Natriuretic peptide receptors on rat thymocytes: Inhibition of proliferation by atrial natriuretic peptide.

Because the thymus expresses the natriuretic peptides (NP) as well as their respective receptors, an involvement of NP in the physiology of this organ has been suggested. To evaluate functional aspects of NP in the thymus, we looked for thymic cells bearing NP receptors (Npr). Furthermore, the regulation of Npr expression by activation of cells and the influence of NP on the proliferation of thymocytes was studied. Expression of receptor messenger RNAs CmRNAs) was examined by PCR and Northern blot. Existence of functional Npr was confirmed by measurement of cGMP, the second messenger of NP. Proliferation of thymocytes upon concanavalin A (Con A) stimulation was analyzed by incorporation of [“Hlthymidine. We report here that thymocytes express mRNAs for the three Npr, namely Npra, Nprb, and Nprc and that activation of Npra and Nprb increases cGMP levels. Stimulation of thymocytes with Con A (1 pg/ml, 48 h) resulted in an increase of mRNA coding for Npra, the receptor specific for atria1 natriuretic peptide (ANP) and brain natriuretic peptide. Nprb and Nprc receptor expression was not altered under these conditions. In agreement with these data only ANP, but not the C-type natriuretic peptide, elicited increased cGMP response in Con A-stimulated cells. ANP inhibited also the proliferation of Con A stimulated thymocytes, whereas C-type natriuretic peptide did not show this effect. These results suggest that ANP affects the complex mechanisms of thymocyte proliferation and differentiation

Neural mechanisms of social cognition – the mirror neuron system and beyond

In my PhD thesis, I present three functional magnetic resonance imaging studies aimed at investigating neurobiological mechanisms underlying social cognition. My thesis focuses on fast and automatic processes that are proposed to build the basis of social understanding, and might be activated in parallel to more effortful deliberate mechanisms. The proposed neural substrate of fast and automatic processes are mirror neurons, which according to the theory of embodied simulation allow humans to understand other individuals’ actions, and even emotions and intentions. Since non-invasive techniques cannot be applied to measure mirror neurons, but only neural populations assumed to constitute the mirror neuron system, experimental paradigms and analysis routines that allow approximation of mirror neuron functions need to be developed. In study 1, I demonstrated that different social cognitive skills, including imitation, affective empathy and theory of mind share a common neural basis, located in regions associated with the mirror neuron system. In addition to standard analyses, a shared voxel analysis was applied that revealed common activation for social-cognitive processes not only across, but also within participants. Study 2 was set up to investigate whether the mirror neuron system can distinguish the valence of facial configurations. The use of a functional magnetic resonance imaging adaptation paradigm allowed to determine neural populations sensitive to emotional valence. While the fusiform gyrus was sensitive to changes from fearful to smiling faces and also from smiling to fearful faces, Brodmann area 44 reaching into insula, and superior temporal sulcus, i.e. regions more commonly associated with the mirror neuron system and with the so called mentalizing network, showed particularly increased activation for switches from smiling to fearful faces. Study 3 was dedicated to the investigation of decision making in the context of ambiguous facial configurations. While probabilistic decision making on these facial configurations lead to activation in the executive control network, final decisions for an emotion resulted in nucleus accumbens activation. In addition, perceiving fear in a face lead to higher nucleus accumbens activation during final decisions than perceiving happiness. This finding can be linked to salience processing in the nucleus accumbens. In conclusion, all three studies show an involvement of fast and automatic processing regions for different social-cognitive processes. Study 3 additionally examined the interaction with slower and more deliberate processes, as involved in probabilistic decision making on ambiguous faces. The mirror neuron system seems to be critically involved in different social-cognitive tasks and also sensitive to emotional valence. In cases when automatic processing is not possible, as when presented with ambiguous facial configurations, brain regions commonly associated with probabilistic decision making assist, and the nucleus accumbens, possibly by directing salience, is involved in the final decision. These results deepen the understanding of the mechanisms of social cognition and encourage the use of sophisticated methods in experimental paradigms and analysis

Unitarisation of EFT Amplitudes for Dark Matter Searches at the LHC

We propose a new approach to the LHC dark matter search analysis within the effective field theory (EFT) framework by utilising the K-matrix unitarisation formalism. This approach provides a reasonable estimate of the dark matter production cross section at high energies, and hence allows reliable bounds to be placed on the cut-off scale of relevant operators without running into the problem of perturbative unitarity violation. We exemplify this procedure for the effective operator D5 in monojet dark matter searches in the collinear approximation. We compare our bounds to those obtained using the truncation method and identify a parameter region where the unitarisation prescription leads to more stringent bounds.Comment: 20 pages, 7 figures. References added and minor corrections made to match published versio

