Effectiveness of different types of block ramps for fish upstream movement

Rivers are worldwide highly fragmented due to human impacts. This fragmentation has a negative effect on fish movement and dispersal. Many artificial barriers such as river bed sills and small weirs are nowadays replaced by block ramps in order to reestablish longitudinal connectivity for fish in rivers and streams. We studied the upstream passage of several fish species on different types of block ramps with slopes between 3.6 and 13.4%. We conducted translocation experiments in the field based on mark-recapture and on the use of PIT-tags. Temporal movement patterns were observed by an instream antenna. Hydraulic and morphological characteristics of block ramps were measured and compared with fish passage efficiency. Our results clearly showed that upstream passage efficiency differs between fish species, size classes and block ramps. We observed that brown trout (Salmo trutta fario) performed better than bullhead (Cottus gobio) and several cyprinid species on the same block ramps. Passage efficiency of brown trout and chub (Leuciscus cephalus) was size-selective, with small-sized individuals being less successful. For brown trout, size-selectivity became more relevant with increasing slope of ramp. We conclude that block ramps with slopes of >5% are ineffective for the small-sized cyprinid species and that vertical drops within step-pool ramps can hinder successful upstream passage of bullhea

Klassifizierung unbekannter Proben ökologischer und konventioneller Herkunft mittels FAS anhand von Trainingsdaten aus dem Vorjahr

Different sorts of apples coming from pairs of organic/conv. producers of different locations in Switzerland and Germany were retrospectively investigated in 2004 and prospectively classified in 2005 based on data measured by fluorescence-excitation-spectroscopy (FES) and subsequent discriminant analysis. The result was in 8 of 9 cases a correct identification of the method of production. In one case the data showed no difference

On the second Tate-Shafarevich group of a 1-motive

We prove finiteness results for Tate--Shafarevich groups in degree 2 associated with 1--motives, rely them to Leopoldt's conjecture, and present an example of a semiabelian variety with an infinite Tate--Shafarevich group in degree 2. We also establish an arithmetic duality theorem for 1--motives over number fields which complements earlier results of Harari and Szamuely in this direction.Comment: 28 page

Le pouvoir des images : des médias visuels aux médias sociaux

De la Bible au Prince de Machiavel, les lettres et les livres ont constitué le vecteur privilégié du pouvoir – le fondement mystique de la force de loi, pour paraphraser un titre de Jacques Derrida. L’empereur Gaius Julius Caesar Octavianus, connu sous le nom d’Auguste, aurait le premier découvert le pouvoir des images, déployant une stratégie inédite afin d’assurer sa domination absolue. En élevant de nombreux édifices et en multipliant ses portraits en tous lieux et sur tous supports, il es..

Patterns of recruitment and injury in a heterogeneous airway network model

In respiratory distress, lung airways become flooded with liquid and may collapse due to surface-tension forces acting on air-liquid interfaces, inhibiting gas exchange. This pa- per proposes a mathematical multiscale model for the mechanical ventilation of a network of occluded airways, where air is forced into the network at a fixed tidal volume, allowing investigation of optimal recruitment strategies. The temporal response is derived from mechanistic models of individual airway reopening, incorporating feedback on the airway pressure due to recruitment. The model accounts for stochastic variability in airway di- ameter and stiffness across and between generations. For weak heterogeneity, the network is completely ventilated via one or more avalanches of recruitment (with airways recruited in quick succession), each characterised by a transient decrease in the airway pressure; avalanches become more erratic for airways that are initially more flooded. However, the time taken for complete ventilation of the network increases significantly as the network becomes more heterogeneous, leading to increased stresses on airway walls. The model predicts that the most peripheral airways are most at risk of ventilation-induced damage. A positive-end-expiratory pressure (PEEP) reduces the total recruitment time but at the cost of larger stresses exerted on airway walls

