explains their heavy focus on supply chain partnership and weakness in demand chain partnership. Major findings suggest that companies and governments alike in that region do not seem to be ready for playing a significant and demanding role in global supply chains. Current deficiencies, including limited abilities in building valuable forward relations, weak strategic planning and organisation, and infrastructural problems, are major obstacles for fast development in LSCM. At the same time though, traces of changing mentalities do exist, setting the ground for improved performance and ultimately for a better position in global business