3D Particle Tracking Velocimetry Method: Advances and Error Analysis

A full three-dimensional particle tracking system was developed and tested. By using three separate CCDs placed at the vertices of an equilateral triangle, the threedimensional location of particles can be determined. Particle locations measured at two different times can then be used to create a three-component, three-dimensional velocity field. Key developments are: the ability to accurately process overlapping particle images, offset CCDs to significantly improve effective resolution, allowance for dim particle images, and a hybrid particle tracking technique ideal for three-dimensional flows when only two sets of images exist. An in-depth theoretical error analysis was performed which gives the important sources of error and their effect on the overall system. This error analysis was verified through a series of experiments, which utilized a test target with 100 small dots per square inch. For displacements of 2.54mm the mean errors were less than 2% and the 90% confidence limits were less than 5.2 μm in the plane perpendicular to the camera axis, and 66 μm in the direction of the camera axis. The system was used for flow measurements around a delta wing at an angle of attack. These measurements show the successful implementation of the system for three-dimensional flow velocimetry

On imploding cylindrical and spherical shock waves in a perfect gas

The problem of a cylindrically or spherically imploding and reflecting shock wave in a flow initially at rest is studied without the use of the strong-shock approximation. Dimensional arguments are first used to show that this flow admits a general solution where an infinitesimally weak shock from infinity strengthens as it converges towards the origin. For a perfect-gas equation of state, this solution depends only on the dimensionality of the flow and on the ratio of specific heats. The Guderley power-law result can then be interpreted as the leading-order, strong-shock approximation, valid near the origin at the implosion centre. We improve the Guderley solution by adding two further terms in the series expansion solution for both the incoming and the reflected shock waves. A series expansion, valid where the shock is still weak and very far from the origin, is also constructed. With an appropriate change of variables and using the exact shock-jump conditions, a numerical, characteristics-based solution is obtained describing the general shock motion from almost infinity to very close to the reflection point. Comparisons are made between the series expansions, the characteristics solution, and the results obtained using an Euler solver. These show that the addition of two terms to the Guderley solution significantly extends the range of validity of the strong-shock series expansion

Intergenerational Communication

Through dialogue, people from different generations identify similarities and consider how to communicate more effectively to a shared purpose

Erektile Dysfunktion bei Männern in der zweiten Lebenshälfte

Zusammenfassung: Hintergrund: Bisherige Studien zur Prävalenz der erektilen Dysfunktion (ED) zeigen unterschiedliche Ergebnisse. Mit der vorliegenden Studie werden die Häufigkeit und graduelle Ausprägung der ED, deren begünstigende Faktoren sowie das Hilfesuchverhalten der Betroffenen untersucht. Stichprobe und Methodik: Eine Zufallsstichprobe von 628 Deutschschweizer Männern (Durchschnittsalter 61,5Jahre) wurde mittels Fragebogen zur sexuellen Funktionsfähigkeit, Komorbidität und zu ihrem Hilfesuchverhalten befragt. Ergebnisse: 9,6% der Befragten berichten über eine vollständige, 18,0% über eine moderate und 41,4% über eine minimale ED. Alle Grade der Störung nehmen mit dem Alter zu und korrelieren mit somatischer bzw. psychischer Komorbidität sowie Medikamenteneinnahme. Nur 3,2% geben an, schon Mittel zur Verbesserung der Erektionsfähigkeit eingenommen bzw. verwendet zu haben. Schlussfolgerungen: Nur ein kleiner Teil von Männern mit ED sucht ärztliche Hilfe. Sachliche Aufklärung und kompetente ärztliche Beratung von Betroffenen erscheinen angesichts der guten Wirksamkeit von PDE-5-Hemmern angebrach

Social Identities in the Policy Process of Authoritarian Systems.

The integration of the social-psychological social identity approach to policy process research has recently generated new insights on policy-making. Empirical applications for established democracies and multilevel settings such as the European Union have identified five general types of social identities that are relevant for the preferences and behavior of policy actors and their stability and change over time. Social identities are based on joint memberships in social groups, such as organizations, demographic/biographical identities, sectors, locations, and informal opportunities for exchange (which may result in programmatic groups and identities). Some of these social groups, above all pluralistic interest associations and political parties, are directly related to the settings of embedded democracies. This article sheds light on the traveling capacity of the Social Identities in the Policy Process (SIPP) perspective by applying it to the Russian political system. An analysis of policy actors' social identities in two federal ministries shows that in autocracies, interest intermediation, legitimacy, and influence on policy processes run through professional and informal groups when competing organizations and democratic institutions are absent. The results indicate that the SIPP perspective is adaptable to policy processes in different contexts but that the importance of identity types varies

Sparse 3D Point-cloud Map Upsampling and Noise Removal as a vSLAM Post-processing Step: Experimental Evaluation

The monocular vision-based simultaneous localization and mapping (vSLAM) is one of the most challenging problem in mobile robotics and computer vision. In this work we study the post-processing techniques applied to sparse 3D point-cloud maps, obtained by feature-based vSLAM algorithms. Map post-processing is split into 2 major steps: 1) noise and outlier removal and 2) upsampling. We evaluate different combinations of known algorithms for outlier removing and upsampling on datasets of real indoor and outdoor environments and identify the most promising combination. We further use it to convert a point-cloud map, obtained by the real UAV performing indoor flight to 3D voxel grid (octo-map) potentially suitable for path planning.Comment: 10 pages, 4 figures, camera-ready version of paper for "The 3rd International Conference on Interactive Collaborative Robotics (ICR 2018)

Public Policy Research - Born in the USA, at Home in the World?