Simulative performance evaluation for the design of distributed systems

Performance-Evaluationen sind normalerweise Messungen, mit denen eine Verarbeitungsgeschwindigkeit eines Systems oder einer Komponente nachgemessen wird. Die Performance verteilter Systeme wird häufig erst untersucht, wenn die Systeme in einer Testumgebung oder sogar in der produktiven Umgebung eingesetzt werden. Erst dann sind die realen Benutzungsszenarien, Datenmengen, Belastungen und Störeffekte vorhanden, also die Messungen realistisch. Viele moderne Ansätze erlauben die Realisierung aller möglichen Design-Konzepte für Verteilte Systeme. Nur wenige davon adressieren den Performance- Aspekt nachhaltig. In dieser Arbeit präsentieren wir einen Ansatz, der erlaubt, aus Sicht der Performance Aussagen über Nützlichkeit und Konsequenzen von Design-Konzepten im Gesamtzusammenhang zu machen, bevor ein System realisiert oder geändert wird. Es geht dabei um eine Ergänzung im System-Design und nicht um eine Überprüfung nach der Fertigstellung eines Systems. Kernpunkt unseres ansatzes ist ein Evaluationsprozess, der eng mit dem Designprozess für ein verteiltes System zu integrieren ist. Das Designmodell wird in ein Evaluationsmodell übernommen und dort untersucht. Es geht darum, vor der Realisierung Aussagen über die Ressourcennutzung, Antwortzeiten und andere Indikatoren für die Leistung zu machen und zu überprüfen, ob die gewählte Systemarchitektur den Anforderungen entspricht. Dabei können verschiedene Benutzungsszenarien zum Einsatz kommen. Ist ein Evaluationsmodell erstellt, so kann mit verschiedenen Strategien Wissen darüber gewonnen werden. Wir stellen verschiedene Strategien in dieser Dissertation vor. Das sogenannte Cold Start Protokoll ist z.B. eine einfache Strategie zur effizienten Ermittlung des Durchsatzmaximums für einfache Fälle. Ist die Systembenutzung komplex, so kommen kompliziertere Strategien zur Anwendung, die jedoch zumeist auf die einfacheren Strategien zurückgreifen. Die Strategien sind auch Kern unserer Forschung. Mit ihnen untersuchen wir Hypothesen und führen Lernprozesse durch. Sie erlauben einem Evaluationssystem, ohne permanente Steuerung durch einen Experten Standardaufgaben der Performanceevaluation durchzuführen. Damit wird Designern ein Mittel in die Hand gegeben, Designentscheidungen mittels Evaluation zu überprüfen und Alternativen direkt zu vergleichen. Das geht sogar bis zu einfachen Untersuchungen der Skalierbarkeit. Realisiert werden die Strategien durch Variation, indem gewisse Parameter eines Modells durch die Strategien variiert werden können. Variationen beziehen sich auf durch Benutzer festgelegte Modellparameter. Die Strategien bestimmen einzelne Konfigurationen, für die dann jeweils ein Simulationsexperiment durchgeführt wird. Als Resultat der Simulationsreihe kann eine Strategie dann die Effekte der Variation ermitteln. Schliesslich werden Resultate in geeigneter Form, zumeist graphisch, präsentiert. Diese Darstellung umfasst meist die Resultate vieler Experimente. Ihre Aufgabe ist, die Interpretation zu erleichtern und die Benutzer darin zu unterstützen, die richtigen Schlussfolgerungen aus der Evaluation zu ziehen. Performance evaluations have mostly been measurements to determine the processing speed of a system or component. For the case of distributed systems the performance is often only tested when the system is used in either a test environment or even in the productive environment. It is only then that real usage scenarios, real amounts of data, and real effects of work load and disturbances are present and thus measurements realistic. Many modern approaches allow the realization of all kinds of design conceptions for distributed systems. Only few of them seriously consider the performance aspect. In this thesis we present an approach that allows statements about usefulness and consequences of design conceptions for a system from the performance perspective even before the system has been realized or changed. The intention is a complement for systems design, not an examination after completion of a system's realization. The core of our approach is an evaluation process that is closely integrated with the design process for a distributed system. The design model created there is translated into an evaluation model to be examined. The aim is to allow statements about resource usage, response time, and other performance indicators for the system's performance to find out whether the chosen system architecture can satisfy the requirements. Different usage scenarios can be used to do that. Once an evaluation model is created, evaluation strategies are applied to gain knowledge about its performance. We present different strategies in this dissertation thesis. The so-called Cold Start Protocol, e.g., is a simple strategy to efficiently determine a throughput maximum for simple cases. More complex strategies have to be applied if the system usage is complex; they typically rely on the more simple strategies for their own realization. The strategies are the core of our research. We use them to test hypotheses and to perform learning processes. They allow an evaluation system to execute standard tasks of performance evaluation without necessarily being controlled by an expert. A tool implementing these strategies is a means for designers to examine their design decisions by executing an evaluation, and even to compare alternatives directly. Even simple examinations of scalability are possible with this approach. The strategies are realized using variation of specific parameters of the evaluation models. The variations refer to user-determined model parameters. The strategies determine individual configurations for which a simulation experiment is executed. As a result of the simulation series, the strategies are able to determine the effects of the variation. Finally, the results are presented in a suitable way, most as graphic representation. This representation in most cases contains the results of multiple experiments. It is aimed to facilitate the interpretation, and to support the users to draw the right conclusions from the evaluation

Particle Energization in an Expanding Magnetized Relativistic Plasma

Using a 2-1/2-dimensional particle-in-cell (PIC) code to simulate the relativistic expansion of a magnetized collisionless plasma into a vacuum, we report a new mechanism in which the magnetic energy is efficiently converted into the directed kinetic energy of a small fraction of surface particles. We study this mechanism for both electron-positron and electron-ion (mi/me=100, me is the electron rest mass) plasmas. For the electron-positron case the pairs can be accelerated to ultra-relativistic energies. For electron-ion plasmas most of the energy gain goes to the ions.Comment: 7 pages text plus 5 figures, accepted for publication by Physical Review Letter