Methods for Estimating Mass-Sensitive Observables of Ultra-High Energy Cosmic Rays using Artificial Neural Networks

Die ultrahochenergetische kosmische Strahlung besteht aus den energiereichsten, natürlich vorkommenden Teilchen, die der Menschheit bekannt sind. Da sie zwei Größenordnungen jenseits der Energieskala der derzeitigen Generation von Teilchenbeschleunigern liegt, sind die Fragen, wie die kosmische Strahlung ihre Energie erhält und woher sie stammt, noch immer ein Mysterium. Darüber hinaus stellt der Überschuss an Myonen in den Zerfallsprodukten der ultrahochenergetischen kosmischen Strahlung in der Erdatmosphäre auch unser Verständnis der hadronischen Wechselwirkungen bei höchsten Energien in Frage. Um die Rätsel der kosmischen Strahlung zu lösen, ist es unerlässlich, die Massen der einfallenden kosmischen Strahlen zu bestimmen. Die Trennung der schweren kosmischen Strahlung von der leichten kosmischen Strahlung ermöglicht Untersuchungen der Einfallsrichtungen, um minimal abgelenkte kosmische Strahlung mit potenziellen Quellen in Verbindung zu bringen. Da die Anzahl der Nukleonen direkt mit der Anzahl der erzeugten Myonen zusammenhängt, können wir dadurch außerdem die Modelle der hadronischen Wechselwirkung anhand realer Messungen überprüfen. Aufgrund des geringen Flusses der ultrahochenergetischen kosmischen Strahlung sind große Detektoren für den indirekten Nachweis der kosmischen Strahlung erforderlich, um genügend Statistik zu erhalten. Das Pierre-Auger-Observatorium ist das größte Observatorium für kosmische Strahlung auf der Welt und deckt einen Fläche von über 3000 km$^2$ ab. Der Zerfall eines hochenergetischen Teilchens in der Atmosphäre löst eine Kaskade von Sekundärteilchen aus, die als Luftschauer bezeichnet wird. Das Observatorium ist speziell für den Nachweis von solchen Luftschauern konzipiert worden. Dabei wird die Atmosphäre als Kalorimeter genutzt, um die Entwicklung der Schauer in Längsrichtung mit Fluoreszenzdetektoren zu messen. Zusätzlich wird ein Oberflächendetektor mit regelmäßig angeordneten Detektorstationen eingesetzt, um die Menge der erzeugten Sekundärteilchen zu messen. Diese Sekundärteilchen werden üblicherweise als Schauer-Fußabdruck bezeichnet. Die zunehmende Popularität künstlicher neuronaler Netze in jüngster Zeit hat Physikern neue, einfach zu handhabende Werkzeuge gegeben, um physikalische Probleme datengesteuert anzugehen. Die Verwendung neuronaler Netze bietet die Möglichkeit, detaillierte Daten, wie z. B. Schauer-Fußabdrücke, mit physikalischen Beobachtungsgrößen, wie z. B. der Energie eines Luftschauers, in Beziehung zu setzen, ohne dass ein analytisches Modell erstellt werden muss. Das Hauptziel dieser Arbeit ist die Untersuchung von Methoden, die auf neuronalen Netzen basieren, um aus den Daten des Oberflächendetektors des Pierre-Auger-Observatoriums Informationen zu extrahieren, die mit der Masse der kosmischen Strahlung korrelieren. Um dies zu erreichen, habe ich zwei verschiedene Ansätze in Betracht gezogen und die Nützlichkeit der Verwendung neuronaler Netze untersucht. Dabei basiert der erste Ansatz auf der Extraktion des Myonengehalts in jeder Station des Oberflächendetektors und der zweite Ansatz auf der Messung des gesamten Schauer-Fußabdrucks. Anhand von Monte-Carlo-Simulationsstudien habe ich den ersten Ansatz zugunsten des zweiten verworfen, da letzterer vielversprechendere Ergebnisse lieferte. Aus dieser Simulationsstudie habe ich drei verschiedene neuronale Netze ausgewählt, die für die Vorhersage der Tiefe des Schauer-Maximums, des relativen Myonengehalts und der logarithmischen Masse von Schauer-Fußabdrücken trainiert wurden. In einem letzten Schritt benutzte ich die Netzwerke, um die Massenzusammensetzung der ultrahochenergetischen kosmischen Strahlung aus Messungen vom Pierre Auger Observatorium zu bestimmen

Timing is crucial for consequences of migratory connectivity

Migratory connectivity can have important consequences for individuals, populations and communities. We argue that most consequences not only depend on which sites are used but importantly also on when these are used and suggest that the timing of migration is characterised by synchrony, phenology, and consistency. We illustrate the importance of these aspects of timing for shaping the consequences of migratory connectivity on individual fitness, population dynamics, gene flow and community dynamics using examples from throughout the animal kingdom. Exemplarily for one specific process that is shaped by migratory connectivity and the timing of migration – the transmission of parasites and the dynamics of diseases – we underpin our arguments with a dynamic epidemiological network model of a migratory population. Here, we quantitatively demonstrate that variations in migration phenology and synchrony yield disease dynamics that significantly differ from a time‐neglecting case. Extending the original definition of migratory connectivity into a spatio‐temporal concept can importantly contribute to understanding the links migratory animals make across the globe and the consequences these may have both for the dynamics of their populations and the communities they visit throughout their journeys

