Perception of rotating objects by pigeons (Columba livia)

Für mobile Tiere ist sowohl die Fähigkeit, dreidimensionale Objekte als solche wahrzunehmen, als auch das Vermögen, diese trotz Änderung des Blickpunktes, Veränderung der Größe und unterschiedlicher Beleuchtung wieder zu erkennen, von großer Bedeutung. Die Frage, ob ein Tier fähig ist, dreidimensionale Information aus rein zweidimensionalen Darstellungen zu erschließen (wie es zum Beispiel bei Bildern dreidimensionaler Objekte der Fall ist, die auf einem Computer-Monitor präsentiert werden), wurde in den letzten Jahrzehnten der Wahrnehmungsforschung zunehmend zu einem zentralen Thema. Es ist durchaus möglich, dass zum Beispiel Tauben (Columba livia) zweidimensionale Bilder dreidimensionaler Objekte eher als beliebige Ansammlungen zweidimensionaler Merkmale sehen als diese als generalisierte 3-D-Repräsentationen wahrzunehmen. Sollten Tauben aber tatsächlich fähig sein, objektartige Repräsentationen zweidimensionaler Projektionen zu bilden, sollte die „dynamische Präsentation“ (d.h., das schnelle Abbilden aufeinander folgender Objekt-Ansichten) das Wiedererkennen bei diversen Stimulusmodifikationen erleichtern, da dynamische, kontinuierliche Veränderung der Perspektive die Integration einzelner Objektansichten zu einem dreidimensionalen Bild fördern kann. Diese Hypothese wurde in der vorliegenden Diplomarbeit getestet. Dazu wurden Tauben zuerst mit Hilfe einer Go-/No-Go-Prozedur darauf trainiert, zwischen 2-D-Projektionen eines Würfels und einer Pyramide zu unterscheiden. Diese wurden entweder als statische Einzelbilder oder in Rotation um die y-Achse präsentiert. Nachdem sie die Diskriminierungssaufgabe erlernt hatten, wurden den Vögeln in einer Reihe von Generalisationstests neue, modifizierte, Projektionen gezeigt. Die Änderungen betrafen unterschiedliche Objektmerkmale sowie die Art der Rotation, z.B. die Größe, die Oberflächen-Färbung, den Blickwinkel und die Reihenfolge der Einzelbilder einer dynamischen Sequenz. Die Ergebnisse zeigten, dass die meisten Arten von Transformationen das Wiedererkennen klar beeinträchtigten. Im Gegensatz zu einer Studie von COOK & KATZ (1999), die ein vergleichbares experimentelles Design verwendeten, fand ich weder Objektkonstanz über verschiedene Reiztransformationen, noch Anzeichen für einen „Dynamischen Superioritätseffekt“, das heißt, dass die Diskriminierungsleistung bei dynamischer gegenüber statischer Präsentation nicht verbessert war. Auch die Reihenfolge der Einzelbilder innerhalb einer dynamischen Sequenz schien für die Fähigkeit zur Objektunterscheidung nicht von Bedeutung zu sein. Die Fähigkeit, ein Objekt zu erkennen, war stark blickpunktabhängig und war bis zu einem gewissen Grad auch durch Größen- und Farbänderungen beeinflusst. Zusammengenommen legen die Ergebnisse den Schluss nahe, dass die Objektdiskriminierung auf gespeicherter zweidimensionaler Merkmalsinformation beruhte und nicht auf der Verwendung von dreidimensionalen Objektrepräsentationen. Sie bestätigen damit die Ansicht, dass das Wiedererkennen von Objekten von Mechanismen kontrolliert wird, die blickbasiert und nicht objektbasiert sind.Both perceiving the world as consisting of stable, unified, three-dimensional objects and recognising them despite changes in vantage point, size, and lighting conditions are fundamental abilities for all mobile animals. Whether an animal is able to retrieve 3-D information also from flat displays (e.g., 2-D projections of 3-D objects presented on a computer screen) has been a matter of interest in the last decades of research. For instance, pigeons (Columba livia) may perceive two-dimensional pictures of three-dimensional objects simply as random collections of flat, two-dimensional features instead of experiencing them as generalised 3-D representations. If, however, pigeons are indeed able to form object-like representations of two-dimensional displays, “dynamic presentation”, (i.e., presentation of views onto the object in rapid succession) should facilitate recognition across various stimulus modifications, since continuous dynamic change of perspective may help integrating individual views of an object into three-dimensional images. This hypothesis was tested in the current thesis. Pigeons were first trained in a go/no-go procedure to discriminate between 2-D projections of a cube and a pyramid, presented as static images or as rotating around the y-axis. When they had acquired the discrimination the birds were subjected to a series of transfer tests with new, modified, projections. These involved various featural and rotational transformations, such as novel size, altered surface colouration, novel viewpoint, and randomised rotation sequences. The results showed that most types of transformations clearly impaired recognition. In contrast to a study by COOK & KATZ (1999), who used a similar experimental design I could neither find object constancy across various stimulus transformations, nor any indication of a "dynamic superiority effect", i.e., discrimination performance was not improved by dynamic as compared to static presentation, and the order of images within a dynamic sequence was not crucial for object recognition. Furthermore, the ability to recognise an object was found to be strongly viewpoint-dependent and influenced also by modifications in size and colouration to some degree. Together, the results strongly suggest that object discrimination was based on stored 2-D featural information rather than on object-like 3-D representations. They are in line with the view that pigeons’ object recognition is controlled by view-based rather than object-based mechanisms

