Structural Stability: On the Prerequisites of Nonviolent Conflict Management

The concept of “structural stability” has been gaining prominence in development policy circles. In the EU’s and the OECD Development Assistance Committee’s (OECD DAC) understanding, it describes the ability of societies to handle intra-societal conflict without resorting to violence. This study investigates the preconditions of structural stability and tests their mutual interconnections. Seven dimensions are analyzed: (1) long-term economic growth, (2) environmental security, (3) social equality, (4) governmental effectiveness, (5) democracy, (6) rule of law, and (7) inclusion of identity groups. The postulated mutual enhancement of the seven dimensions is plausible but cannot be proven. The most significant positive relationship appears between “democracy” and “rule of law,” respectively, on the one hand and the dependent variable “violence/ human security” on the other hand. This points to the usefulness of the political concept of structural stability to promote development policy agendas in this area at least. Applications that reach beyond these initial findings will, however, require further research.Structural stability, violence, human security, development aid, conflict management, prerequisites of nonviolence

Zweifrequenz Magnetic-Particle-Imaging-Scanner - Hardware für mobilityMPI

Magnetic Particle Imaging (MPI) ist eine neue tomographische Bildgebungsmethode, welche magnetische Nanopartikel als Marker nutzt und potentielle Anwendungsmöglichkeiten in der Medizin und medizinischen Forschung bietet. Durch seine Auflösung im mm-Bereich und seine hohe zeitliche Auflösung ist es für viele Anwendungen geeignet. Da MPI ohne ionisierende Strahlung arbeitet, bietet eine Substitution von radiologischen Untersuchungen Vorteile für Patient und medizinisches Personal. Eine Herausforderung ist die Entwicklung von Anwendungsmöglichkeiten, die über die Fähigkeiten der etablierten Methoden hinausgehen. Ein möglicher Vorteil von MPI ist die Nutzung von Nanopartikeln, welche z.B. durch Funktionalisierung der Oberfläche kontrolliert mit ihrer Umgebung interagieren können. Durch das Ausnutzen der Partikeldynamik können diese Interaktionen magnetisch mit MPI gemessen und eine räumliche Darstellung des Partikelzustands gewonnen werden. Die vorliegende Arbeit beschreibt die Entwicklung und Anwendung eines MPI-Scanners, welcher speziell für die Demonstration und Erforschung der funktionalen Bildgebungsmöglichkeiten mit MPI unter Ausnutzung der Mobilitätsinformation der Partikel entworfen wurde. Dieses Konzept, welches als mobility-MPI (mMPI) bezeichnet wird, kann durch verschiedene Verfahren unter Ausnutzung der Brownschen Relaxation realisiert werden. Ein Verfahren ist die Verwendung zweier Anregungsfrequenzen, was die Separation der Partikeldynamik von der räumlichen Verteilung ermöglicht. Da aktuelle MPI Scanner Sende- und Empfangsschaltungen besitzen, welche an die Anregungsfrequenz angepasst sind, erfordert das Mehrfrequenz-mMPI Hardwareerweiterungen gegenüber konventionellen Scannern. Die vorliegende Arbeit beschreibt detailliert das Design und die Konstruktion eines Magnetic Particle Spectrometers und eines mMPI-Systems und ihrer Komponenten. Mehrere Entwurfsverfahren, wie z.B. eine Methode zur präzisen Vorhersage der parasitären Effekte bei Spulen, wurden im Zuge des Design-Prozesses entwickelt. Erwähnenswert ist ebenfalls das Design der Sende- und Empfangsfilter, welche hohe Dämpfungswerte im Sperrbereich bei guter Linearität liefern. Die Entwicklung einer volldifferentiellen Empfangsspule ist ein weiterer interessanter Aspekt. Der neue Scanner wurde ausgehend von konventionellen ein- und zweidimensionalen MPI-Bildern genutzt, um die Eignung von MPI für die räumlich aufgelöste funktionale Bildgebung mittels Partikeldynamik zu zeigen.Magnetic Particle Imaging (MPI), being a new tomographic imaging modality based on magnetic nanoparticle tracers, offers potential applications in medicine and medical research. Possessing spatial resolution in the millimeter range and high temporal resolution, it is well suited for many applications. Since MPI doesn't rely on ionizing radiation, substitution of radiological methods by MPI benefits the safety of patients and medical staff. One of the challenges MPI faces is to provide capabilities that surpass what is currently possible with tracer based imaging systems. A possible advantage of MPI is the presence of nanoparticle tracers that can be modified to interact in well defined ways with their environment through surface functionalization. By exploiting particle dynamics, these interactions can be measured magnetically and can provide a spatially resolved map of particles states, enabling quantitative, functional imaging. This work describes the development and application of a MPI scanner designed specifically to demonstrate and further research the functional imaging capability of MPI through the measurement of particle mobility. This concept, called moblity MPI (mMPI), can be realized based on the Brownian relaxation mechanism. One possible technique involves the use of multiple excitation frequencies, that can be used to separate information on the spatial distribution from particle dynamics. Since the particle relaxation is inherently dependent on the excitation frequency, acquiring the same image at several drive frequencies provides the additional data required for functionally and spatially resolved MPI. Since current MPI scanners rely on transmit and receive chains tuned to the excitation frequency, the scanner hardware needs to be adapted. This thesis describes in detail the design and construction of a MPS and a mMPI system and their components. Several design techniques, such as a method for the accurate prediction of coil parasitics, have been developed for this task. Other noteworthy aspects are the design of transmit and receive filters, offering high stop band attenuation and good linearity. The development of a fully differential receive coil completes the effort to provide a system suitable for the demonstration of mMPI. After acquiring conventional one- and two-dimensional MPI images, the new scanner was used to demonstrate the capability of MPI to provide spatially resolved information on particle mobility

