Concave holographic grating for spectrographic applications: Study of the aberrations

An analysis of reflecting diffraction gratings by the application of holographic techniques is presented. The subjects discussed are: (1) holographic grating properties, (2) calculation of aberrant optical path, (3) analytical expression of stigmatic points, (4) spherical aberration and limitation of grating width, and (5) determination of construction parameters

Macroeconomic News 'Surprises' and the Rand/Dollar Exchange Rate

Economic theory in the context of floating exchange rates has focussed on underlying medium and long term direction of exchange rate movements. Daily volatility is less well understood. One theory that offers an explanation for short term exchange rate movements is that of the efficient market hypothesis or EMH. Its application to the forex market allows exchange rate movements to be understood as the reaction of traders to relevant news. In an efficient market traders react to news and specifically to surprise news events which necessitate a re-evaluation of the currency value. We test for the validity of this hypothesis in the context of the daily rand/dollar forex market over a three year period, adding an emerging market case to the literature. We test the significance of macroeconomic news surprises -measured by the difference between actual and forecast data - in driving daily exchange rates. We find that surprises in both real and nominal variables cause a statistically significant reaction in the exchange rate. The results support an asymmetry between news of different origin as only surprises that originate in the U.S. prove significant. Good news also seems to receive greater attention from traders than bad news in our sample. Finally, we find that the statistical significance of variables is time-varying.

Interregional transfers, group loyalty and the decentralization of redistribution

We study the decentralization of redistributive taxation in a political economy model assuming regional heterogeneity regarding both group identity and average income. If a centralized system permits a beneficial pooling of national resources, it might also decrease the degree of solidarity in the society. With no group loyalty, centralization Pareto-dominates decentralization even when regions are not identical. Furthermore, increased heterogeneity need not increase the relative efficiency of decentralization. If regions are equally rich, centralization Pareto-dominates decentralization whenever group loyalty is not perfect. Finally, centralization is always more efficient than decentralization even when allowing for interregional transfers

A Letter to My Imperfect Self

I want you to know how much you’ve helped me since I’ve left. You’ve taught me values which I have learned to appreciate more

The Menstrual Cup Effect

This research is dedicated to comparative environmental impact analyses of menstrual products – tampons with and without applicator, sanitary pads, and menstrual cups – used in modern “Western” societies and using six indicators of environmental impact. Additionally, a menstrual waste scenario analysis, with increasing menstrual cup use as variable, is performed. Due to environmental concern, especially for waste, the research question and the survey were formed. All indicators showed lowest impact with menstrual cups. Besides, if menstrual cup-use sextupled, a waste reduction of 84% was calculated. Consumers and researchers must identify and adjust environmental impacts of everyday products, like menstrual products

A 64mW DNN-based Visual Navigation Engine for Autonomous Nano-Drones

Fully-autonomous miniaturized robots (e.g., drones), with artificial intelligence (AI) based visual navigation capabilities are extremely challenging drivers of Internet-of-Things edge intelligence capabilities. Visual navigation based on AI approaches, such as deep neural networks (DNNs) are becoming pervasive for standard-size drones, but are considered out of reach for nanodrones with size of a few cm${}^\mathrm{2}$. In this work, we present the first (to the best of our knowledge) demonstration of a navigation engine for autonomous nano-drones capable of closed-loop end-to-end DNN-based visual navigation. To achieve this goal we developed a complete methodology for parallel execution of complex DNNs directly on-bard of resource-constrained milliwatt-scale nodes. Our system is based on GAP8, a novel parallel ultra-low-power computing platform, and a 27 g commercial, open-source CrazyFlie 2.0 nano-quadrotor. As part of our general methodology we discuss the software mapping techniques that enable the state-of-the-art deep convolutional neural network presented in [1] to be fully executed on-board within a strict 6 fps real-time constraint with no compromise in terms of flight results, while all processing is done with only 64 mW on average. Our navigation engine is flexible and can be used to span a wide performance range: at its peak performance corner it achieves 18 fps while still consuming on average just 3.5% of the power envelope of the deployed nano-aircraft.Comment: 15 pages, 13 figures, 5 tables, 2 listings, accepted for publication in the IEEE Internet of Things Journal (IEEE IOTJ

Macroeconomic News ‘Surprises’ and the Rand/Dollar Exchange Rate

Economic theory in the context of floating exchange rates has focussed on underlying medium and long term direction of exchange rate movements. Daily volatility is less well understood. One theory that offers an explanation for short term exchange rate movements is that of the efficient market hypothesis or EMH. Its application to the forex market allows exchange rate movements to be understood as the reaction of traders to relevant news. In an efficient market traders react to news and specifically to surprise news events which necessitate a re-evaluation of the currency value. We test for the validity of this hypothesis in the context of the daily rand/dollar forex market over a three year period, adding an emerging market case to the literature. We test the significance of macroeconomic news surprises -measured by the difference between actual and forecast data - in driving daily exchange rates. We find that surprises in both real and nominal variables cause a statistically significant reaction in the exchange rate. The results support an asymmetry between news of different origin as only surprises that originate in the U.S. prove signifi- cant. Good news also seems to receive greater attention from traders than bad news in our sample. Finally, we find that the statistical significance of variables is time-varying