Correction of Bathymetric Survey Artifacts Resulting from Apparent Wave-Induced Vertical Position of an AUV

Recent increases in the capability and reliability of autonomous underwater vehicles (AUVs) have provided the opportunity to conduct bathymetric seafloor surveys in shallow water (\u3c 50 m). Unfortunately, surveys of this water depth may contain artifacts induced by large amplitude wave motion at the surface. The artifacts occur when an onboard pressure sensor determines the depth of the AUV. Waves overhead induce small pressure fluctuations at depth, which modulate the AUV’s pressure sensor output without causing actual vertical movement of the AUV. Since bathymetric measurements are made with respect to the AUV’s depth, these pressure fluctuations, in turn, modulate the measurement of the seafloor. The result is a periodic across-track, vertical offset of the seafloor profile (similar to a heave artifact sometimes common in surface vessel surveys). In this paper we describe our experience with the “Gavia” model AUV (Hafmynd EHF, Iceland) in a recent bathymetric survey during which wave action overhead induced such an artifact with a peak-to-peak amplitude as large as 1 meter. A method for removing the artifact as well as recommendations for modifications to the sonar, INS and AUV to mitigate the effect in the future are provided

Obstacles to the diffusion of adaptation in the Rhein-Neckar region in Germany

Because the impacts of climate change are felt at the local level, we assess adaptation diffusion mechanisms (i.e., learning, competition, and emulation) among smaller big cities and medium-sized towns. Since the diffusion of adaptation has immediate spatial implications, we argue that local conditions play an important role in the diffusion process. The densely populated Rhein-Neckar Metropolitan Region in Germany is an ideal case for studying diffusion mechanisms with regard to adaptation. Using a rich data set of 28 interviews, we unpack the views of local actors such as mayors, city council politicians, city administration representatives, and representatives from regional agencies and identify factors influencing the diffusion of adaptation. We find limited or compromised diffusion due to insufficient knowledge about adaptation, competition between municipalities, and cooperation with cities outside the region. In addition, we find some (albeit limited) political will for adaptation. While some of the interviewed politicians considered making long-term investments in adaptation, most highlighted competing local issues and viewed adaptation with caution, illustrating adaptation’s lack of salience and social legitimacy. Indeed, one crucial finding was that housing and mobility are more important to a wide range of politicians and bureaucrats alike. By examining diffusion mechanisms at the subnational level, we combine theoretical perspectives from political science and geography to show how local decision-makers—in particular, politicians—influence the diffusion mechanisms of adaptation

Neue Packungsmaterialien für die Anionenchromatographie - Synthese und Anwendungsmöglichkeiten

Die Fragestellungen in der Ionenchromatographie werden immer spezieller. Dabei ist es schwierig, aus dem kommerziell erhältlichen Programm die passende Trennsäule samt Eluenten zu finden. Deshalb wurden sich im Grundpolymer, im Spacer und im Amin unterscheidende Anionenaustauscher getestet und miteinander verglichen. Daraus ergibt sich ein umfangreiches Wissen über das Verhalten dieser verschiedenen Arten von Trennsäulen und ein einzigartiger Pool an Anionenaustauschern, aus denen je nach Art des Trennproblems die passende Säule samt angepaßten Eluenten ausgesucht werden kann. Ausgenutzt wurde dies zur Bestimmung anionischer Verunreinigungen in hochreiner, konzentrierter Salpetersäure, wie sie in der Halbleitertechnik benutzt wird. Dazu wurden zwei IC-Systeme über ein externes 6-Port-Ventil und eine Konzentratorsäule miteinander gekoppelt. Im ersten Teil zeigten die Analytanionen Chlorid, Sulfat und Phosphat mit einem speziellen, hochkapazitiven Anionenaustauscher in Kombination mit einem hochkonzentrierten Natronlauge-Eluenten sehr viel kürzere Retentionszeiten als die Matrix Nitrat und konnten so von dieser getrennt werden. Im zweiten Schritt wurden sie dann mit Hilfe eines kommerziellen Anionenaustauschers quantifiziert

Warum Klimakonferenzen scheitern, aber dennoch zum Wohl des Weltklimas kooperiert wird

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