Public policy emerged as an academic subfield in the United States after the second World War. The theoretical foundations of the discipline are essentially based on analyses of Anglo-Saxon policies and politics and were originally aimed at providing knowledge for the policy process of pluralistic democracies. Given the increasing transfer of the subject and related approaches to other countries, it is necessary to clarify how suitable theories, goals, and methods of policy research are applied in other contexts. What needs to be considered when transferring theories of the policy process, and what can be learned from existing applications of the various approaches in different settings? The compilation of contributions on selected theoretical public policy lenses and their transfer to other countries and regions provides a nuanced answer to these questions.Policy-Forschung ist als wissenschaftliche Teildisziplin nach dem Zweiten Weltkrieg in den USA entstanden. Das theoretische Fundament des Fachs basiert wesentlich auf Analysen angelsächsischer Politik und war ursprünglich darauf ausgerichtet, Wissen für politische Prozesse in pluralistischen Demokratien bereitzustellen. Angesichts der zunehmenden internationalen Ausbreitung des Fachs ist zu klären, inwiefern die Theorien, Ziele und Methoden für Anwendungen in anderen politischen Systemen geeignet sind. Was muss jeweils bei einer Übertragung von Theorien der Policy-Forschung beachtet werden, und was lässt sich aus den bisherigen Anwendungen der verschiedenen Ansätze in unterschiedlichen Kontexten lernen? Die Zusammenstellung von Beiträgen zu ausgewählten Ansätzen und deren Transfer in andere Länder und Regionen gibt eine differenzierte Antwort auf diese Fragen

An organotypic slice culture to study the formation of calyx of Held synapses in-vitro.

The calyx of Held, a large axo-somatic relay synapse containing hundreds of presynaptic active zones, is possibly the largest nerve terminal in the mammalian CNS. Studying its initial growth in-vitro might provide insights into the specification of synaptic connection size in the developing brain. However, attempts to maintain calyces of Held in organotypic cultures have not been fruitful in past studies. Here, we describe an organotypic slice culture method in which calyces of Held form in-vitro. We made coronal brainstem slices with an optimized slice angle using newborn mice in which calyces have not yet formed; the presynaptic bushy cells were genetically labeled using the Math5 promoter. After six to nine days of culturing, we readily observed large Math5-positive nerve terminals in the medial nucleus of the trapezoid body (MNTB), but not in the neighboring lateral superior olive nucleus (LSO). These calyx-like synapses expressed the Ca2+- sensor Synaptotagmin-2 (Syt-2) and the Ca2+ binding protein Parvalbumin (PV), two markers of developing calyces of Held in vivo. Application of the BMP inhibitor LDN-193189 significantly inhibited the growth of calyx synapses, demonstrating the feasibility of long-term pharmacological manipulation using this organotypic culture method. These experiments provide a method for organotypic culturing of calyces of Held, and show that the formation of calyx-like synapses onto MNTB neurons can be preserved in-vitro. Furthermore, our study adds pharmacological evidence for a role of BMP-signaling in the formation of large calyx of Held synapses

Optical properties of cometary particles collected by the COSIMA mass spectrometer on-board <i>Rosetta</i> during the rendezvous phase around comet 67P/Churyumov–Gerasimenko

40 000 collected cometary particles have been identified on the 21 targets exposed by the COSIMA experiment on-board Rosetta to the environment of comet 67P/Churyumov–Gerasimenko from 2014 August to 2016 September. The images of the targets where obtained by the COSIMA microscope (Cosiscope, 13.95 μm pixel−1) with near grazing incidence, which is optimal for the primary objective (detection of collected particles) but very challenging for photometry. However, more than 300 of the collected particles are larger than 100 μm which makes it possible to derive constraints on the optical properties from the distribution of light levels within the particles. Two types of particles collected by COSIMA (compact particles and cluster particles) have been identified in Langevin et al. The best estimate reflectance factors of compact particles range from 10 per cent to 23 per cent. For cluster particles (>90 per cent of large collected particles), the comparison of the signal profiles with illumination from two opposite directions shows that there is scattering within the particles, with a mean free path in the 20–25 μm range, which requires high porosity. The best estimate reflectance factors of cluster particles range from 3 per cent to 22 per cent. This range of reflectance factors overlaps with that obtained from observations of the cometary nucleus at macroscopic scales by OSIRIS and it is consistent with that measured for interplanetary dust particles collected in the stratosphere of the Earth