Modeling the Impact of Climate and Vegetation on Fire Regimes in Mountain Landscapes

Assessing the long-term dynamics of mountain landscapes that are influenced by large-scale natural and anthropogenic disturbances and a changing climate is a complex subject. In this study, a landscape-level ecological model was modified to this end. We describe the structure and evaluation of the fire sub-model of the new landscape model LandClim, which was designed to simulate climate-fire-vegetation dynamics. We applied the model to an extended elevational gradient in the Colorado Front Range to test its ability to simulate vegetation composition and the strongly varying fire regime along the gradient. The simulated sequence of forest types along the gradient corresponded to the one observed, and the location of ecotones lay within the range of observed values. The model captured the range of observed fire rotations and reproduced realistic fire size distributions. Although the results are subject to considerable uncertainty, we conclude that LandClim can be used to explore the relative differences of fire regimes between strongly different climatic condition

A C. elegans model for neurodegeneration in Cockayne syndrome.

Cockayne syndrome (CS) is a congenital syndrome characterized by growth and mental retardation, and premature ageing. The complexity of CS and mammalian models warrants simpler metazoan models that display CS-like phenotypes that could be studied in the context of a live organism. Here, we provide a characterization of neuronal and mitochondrial aberrations caused by a mutation in the csb-1 gene in Caenorhabditis elegans. We report a progressive neurodegeneration in adult animals that is enhanced upon UV-induced DNA damage. The csb-1 mutants show dysfunctional hyperfused mitochondria that degrade upon DNA damage, resulting in diminished respiratory activity. Our data support the role of endogenous DNA damage as a driving factor of CS-related neuropathology and underline the role of mitochondrial dysfunction in the disease

Accurate tuning of ordered nanotubular platinum electrodes by galvanic plating

Platinum nanotubes are created by galvanic deposition inside porous templates. The effects of the electrolyte's ion concentration and pH, of the applied potential and of the deposition duration on the morphology of the tubes are investigated systematically. The system provides a model electrode platform with accurately tunable geometry for the fundamental investigation of electrochemical transformations. For slow electrochemical reactions, we observe a linear increase of the galvanic current with the length of the nanotubes, and therefore with the specific surface area of the electrode. In contrast to this, inherently fast electrochemical transformations are diffusion-limited and give rise to the same current density independently of the geometry. These results delineate a strategy for optimizing the performance of electrochemical energy conversion devices systematically via nanostructuring the electrode surfaces

Improved Biocompatibility of Amino‐Functionalized Graphene Oxide in Caenorhabditis elegans

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The tumor suppressor CYLD regulates the p53 DNA damage response

The tumour suppressor CYLD is a deubiquitinase previously shown to inhibit NF-κB, MAP kinase and Wnt signalling. However, the tumour suppressing mechanisms of CYLD remain poorly understood. Here we show that loss of CYLD catalytic activity causes impaired DNA damage-induced p53 stabilization and activation in epithelial cells and sensitizes mice to chemical carcinogen-induced intestinal and skin tumorigenesis. Mechanistically, CYLD interacts with and deubiquitinates p53 facilitating its stabilization in response to genotoxic stress. Ubiquitin chain-restriction analysis provides evidence that CYLD removes K48 ubiquitin chains from p53 indirectly by cleaving K63 linkages, suggesting that p53 is decorated with complex K48/K63 chains. Moreover, CYLD deficiency also diminishes CEP-1/p53-dependent DNA damage-induced germ cell apoptosis in the nematode Caenorhabditis elegans. Collectively, our results identify CYLD as a deubiquitinase facilitating DNA damage-induced p53 activation and suggest that regulation of p53 responses to genotoxic stress contributes to the tumour suppressor function of CYLD

The Great Slump : Mrk 926 reveals discrete and varying Balmer line satellite components during a drastic phase of decline

This work has been supported by the DFG grants KO857/35-1 and CH71/34-3. K. H. acknowledges support from STFC grant ST/M001296/1. D. C. acknowledges support from ISF grant 2398/19.Aims. Mrk 926 is known to be a highly variable active galactic nucleus. Furthermore, it is known to show very broad line profiles. We intended to study the continuum and line profile variations of this object with high temporal resolution in order to determine its broad-line region structure and to derive its black hole mass. Methods. We carried out a high-cadence spectroscopic variability campaign of Mrk 926 with the 10m HET telescope, aided by photometric V-band data taken with the C18 telescope at the Wise Observatory, over a period of about five months. We extracted spectroscopic continuum and line light curves, and computed cross-correlation functions (CCFs) as well as velocity-resolved CCFs with respect to the combined spectroscopic and photometric V-band light curve. Results. The continuum luminosity of Mrk 926 showed a drastic decrease during our campaign. The luminosity dropped to less than 50% of its original luminosity within only 2.5 months. Furthermore, the spectra of Mrk 926 show complex and very broad Balmer line profiles, including outer Balmer satellites ranging from ±5000 to ±13 000 km s−1. The integrated Hα, Hβ, and He Iλ5876 line light curves are delayed relative to the continuum light curve. The Hα and Hβ lines show two velocity-delay structures in the central part of their line profile (within ±5000 km s−1), at ∼10 and ∼57 light-days and at ∼5 and ∼48 light-days, respectively. These structures might be interpreted as the upper and lower halves of an ellipse in the velocity-delay plane, which might be the signature of a line-emitting ring, inclined by ∼50° to the line of sight and orbiting the black hole at radii, R, of 33.5 and 26.5 light-days. We determined continuum luminosities, log(λ Lλ/erg s−1), of 43.68–44.13, which are in good agreement with the established RBLR − LAGN relation. Adopting delays of 33.5 and 26.5 days for Hα and Hβ, respectively, we derive a black hole mass of (1.1 ± 0.2)×108 M⊙; this indicates a low Eddington ratio, which decreased from 8 to 3 percent during our campaign. The Balmer satellite components show a higher correlation coefficient with respect to the continuum than the central line profile, and their response to the continuum variations is on the order of only 3 − 5 days. We attribute this to the central line segment and the Balmer satellites having different, spatially distinct regions of origin.Publisher PDFPeer reviewe

Teaching Tips – Gute Lehre ist kein Glücksfall!

Fragen wir die Teilnehmerinnen und Teilnehmer unserer hochschuldidaktischen Weiterbildungen nach ihren Erwartungen, so nennen sie an erster Stelle immer „konkrete Hilfestellungen für den Lehralltag“. Schauen wir genauer hin, wie diese Hilfestellungen aussehen könnten, so zeigen sich deutliche Unterschiede in den Zielgruppen der Lehrenden. Stehen sie noch am Anfang ihrer Lehrkarriere, wünschen sie sich besonders Hilfestellungen, die den Einstieg in die Lehre erleichtern bzw. ihnen helfen, effektiv zu lehren und effiziente Lehrende zu werden. Für erfahrene Lehrende hingegen, die zudem mit Prüfungen betraut sind, stellt sich darüber hinaus oft die Frage nach der Auswahl von Prüfungsformen und die Bewertung von Prüfungsleistungen, vor allem da ihnen die Modulabschlussprüfungen eine größere Bandbreite an Formen alternativer Leistungsbewertung eröffnen. Beiden Zielgruppen gemein ist die Suche nach praktischer Hilfe bei der Professionalisierung ihres didaktischen Handelns. Mit Patentrezepten ist ihnen dabei nicht gedient. Das Interesse der Lehrenden an Methoden wird gleichwohl als ein legitimes Interesse gesehen, denn Methodenwissen spielt bei der Vermittlung von Wissen eine große Rolle. Besonders im Kontext von Medialisierung werden die Vermittlungsmethoden wichtiger. Die hochschuldidaktische Weiterbildung will den Lehrenden bei der Entwicklung ihres individuellen und professionellen Lehrprofils theoretisch begründet, serviceorientiert zur Seite stehen. Seit Mitte der 1990er Jahre ist die didaktische Ausbildung für die Lehre nicht mehr dem Zufall überlassen, ebenso wie es keine Notwendigkeit mehr ist, sich hochschuldidaktisches Wissen autodidaktisch anzueignen. Die Entwicklung der Hochschuldidaktik und damit einhergehend die Entwicklung von curriculumbasierten, modularisierten und systematisch aufgebauten Weiterbildungsprogrammen hat in den letzten Jahrzehnten nicht zuletzt dank verschiedener Programme und Initiativen (z.B. Länderprogramme „Qualität der Lehre“, „Exzellenzinitiative“, BMBF, Stifterverband) eine enorme Steigerung erfahren. Die Qualität der Lehre an Universitäten ist zu einem Wettbewerbsfaktor unter den Universitäten geworden und kann zu ihrer Profilbildung beitragen. Die Lehrkompetenz kann als Schlüssel für die Qualität der Lehre gesehen werden und ist ein Merkmal akademischer Personalentwicklung. Dieses Journal soll in kleinem Rahmen als praxisorientierter Ratgeber auftreten. Es soll darüber hinaus das Interesse an hochschuldidaktischer Weiterbildung wecken, Lust machen, sich mit der eigenen Lehre auseinanderzusetzen, sich den kollegialen Fragen der anderen Teilnehmer/inne/n in den Workshops zu stellen, gemeinsam mit ihnen und uns, den Hochschuldidaktikern und Hochschuldidaktikerinnen, mögliche Antworten aufzuspüren und so das eigene Lehrrepertoire zu erweitern

Activated fibronectin-secretory phenotype of mesenchymal stromal cells in pre-fibrotic myeloproliferative neoplasms

We characterized bone marrow stromal cells (BMSC) from patients with pre-fibrotic myeloproliferative neoplasms (MPN). MPN-BMSC showed decreased capacity to stimulate the proliferation of colony-forming units of normal hematopoietic stem and progenitor cells and displayed increased matrix remodelling (in particular fibronectin deposition) compared to control BMSC. This finding was confirmed in pre-fibrotic MPN bone marrow biopsies in a tissue microarray (n = 34), which stained positive for fibronectin in the absence of reticulin as a standard myelofibrosis marker. Fibronectin expression correlated significantly with reduced haemoglobin levels in MPN-patients (p = 0.007; R2 = 0.42). Our data show significant cell-intrinsic alterations in MPN-MSC and suggest that Fibronectin expression might be applicable as a biomarker for the identification of early myelofibrotic transformation in reticulin-negative MPN