A tail of plumage colouration: disentangling geographic, seasonal and dietary effects on plumage colour in a migratory songbird

Plumage ornamentation in birds serves critical inter- and intra-sexual signaling functions. While carotenoid-based plumage colouration is often viewed as a classic condition-dependent sexually selected trait, plumage colouration can be influenced by a wide array of both intrinsic and extrinsic factors. Understanding the mechanisms underlying variation in colouration is especially important for species where the signaling function of ornamental traits is complex or when the literature is conflicting. Here, we examined variation in the yellow/orange tail feathers of American redstarts Setophaga ruticilla passing through two migratory stopover sites in eastern North America during both spring and fall migration to assess the role of geographic variation and seasonality in influencing feather colouration. In addition, we investigated whether diet during moult (inferred via stable isotope analysis of feather δ15N and δ13C) influenced plumage colouration. Our findings indicate that geographic variation, season and diet all influence individual differences in American redstart colouration, represented by both traditional and tetrahedral colour variables. The extent to which these factors influence colour expression however is largely dependent on the colour metric under study, likely because different colour metrics reflect different attributes of the feather (e.g. structural components versus pigment deposition). The effects of diet (δ15N) and season were pronounced for brightness, suggesting a strong effect of diet and feather wear/degradation on feather structure. Though hue, a metric that should strongly reflect pigment deposition, also changed from spring to fall, that effect was dependent on age, with only adults experiencing a reduction in ornamentation. Taken together, our results highlight the numerous sources of variation behind plumage coloration and underscores the difficulty of unraveling complex visual signaling systems, such as those in American redstarts

Observation of narrow Autler-Townes components in the resonant response of a dense atomic gas

We have experimentally studied the reflection of a weak probe beam from a dense atomic potassium vapor in the presence of a strong laser field tuned to the atomic resonance transition. We have observed an Autler-Townes doublet under hitherto unexplored conditions, namely that the Rabi frequency induced by the strong laser field is much smaller than the self-broadened width of the resonance transition of the unexcited vapor. We attribute our observation to a reduction of the atomic decoherence by the strong drive field. We present a theoretical model of nonlinear processes in a dense atomic gas to explain the observed results

Comics Telling Refugee Stories

This chapter begins with an indicative survey of comics responding to the current ‘refugee crisis’. The comics in question adopt one of two distinct and established approaches. The first is reportage, usually featuring the author/creator as a central device, while the second re-works and renders testimony in visual form. In their different ways, both contribute to a wider repertoire of positive and sympathetic representations of refugees, offering a counter-point to hostile media and political discourse, often by a focus on the stories of individuals. Mobilizing compassion and moral responses through personal stories of hardship, trauma, tenacity, and survival has long been a tactic of reformist agendas and humanitarian advocacy. By their qualitative difference from dominant forms of factual discourse, comics offer certain advantages. They may also circumvent certain problems associated with photographic representations of suffering. Such comics can nevertheless run the risk of re-producing established victim tropes, and just as with other forms of representation, human-interest angles carry the potential to obscure political dimensions. In an attempt to consider and situate these concerns, the analysis considers the various positions and relations that constitute ‘refugee comics’: subjects, readers, creators, (im)materiality, and circulation

Rekruitment mononukleaerer Phagozyten bei der lebensbedrohlichen Lungentuberkulose Schlussbericht

Available from TIB Hannover: DtF QN1(84,8) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman