On-scalp MEG using high-Tc SQUIDs: Measuring brain activity with superconducting magnetometers

This thesis describes work done towards realizing on-scalp magnetoencephalography (MEG) based on high critical temperature (high-Tc) superconducting quantum interference device (SQUID) sensors. MEG is a non-invasive neuroimaging modality that records the magnetic fields produced by neural currents with good spatial and high temporal resolution. However, state-of-the-art MEG is limited by the use of liquid helium-cooled sensors (T ~ 4 K). The amount of thermal insulation between the sensors and the subject\u27s head that is required to achieve the extreme temperature difference (~300 K), typically realized in the form of superinsulation foil and ~2 centimeters of vacuum, limits measurable signals. Replacing the sensors with high-Tc SQUIDs can mitigate this problem. High-Tc SQUIDs operate at much higher temperatures (90 K) allowing significant reduction of the stand-off distance (to ~1 mm). They can furthermore be cooled with liquid nitrogen (77 K), a cheaper, more sustainable alternative to the liquid helium used for cooling in conventional MEG systems.The work described in this thesis can be divided into three main areas: (I) simulation work for practical implementations of on-scalp systems, (II) development of a 7-channel high-Tc SQUID-based on-scalp MEG system, and (III) on-scalp MEG recordings.In the first part, spatial information density (SID), a metric to evaluate the performance of simulated MEG sensor arrays, is introduced and - along with total information capacity - used to compare the performance of various simulated full-head on-scalp MEG sensor arrays.\ua0Simulations demonstrate the potential of on-scalp MEG, with all on-scalp systems exhibiting higher information capacity than the state-of-the-art. SID further reveals more homogeneous sampling of the brain with flexible systems. A method for localizing magnetometers in on-scalp MEG systems is introduced and tested in simulations. The method uses small, magnetic dipole-like coils to determine the location and orientation of individual sensors, enabling straightforward co-registration in flexible on-scalp MEG systems. The effects of different uncertainties and errors on the accuracy of the method were quantified.In the second part, design, construction, and performance of a 7-channel on-scalp MEG system is described. The system houses seven densely-packed (2 mm edge-to-edge), head-aligned high-Tc SQUID magnetometers (9.2 mm x 8.6 mm) inside a single, liquid nitrogen-cooled cryostat. With a single filling, the system can be utilized for MEG recordings for >16 h with low noise levels (~0-130 fT). Using synchronized clocks and a direct injection feedback scheme, the system achieves low sensor crosstalk (<0.6%).\ua0In the third part, on-scalp MEG recordings with the 7-channel system as well as its predecessor, a single-channel system, are presented. The recordings are divided into proof-of-principle and benchmarking experiments. The former consist of well-studied, simple paradigms such as auditory evoked activity and visual alpha. Expected signal components were clearly seen in the on-scalp recordings. The benchmarking studies were done to compare and contrast on-scalp with state-of-the-art MEG. To this end, a number of experimental stimulus paradigms were recorded on human subjects with the high-Tc SQUID-based on-scalp systems as well as a state-of-the-art, commercial full-head MEG system. Results include the expected signal gains that are associated with recording on-scalp as well as new details of the neurophysiological signals. Using the previously described on-scalp MEG co-registration method enabled source localization with high agreement to the full-head recording (the distance between dipoles localized with the two systems was 4.2 mm)

Tax incentives for research and development and their use in tax planning

This study provides a comprehensive analysis of various aspects of R&D tax incentives. It explains the economic justification behind the state support of research and development and summarizes its main types. In addition, it gives an overview of the existing R&D tax incentives in Europe and provides a thorough review of the empirical literature on the outcomes of fiscal incentives. Furthermore, the Devereux and Griffith model is used to determine the effective tax burden of multinational firms that reside in countries which implement R&D tax support and countries which do not. The model is developed further following Spengel and Elschner (2010) and Evers et al. (2015) to reflect a potential use of R&D tax incentives by multinational firms for tax planning. The hypothesis developed in the model is tested in an empirical estimation, where we employ the OECD data on international co-operation in patents. According to our main findings, there are at least two reasons why input-oriented R&D tax incentives, such as tax credits and tax super-deductions, constitute a more suitable instrument for fostering research and development than the output-oriented incentives, such as IP Boxes. First, there is robust evidence found in the empirical literature which shows the positive effect introducing input-oriented tax incentives has on a firm’s innovative activity, whereas studies on output-oriented tax incentives are not able to support this argument. Secondly, according to our theoretical and empirical analyses, output-oriented R&D tax incentives may be used by multinationals for tax planning as opposed to their intended use of fostering research and development

Effects of loperamide on the human hypothalamo-pituitary-adrenal axis in vivo and in vitro.

