Near-field thermal imaging of nanostructured surfaces

We show that a near-field scanning thermal microscope, which essentially detects the local density of states of the thermally excited electromagnetic modes at nanometer distances from some material, can be employed for nanoscale imaging of structures on that material's surface. This finding is explained theoretically by an approach which treats the surface structure perturbatively

Übersicht über die Bestände des Universitätsarchivs Tübingen : 1335 - 2013

Die Übersicht über die Bestände des Universitätsarchivs Tübingen verzeichnet die im Archiv verwahrten Bestände auf der obersten Ebene. Die einzelnen Provenienzstellen/abliefernden Stellen werden in ihrer historischen Entwicklung kurz dargestellt und die Unterlagen, die zu dieser Stelle im Universitätsarchiv vorhanden sind, summarisch aufgeführt. Zu den in dieser Übersicht verzeichneten Beständen gibt es im Universitätsarchiv und auf dessen Webseite detaillierte Findbücher, in denen die Archivalien einzeln verzeichnet sind

Reproduction potentiated in nematodes (Caenorhabditis elegans) and guppy fish (Poecilia reticulata) by adding a synthetic peptide to their aqueous environment

This document is the Accepted Manuscript version of an article accepted for publication in Journal of Experimental Biology following peer review. The final, definitive version of this paper is available online at doi: https://doi.org/10.1242/jeb.113837.Ambient exposure to a short synthetic peptide has enhanced fecundity (number of offspring) in invertebrates and vertebrates, ostensibly by disinhibiting reproduction. In separate experiments nematodes (Caenorhabditis elegans) and guppy fish (Poecilia reticulate) were exposed via their aqueous environment to a dissolved synthetic hexamer peptide, IEPVFT (EPL036), at a concentration of 1 μM. In the case of the worms peptide was added to their aqueous buffer daily throughout the experiment (14 days); in the guppies peptide administration was on the first 15 alternate days in a 50-week experiment. Fecundity rose by 79% among the worms. The number of descendants of the treated guppies was more than four times that of controls by Week 26 (103 vs 25), with double the estimated biomass. It was deduced that treated females bred earlier, at a smaller size, and had larger brood sizes. The total number of fish in the control tank had caught up by termination, but biomass continued to lag the test tank. There were no overt signs of toxicity among either the worms or the fish. Bioinformatics has been unilluminating in explaining these results in terms of mimicry of an endogenous regulator. A mass spectrometric campaign to identify a receptor proved inconclusive. Molecular modelling in silico indicated unexpectedly that the 6mer EPL036 might be acting as an antagonist, to pro-fecundity effect; that is, as an inhibitor of an inhibitor. This suggests that there awaits discovery an evolutionarily conserved reproductive inhibitor and its (anti-fecundity) receptor.Peer reviewe

The brain's supply and demand in obesity

During psychosocial stress, the brain demands extra energy from the body to satisfy its increased needs. For that purpose it uses a mechanism referred to as “cerebral insulin suppression” (CIS). Specifically, activation of the stress system suppresses insulin secretion from pancreatic beta-cells, and in this way energy—particularly glucose—is allocated to the brain rather than the periphery. It is unknown, however, how the brain of obese humans organizes its supply and demand during psychosocial stress. To answer this question, we examined 20 obese and 20 normal weight men in two sessions (Trier Social Stress Test and non-stress control condition followed by either a rich buffet or a meager salad). Blood samples were continuously taken and subjects rated their vigilance and mood by standard questionnaires. First, we found a low reactive stress system in obesity. While obese subjects showed a marked hormonal response to the psychosocial challenge, the cortisol response to the subsequent meal was absent. Whereas the brains of normal weight subjects demanded for extra energy from the body by using CIS, CIS was not detectable in obese subjects. Our findings suggest that the absence of CIS in obese subjects is due to the absence of their meal-related cortisol peak. Second, normal weight men were high reactive during psychosocial stress in changing their vigilance, thereby increasing their cerebral energy need, whereas obese men were low reactive in this respect. Third, normal weight subjects preferred carbohydrates after stress to supply their brain, while obese men preferred fat and protein instead. We conclude that the brain of obese people organizes its need, supply, and demand in a low reactive manner

Shape-dependence of near-field heat transfer between a spheroidal nanoparticle and a flat surface

We study the radiative heat transfer between a spheroidal metallic nanoparticle and a planar metallic sample for near- and far-field distances. In particular, we investigate the shape dependence of the heat transfer in the near-field regime. In comparison with spherical particles, the heat transfer typically varies by factors between 1/2 and 2 when the particle is deformed such that its volume is kept constant. These estimates help to quantify the deviation of the actual heat transfer recorded by a near-field scanning thermal microscope from the value provided by a dipole model which assumes a perfectly spherical sensor

Environmental changes and violent conflict

This letter reviews the scientific literature on whether and how environmental changes affect the risk of violent conflict. The available evidence from qualitative case studies indicates that environmental stress can contribute to violent conflict in some specific cases. Results from quantitative large-N studies, however, strongly suggest that we should be careful in drawing general conclusions. Those large-N studies that we regard as the most sophisticated ones obtain results that are not robust to alternative model specifications and, thus, have been debated. This suggests that environmental changes may, under specific circumstances, increase the risk of violent conflict, but not necessarily in a systematic way and unconditionally. Hence there is, to date, no scientific consensus on the impact of environmental changes on violent conflict. This letter also highlights the most important challenges for further research on the subject. One of the key issues is that the effects of environmental changes on violent conflict are likely to be contingent on a set of economic and political conditions that determine adaptation capacity. In the authors' view, the most important indirect effects are likely to lead from environmental changes via economic performance and migration to violent conflict. © 2012 IOP Publishing Ltd

Demand, supply, and restraint: Determinants of domestic water conflict and cooperation

This article focuses on one of the most likely empirical manifestations of the "environment-conflict" claim by examining how demand for and supply of water may lead to domestic water conflict. It also studies what factors may reduce the risk of conflict and, hence, induce cooperation. To this end, the article advances several theory-based arguments about the determinants of water conflict and cooperation, and then analyzes time-series cross-section data for 35 Mediterranean, Middle Eastern, and Sahel countries between 1997 and 2009. The empirical results show that demand-side drivers, such as population pressure, agricultural productivity, and economic development are likely to have a stronger impact on water conflict risk than supply-side factors, represented by climate variability. The analysis also reveals that violent water conflicts are extremely rare, and that factors conducive to restraint, such as stable political conditions, may stimulate cooperation. Overall, these results suggest that the joint analysis of demand, supply, and restraint improves our ability to account for domestic water-related conflict and cooperation