Terahertz dynamic aperture imaging at stand-off distances using a Compressed Sensing protocol

In this text, results of a 0.35 terahertz (THz) dynamic aperture imaging approach are presented. The experiments use an optical modulation approach and a single pixel detector at a stand-off imaging distance of approx 1 meter. The optical modulation creates dynamic apertures of 5cm diameter with approx 2000 individually controllable elements. An optical modulation approach is used here for the first time at a large far-field distance, for the investigation of various test targets in a field-of-view of 8 x 8 cm. The results highlight the versatility of this modulation technique and show that this imaging paradigm is applicable even at large far-field distances. It proves the feasibility of this imaging approach for potential applications like stand-off security imaging or far field THz microscopy.Comment: 9 pages, 13 figure

Modelling material mass balances over wastewater treatment plants

Includes bibliographical references.The overall objective of whole wastewater treatment plant (WWTP)modelling is to develop a COD (electron), carbon (C), nitrogen (N), phosphorus (P), alkilinity (proton), calcium (Ca), magnesium (Mg) and inorganic suspended solids (ISS) concentrations mass balances models for unit operations in municipal WWTPs. The development of such a model, for both steady state and dynamic simulation conditions, is an objective greater that this thesis project, however, it makes a number of significant steps towards it

Teaching in the Montessori Classroom: Investigating Variation Theory and Embodiment as a Foundation of Teachers’ Development

The theory of Montessori education has been interpreted by some researchers to be vaguely formulated. However, as shown in previous research, Maria Montessori’s didactic approach to teaching and learning mathematics is fully consistent with variation theory and the theory of embodiment. Dr. Montessori used the theoretical concept of isolation of quality, which means that the learning objects have to be kept identical except for one variable, which has to differ to be perceptible. This concept is in alignment with variation theory, which emphasizes variation as a necessary condition for learners to discern aspects of an object of learning. The other theory applied in this article is the theory of embodiment: important cognitive functions are fundamentally grounded in action that is concordant with Dr. Montessori’s view that mind and movement are parts of the same entity.                 This article reports on a qualitative single-case study with a formative intention in which we investigated the significance of being acquainted with variation theory and the theory of embodiment when working with Montessori material. The study analyzes a teacher’s mathematics presentations with the Montessori material and the children’s work with this material, using Epistemological Move Analysis, which focuses on how the teacher directs children’s learning. The analysis was shared with the teacher to support her awareness of the ways teaching can be developed from a variation and embodiment theoretical perspective. Results show that the teacher’s awareness of why a specific learning object be treated in accordance with variation theory and embodiment seems to promote a more constructive and effective way to direct children’s learning

Long-term measurements of mesospheric and lower thermospheric winds using specular meteor radars

Long-term measurements of winds in the mesosphere and lower thermosphere are of fundamental importance to detect global circulation patterns and their effects on the entire atmosphere. Measurements of winds and atmospheric waves seem to depend on the used instrument and the applied method to infer a decompose of the observed time series. Furthermore, differences in the measurements occur due to the observed location, the season, and the altitude range. Aim of this thesis is a study of horizontal winds and their oscillations at the middle and polar latitudes, in view of their long-term change.Langzeitmessungen von Winden in der Mesosphäre und unteren Thermosphäre sind von grundlegender Bedeutung, um globale Zirkulationsmuster und ihre Auswirkungen auf die gesamte Atmosphäre zu erfassen. Diese Messungen variieren je nach verwendetem Instrument und der angewandten Methode zur Zerlegung der beobachteten Zeitreihen. Darüber hinaus treten Unterschiede je nach Beobachtungsort, Jahreszeit und Höhenbereich auf. Ziel dieser Arbeit ist die Untersuchung horizontaler Winde und ihrer Schwingungen in mittleren und polaren Breiten im Hinblick auf ihre langfristige Veränderung

Climatologies and long-term changes in mesospheric wind and wave measurements based on radar observations at high and mid latitudes

We report on long-term observations of atmospheric parameters in the mesosphere and lower thermosphere (MLT) made over the last 2 decades. Within this study, we show, based on meteor wind measurement, the long-term variability of winds, tides, and kinetic energy of planetary and gravity waves. These measurements were done between the years 2002 and 2018 for the high-latitude location of Andenes (69.3°N, 16°E) and the mid-latitude locations of Juliusruh (54.6°N, 13.4°E) and Tavistock (43.3°N, 80.8°W). While the climatologies for each location show a similar pattern, the locations differ strongly with respect to the altitude and season of several parameters. Our results show annual wind tendencies for Andenes which are toward the south and to the west, with changes of up to 3°m s-1 per decade, while the mid-latitude locations show smaller opposite tendencies to negligible changes. The diurnal tides show nearly no significant long-term changes, while changes for the semidiurnal tides differ regarding altitude. Andenes shows only during winter a tidal weakening above 90°km, while for the Canadian Meteor Orbit Radar (CMOR) an enhancement of the semidiurnal tides during the winter and a weakening during fall occur. Furthermore, the kinetic energy for planetary waves showed strong peak values during winters which also featured the occurrence of sudden stratospheric warming. The influence of the 11-year solar cycle on the winds and tides is presented. The amplitudes of the mean winds exhibit a significant amplitude response for the zonal component below 82°km during summer and from November to December between 84 and 95°km at Andenes and CMOR. The semidiurnal tides (SDTs) show a clear 11-year response at all locations, from October to November. © 2019 by ASME