Loperamide, an opiate agonist of high specificity for p-receptors, was recently reported to suppress ACTH and cortisol levels in normal subjects, but not in patients with proven ACTH-dependent Cushing’s disease. However, there is little information on the site of action of loperamide in the hypothalamo-pituitary-adrenal axis of man. We investigated the effect of loperamide on pituitary hormone secretion in uiuo and in vitro. In seven normal subjects, basal ACTH plasma levels were significantly suppressed 3 h after loperamide administration (16 mg, orally) from 5 + 1 to 2 f 0 pmol/L (P < 0.0001). After the combined pituitary stimulation test (100 pg human CRH, 100 rg GnRH, 100 pg GH-releasing hormone, and 200 pg TRH), the ACTH peak (maximum increase at 30 min) was significantly blunted by loperamide from 9 + 1 to 4 of: 1 pmol/L (P < 0.001) and the area under the curve of ACTH from O-120 min was reduced from 35 + 5 to 23 + 4 pmol/L.2 h (P < 0.05). In the insulin-hypoglycemia test (0.15 IU/kg BW), neither the ACTH peak nor the area under the curve of ACTH was affected by loperamide. In six patients with Cushing’s disease and one patient with secondary adrenal insufficency due to hypothalamic failure, neither basal ACTH and cortisol levels nor CRH-stimulated levels were influenced by loperamide. In four cultured human corticotropic adenomas, loperamide was not able to reduce basal and CRH-induced ACTH secretion. In summary, loperamide is able to reduce basal and CRHinduced ACTH and cortisol levels in normal subjects, but not in patients with Cushing’s disease or secondary adrenal failure of hypothalamic origin. Loperamide has no significant effect on insulin-hypoglycemia- induced ACTH and cortisol levels and, therefore, no effect on stress-induced elevation of cortisol levels. Loperamide might act at a suprapituitary site in man in viuo, but, nevertheless, a pituitary site cannot be excluded

Playing and Reflecting Games: The Production of Gamified Learning Artefacts in Teacher Education

At the University, students played and reflected on different games within a digital course conducted by the teaching study program. In one session students chose and played different games. Guided by questions, they discussed and reflected in groups the potential of games for their own future teaching. Their new found experience was critical for the production of a gamified learning artefact in moodle. The self-evaluation showed that the participants were able to utilize their new set of skills and develop, implement and improve a learning artefact over a self-chosen topic. The following paper describes the didactical approach. We share the results of the students perspectives and learning outcomes towards game based dialogue. Students consider gamification and games as useful for different aspects of teaching

Qualitative und quantitative Beurteilung des Verhaltens von Jungsauen während eines freiwilligen Annäherungstests

Free farrowing systems are required by organic standards (Commission regulation (EC) 889/2008). However, not only adequate housing design and good management but also sows which are able to rear piglets successfully in those systems are important. Several studies show a relation between approach time during behavioural tests and reproductive traits. So far behavioural traits are not considered when selecting gilts in Austria. The aim of this study was to perform a qualitative and quantitative behavioural assessment during a voluntary approach test at two organic gilt producers which could provide practical tools for behavioural assessment when selecting gilts. A total of 44 gilts was tested in a 3x3m arena and observed when approaching a test person. Qualitatively three components were found: “emotional state”, “proactiveness” and “self-confidence”. The second and third components were significantly related to quantitative parameters. The component “emotional state” may provide additional information. However, it remains to be investigated if this information is related to reproductive performanc

Textile Reinforced Concrete Part I: Process Model for Collaborative Research and Development

The goal of the collaborative research center (SFB 532) >Textile reinforced concrete (TRC): the basis for the development of a new material technology< installed in 1998 at the Aachen University is a complex assessment of mechanical, chemical, economical and productional aspects in an interdisciplinary environment. The research project involves 10 institutes performing parallel research in 17 projects. The coordination of such a research process requires effective software support for information sharing in form of data exchange, data analysis and data archival. Furthermore, the processes of experiment planning and design, modification of material compositions and design parameters and development of new material models in such an environment call for systematic coordination applying the concepts of operational research. Flexible organization of the data coming from several sources is a crucial premise for a transparent accumulation of knowledge and, thus, for a successful research in a long run. The technical information system (TRC-TIS) developed in the SFB 532 has been implemented as a database-powered web server with a transparent definition of the product and process model. It serves as an intranet server with access domains devoted to the involved research groups. At the same time, it allows the presentation of selected results just by granting a data object an access from the public area of the server via internet