Optimization of Synthetic Inertial Response from Wind Power Plants

In this paper the emphasis is on the optimization of synthetic inertial response of wind power plants (WPPs) for power systems with high wind power penetration levels, considering different wind speed operating conditions. The synthetic inertial response of wind power plants can play an important role in the resilience of future power systems with low inertia during large frequency disturbances. In order to investigate this role, a generic optimization methodology employing the genetic algorithm is proposed, taking into consideration the frequency nadir, second frequency dip, and time to reach the quasi–steady-state frequency. This optimization methodology comprehends the inertial response capability of WPPs and the frequency control dynamics of the power system. Accordingly, offline parameter tuning of synthetic inertial response is performed at the power system level with the proposed methodology. Based on the optimization results, the relevant aspects to be considered by transmission system operators and wind power plant developers in the process of designing and planning synthetic inertia are identified and analyzed. Additionally, sensitivity analyses are carried out to assess the impact of synthetic inertial response parameters on power system frequency control performance under different contingencies and wind power penetration levels

Magnetic Field Sensor Calibration for Attitude Determination

The presented work aims to give an overview of different calibration methods for magnetic field sensors, which are used for attitude determination. These methods are applicable in the field without any additional equipment. However, sometimes they require simplification assumptions. The paper addresses the validity of these assumptions, the accuracy and efficiency of the methods and the influence of the calibration error on the orientation estimation. Both simulations and measurements are used for evaluation. The measurements are performed using a GNSS multi-antenna system, providing an orientation reference (roll, pitch, yaw) without unknown external magnetic disturbances and with a sufficient accuracy (about 0.5 degrees). It is shown in simulations, that a full calibration of the sensor (including soft and hard iron disturbances by nearby materials) is possible without any additional equipment. However, experiments show, that some parts of the full calibration procedure are sensitive to an accurate execution of the necessary movements, which may lead to calibration errors in the same order of magnitude as a simplified method, which ignores the presence of soft iron disturbances

Educational activities in progress from PISA - the example Bremen. About the changing legitimization of measurement instruments used in the studies to measure efficiency

Im vorliegenden Aufsatz [wird] der Frage nachgegangen, ob die PISA-Ergebnisse tatsächlich verursachend für die Einführung von Vergleichsarbeiten, Leistungstest und zentralen Prüfungen gewesen sind. Dazu wird die These vertreten, dass die Ergebnisse der PISA-Studie zwar als Begründung für die Einführung solcher Maßnahmen bemüht wurden, dass de facto aber die politischen (Vor-)Entscheidungen vorher getroffen waren, so dass PISA lediglich als nachträgliches Argument dazu diente, die Realisierung dieser Vorhaben zu beschleunigen, zu bestärken oder auszuweiten. Es wird also behauptet, dass PISA auch dazu genutzt wurde, schon länger geplante standardisierte Leistungsüberprüfungen (Vergleichsarbeiten, zentrale Prüfungen) durchzusetzen und zu legitimieren. Der empirische Nachweis der in der These aufgestellten Behauptung fußt auf Ergebnissen aus dem Forschungsprojekt "Ministerielle Steuerung und Leistungsvergleichsstudien (MiSteL)", das [in dem Artikel] kurz skizziert wird. Im Anschluss daran werden einige Befunde dieser Studie expliziert. Dazu wird mit der Diskussion um standardisierte Leistungsüberprüfungen in Bremen ein Fall exemplarisch dargestellt. Die landesspezifischen Befunde werden sodann in einen größeren Zusammenhang gestellt, indem auf die Ergebnisse aus zwei weiteren Fallstudien (Brandenburg, Thüringen) verwiesen wird. (DIPF/Orig.)The example of Bremen shows, that instead of remaining an instrument for comparison studies concerning achievement, the instrument changed its function: Now it serves to legitimize long term planned projects. (DIPF/Orig.

Impairments of Biological Motion Perception in Congenital Prosopagnosia

Prosopagnosia is a deficit in recognizing people from their faces. Acquired prosopagnosia results after brain damage, developmental or congenital prosopagnosia (CP) is not caused by brain lesion, but has presumably been present from early childhood onwards. Since other sensory, perceptual, and cognitive abilities are largely spared, CP is considered to be a stimulus-specific deficit, limited to face processing. Given that recent behavioral and imaging studies indicate a close relationship of face and biological-motion perception in healthy adults, we hypothesized that biological motion processing should be impaired in CP. Five individuals with CP and ten matched healthy controls were tested with diverse biological-motion stimuli and tasks. Four of the CP individuals showed severe deficits in biological-motion processing, while one performed within the lower range of the controls. A discriminant analysis classified all participants correctly with a very high probability for each participant. These findings demonstrate that in CP, impaired perception of faces can be accompanied by impaired biological-motion perception. We discuss implications for dedicated and shared mechanisms involved in the perception of faces and biological motion