Are byline biases an issue of the past? The effect of author’s gender and emotion norm prescriptions on the evaluation of news articles on gender equality

When female journalists write about issues of gender equality, they often become the target of incivility and their work is devaluated. Research has investigated such devaluations based on journalists’ gender under the scope of byline biases, analysing if it matters to readers whether a news piece is authored by a male or female journalist. In this paper, we set out to study if gender byline biases occur when journalists write about gender equality. As gender attributions become particularly salient through the presentation of gendered emotion norms, we also inquire in how it matters for readers’ interest in reading such an article and the attributed credibility of the author when an article prescribes gender-specific emotions. We report findings from two consecutive experimental studies, manipulating gender bylines and emotion norm prescriptions and include reader gender as a quasi-experimental factor. Our findings show that gender byline biases against female authors are depending on content and context characteristics and only become activated when gender cues are clearly visible. At the same time, we found a tendency to judge female authors as more credible for topics on gender equality, which (partly) mitigated negative effects on reading intention for female authors. The prescription of emotion norms did not further strengthen biases against female authors. Our study opens the path for further investigations into the question when gender bylines are activated and underlines the challenges for female journalists’ visibility when they address controversial issues such as gender equality

A comparison of 11-year mesospheric and lower thermospheric winds determined by meteor and MF radar at 69 ° N

The Andenes Meteor Radar (MR) and the Saura Medium Frequency (MF) Radar are located in northern Norway (69° N, 16° E) and operate continuously to provide wind measurements of the mesosphere and lower thermosphere (MLT) region. We compare the two systems to find potential biases between the radars and combine the data from both systems to enhance altitudinal coverage between 60 and 110 km. The systems have altitudinal overlap between 78 and 100 km at which we compare winds and tides on the basis of hourly winds with 2 km altitude bins. Our results indicate reasonable agreement for the zonal and meridional wind components between 78 and 92 km. An exception to this is the altitude range below 84 km during the summer, at which the correlation decreases. We also compare semidiurnal and diurnal tides according to their amplitudes and phases with good agreement below 90 km for the diurnal and below 96 km for the semidiurnal tides. Based on these findings we have taken the MR data as a reference. By comparing the MF and MR winds within the overlapping region, we have empirically estimated correction factors to be applied to the MF winds. Existing gaps in that data set will be filled with weighted MF data. This weighting is done due to underestimated wind values of the MF compared to the MR, and the resulting correction factors fit to a polynomial function of second degree within the overlapping area. We are therefore able to construct a consistent and homogenous wind from approximately 60 to 110 km

Small-scale structure and dynamics of the lower solar atmosphere

The chromosphere of the quiet Sun is a highly intermittent and dynamic phenomenon. Three-dimensional radiation (magneto-)hydrodynamic simulations exhibit a mesh-like pattern of hot shock fronts and cool expanding post-shock regions in the sub-canopy part of the inter-network. This domain might be called "fluctosphere". The pattern is produced by propagating shock waves, which are excited at the top of the convection zone and in the photospheric overshoot layer. New high-resolution observations reveal a ubiquitous small-scale pattern of bright structures and dark regions in-between. Although it qualitatively resembles the picture seen in models, more observations - e.g. with the future ALMA - are needed for thorough comparisons with present and future models. Quantitative comparisons demand for synthetic intensity maps and spectra for the three-dimensional (magneto-)hydrodynamic simulations. The necessary radiative transfer calculations, which have to take into account deviations from local thermodynamic equilibrium, are computationally very involved so that no reliable results have been produced so far. Until this task becomes feasible, we have to rely on careful qualitative comparisons of simulations and observations. Here we discuss what effects have to be considered for such a comparison. Nevertheless we are now on the verge of assembling a comprehensive picture of the solar chromosphere in inter-network regions as dynamic interplay of shock waves and structuring and guiding magnetic fields.Comment: 8 pages, 2 figures, to appear in the proceedings of the IAU Symposium No. 247, Waves & Oscillations in the Solar Atmosphere: Heating and Magneto-Seismology (Venezuela 2007