First records of complete annual cycles in water rails Rallus aquaticus show evidence of itinerant breeding and a complex migration system

In water rails Rallus aquaticus, northern and eastern populations are migratory while southern and western populations are sedentary. Few details are known about the annual cycle of this elusive species. We studied movements and breeding in water rails from southernmost Norway where the species occurs year-round. Colour-ringed wintering birds occurred only occasionally at the study site in summer, and vice versa. Geolocator tracks revealed that wintering birds (n = 10) migrated eastwards in spring to breed on both sides of the Baltic Sea, whereas a single breeding bird from the study site wintered in north Italy. Ambient light records of geolocator birds further indicated that all but one incubated 2–4 clutches per season. By combining information on incubation and movement, we found evidence for itinerant breeding in three individual birds: After a first breeding attempt (one did not incubate), all moved 129–721 km to breed again. This behaviour is rarely recorded in birds and was unexpected because the water rail is described as monogamous with both parents caring for eggs and chicks. The study greatly improves our knowledge about the annual cycle and reproduction in water rails. However, more studies are warranted to evaluate the generality of our findings and causes of breeding itinerancy.acceptedVersio

Year-round tracking of small trans-Saharan migrants using light-level geolocators

Since 1899 ringing (or banding) remained the most important source of information about migration routes, stopover sites and wintering grounds for birds that are too small to carry satellite-based tracking systems. Despite the large quantity of migrating birds ringed in their breeding areas in Europe, the number of ring recoveries from sub-Saharan Africa is very low and therefore the whereabouts of most small bird species outside the breeding season remain a mystery. With new miniaturized light-level geolocators it is now possible to look beyond the limits of ring recovery data. Here we show for the first time year round tracks of a near passerine trans-Saharan migrant, the European Hoopoe (Upupa epops epops). Three birds wintered in the Sahel zone of Western Africa where they remained stationary for most of the time. One bird chose a south-easterly route following the Italian peninsula. Birds from the same breeding population used different migration routes and wintering sites, suggesting a low level of migratory connectivity between breeding and wintering areas. Our tracking of a near passerine bird, the European Hoopoe, with light-level geolocators opens a new chapter in the research of Palaearctic-African bird migration as this new tool revolutionizes our ability to discover migration routes, stopover sites and wintering grounds of small birds

Sex recognition in brown skuas: do acoustic signals matter?

Bird vocalisations are often essential for sex recognition, especially in species that show little morphological sex dimorphism. Brown skuas (Catharacta antarctica lonnbergi), which exhibit uniform plumage across both sexes, emit three main calls: the long call, the alarm call and the contact call. We tested the potential for sex recognition in brown skua calls of 42 genetically sexed individuals by analysing 8-12 acoustic parameters in the temporal and frequency domains of each call type. For every call type, we failed to find sex differences in any of the acoustic parameters measured. Stepwise discriminant function analysis (DFA) revealed that sexes cannot be unambiguously classified, with increasing uncertainty of correct classification from contact calls to long calls to alarm calls. Consequently, acoustic signalling is probably not the key mechanism for sex recognition in brown skua

Design of dual ligands using excessive pharmacophore query alignment : from 7th German Conference on Chemoinformatics: 25 CIC-Workshop Goslar, Germany, 6 - 8 November 2011

Dual- or multi-target ligands have gained increased attention in the past years due to several advantages, including more simple pharmacokinetic and phamarcodynamic properties compared to a combined application of several drugs. Furthermore multi-target ligands often possess improved efficacy. We present a new approach for the discovery of dual-target ligands using aligned pharmacophore models combined with a shape-based scoring. Starting with two sets of known active compounds for each target, a number of different pharmacophore models is generated and subjected to pairwise graph-based alignment using the Kabsch-Algorithm. Since a compound may be able to bind to different targets in different conformations, the algorithm aligns pairs of pharmacophore models sharing the same features which are not necessarily at the exactly same spatial distance. Using the aligned models, a pharmacophore search on a multi-conformation-database is performed to find compounds matching both models. The potentially “dual” ligands are scored by a shape-based comparison with the known active molecules using ShaEP. Using this approach, we performed a prospective fragment-based virtual screening for dual 5-LO/sEH inhibitors. Both enzymes play an important role in the arachidonic acid cascade and are involved in inflammatory processes, pain, cardiovascular diseases and allergic reactions. Beside several new selective inhibitors we were able to find a compound inhibiting both enzymes in low micromolar concentrations. The results indicate that the idea of aligned pharmacophore models can be successfully employed for the discovery of dual-target ligands

Primer registro del género Anogramma Link (Pteridaceae) en Chile

The genus Anogramma Link (Pteridaceae), by means of Anogramma leptophylla (L.) Link is reported for the first time in Chile, from a collection recently made in the Andes Mountains, Maule Region.The genus Anogramma Link (Pteridaceae), by means of Anogramma leptophylla (L.) Link is reported for the first time in Chile, from a collection recently made in the Andes Mountains, Maule Region