Using RDF to Describe and Link Social Science Data to Related Resources on the Web

Kramer S, Leahey A, Southall H, Vompras J, Wackerow J. Using RDF to Describe and Link Social Science Data to Related Resources on the Web. DDI Working Paper Series. Dagstuhl, Germany: DDI Alliance; 2012.This document focuses on how best to relate Resource Description Framework (RDF)-described datasets to other related resources and objects (publications, geographies, organizations, people, etc.) in the Semantic Web. This includes a description of what would be needed to make these types of relationships most useful, including which RDF vocabularies should be used, potential link predicates, and possible data sources. RDF provides a good model for describing social science data because it supports formal semantics that provide a dependable basis for reasoning about the meaning of an RDF expression. In particular, it supports defined notions of entailment which provide a basis for defining reliable rules of inference in RDF data. Our findings are discussed in the context of social science data and more specifically, how to leverage existing metadata models to use alongside linked data. We provide a case for leveraging the Data Documentation Initiative (DDI) to enable semantic linking of social science data to other data and related resources on the Web. This document is organized into five use cases, which we consider in turn. Use cases include: linking related publications to data, linking data about people and organizations to research data, linking geography, linking to related studies, and linking data to licenses. We briefly discuss emerging or known issues surrounding the potential use of linked data within each of the defined use cases. Following these, we list more topics that could develop into additional use cases. Appendix A lists elements from the DDI-Codebook and DDI-Lifecycle specifications that are relevant to each use case

Calcarides A–E, Antibacterial Macrocyclic and Linear Polyesters from a Calcarisporium Strain

Bioactive compounds were detected in crude extracts of the fungus, Calcarisporium sp. KF525, which was isolated from German Wadden Sea water samples. Purification of the metabolites from the extracts yielded the five known polyesters, 15G256α, α-2, β, β-2 and π (1–5), and five new derivatives thereof, named calcarides A–E (6–10). The chemical structures of the isolated compounds were elucidated on the basis of one- and two-dimensional NMR spectroscopy supported by UV and HRESIMS data. The compounds exhibited inhibitory activities against Staphylococcus epidermidis, Xanthomonas campestris and Propionibacterium acnes. As the antibacterial activities were highly specific with regard to compound and test strain, a tight structure-activity relationship is assumed

FR1.2: Valuing control over income and workload: A field experiment in Rwanda

Agricultural development programs often aim to enhance women's control over income, but as an unintended negative consequence, these programs may increase women's already heavy work burden. By means of a lab-in-the-field experiment with 1,000 men and women in rural Rwanda, we elicit men's and women's valuations of control over income, changes in workload, and trade-offs between them. Survey data indicate that women in this setting are less empowered than men. Control over the use of income contributes less to disempowerment than high workloads. Moreover, in the experiment, we find that women are willing to sacrifice more household income to gain control over income than their husbands, but both women and men are willing to forgo even more personal and household income with the aim of reducing their workload. This indicates that in the setting where the experiment was conducted, agricultural development programs that introduce time-saving practices and technologies have potentially greater welfare impacts for both women and men than programs increasing women's control over monetary resources