Learning from errors: effects of teachers training on studentsâ attitudes towards and their individual use of errors

Constructive error handling is considered an important factor for individual learning processes. In a quasi-experimental study with Grades 6 to 9 students, we investigate effects on students’ attitudes towards errors as learning opportunities in two conditions: an error-tolerant classroom culture, and the first condition along with additional teaching of strategies for analyzing errors. Our findings show positive effects of the error-tolerant classroom culture on the affective level, whereas students are not influenced by the cognitive support. There is no evidence for differential effects for student groups with different attitudes towards errors

Characterisation of Anti-Apoptotic Signalling Pathways in Hepatocytes activated by alpha-Lipoic Acid and Atrial Natriuretic Peptide

Both, the R-enantiomer of the antioxidant alpha-lipoic acid (R-LA) and the hormone atrial natriuretic peptide (ANP) are known to exert potent hepatoprotective action. The present work characterises alpha-lipoic acid- and ANP-mediated signal transduction pathways involved in the regulation of apoptotic cell death in two different models: primary hepatocytes and ischemic isolated perfused rat livers. alpha-lipoic acid was shown to protect isolated hepatocytes from TNF-alpha-/ActinomycinD-induced apoptosis. Astonishingly, this effect did not seem to be governed neither by its well described antioxidative nor its Fe-chelating properties. In fact, the LA-mediated activation of the PI3-K/Akt survival pathway seemed to be responsible for the antiapoptotic properties of alpha-lipoic acid. Consequently, incubation with a specific PI3-K-inhibitor significantly reduced both, R-LA-mediated decrease in caspase activity and R-LA-induced BAD phosphorylation. Thus, PI3-K-mediated Akt activation and subsequent phosphorylation of the proapoptotic protein BAD at Ser136 are causally involved in the antiapoptotic signalling mediated by R-LA. Perfusion with ANP 20 min prior to the ischemic period is known to reduce apoptotic cell death occurring at the end of the ischemic period. We could previously show that this preconditioning of rat livers leads to a marked activation of p38 MAPK. Since ANP reduces apoptotic cell death, the potential connection between this ANP-induced p38 MAPK activation and apoptosis reduction was investigated. Astonishingly, liver perfusion with an p38 MAPK inhibitor even decreased apoptotic cell death, supporting a detrimental role of this kinase. PKA-specific inhibitors demonstrated the involvement of PKA in this ANP-mediated protection. Interestingly, it also turned out that PKA phosphorylates the proapoptotic protein BAD at Ser112, an effect known to contribute to the inhibition of apoptosis. In summary, the present data show for the first time that phosphorylation of BAD at either Ser136 or Ser112 turns out to be a central protective mechanism to defend from hepatocyte apoptosis

Occurrence and spatial pattern of water repellency in a beech forest subsoil

Most recent studies on soil water repellency (WR) were limited to the humous topsoil or to shallow subsoil layers slightly below the main root zone to approximately 0.5 m depth. Hence, the main objective of the present study was to investigate the wettability pattern of a forest soil including the deeper subsoil. The selected site was a 100 years old beech forest on a well-drained sandy Cambisol in northern Germany which showed moderate to partly extended acidification. Results obtained from three sampling transects (3 m length, 2 m depth; sampling grid 8 × 8 samples per transect; minimum distance of sampling locations to nearest tree about 0.5 m) show that contact angles (CA) were always in the subcritical WR range (0° < CA < 90°). Significant impact of the tree distance on WR was not observed for any of the transects. A prominent feature of two transects was the minimum WR level (CA < 10°) for samples with soil organic carbon (SOC) contents around 0.25–0.4%. For the topsoils it was observed that CA increased with SOC content from that minimum to a maximum CA of 60–75° for transects 1 and 2 with mean pH values < 3.5. For transect 3 with slightly higher average pH close to 4.0, average CA of samples were always < 10° and showed no trend to increase with increasing SOC content or other soil parameters like N content or C/N ratio. Subsoil samples, however, behave differently with respect to SOC: for these samples, generally low in SOC, the CA increase with decreasing SOC occurred at all transects for approximately 50% of the samples but did not show any clear tendencies with respect to further parameters like texture, pH or N content. We conclude that the SOC content is the most prominent parameter determining wettability, either positively correlated with WR for topsoils or negatively correlated for subsoil samples very low in SOC. We finally conclude for moderately acid beech forest stands that emerging WR starts in the A horizon after reaching a pH lower than 3.5, whereas subsoil WR might appear already at higher pH values. Even SOC contents of ~0.01–0.02% turned out to be very effective in increasing the CA up to 70°, which points out clearly the importance of small amounts of soil organic matter in affecting subsoil wettability. With respect to site hydrology we conclude that ongoing acidification as well as predicted higher frequencies of extended droughts due to climate change will promote the occurrence of WR with corresponding implications for site and catchment hydrology.DFG/BA 1359/13-1DFG/BA 1359/14-

The ocean carbon sink – impacts, vulnerabilities and challenges

Carbon dioxide (CO2) is, next to water vapour, considered to be the most important natural greenhouse gas on Earth. Rapidly rising atmospheric CO2 concentrations caused by human actions such as fossil fuel burning, land-use change or cement production over the past 250 years have given cause for concern that changes in Earth’s climate system may progress at a much faster pace and larger extent than during the past 20 000 years. Investigating global carbon cycle pathways and finding suitable adaptation and mitigation strategies has, therefore, become of major concern in many research fields. The oceans have a key role in regulating atmospheric CO2 concentrations and currently take up about 25% of annual anthropogenic carbon emissions to the atmosphere. Questions that yet need to be answered are what the carbon uptake kinetics of the oceans will be in the future and how the increase in oceanic carbon inventory will affect its ecosystems and their services. This requires comprehensive investigations, including high-quality ocean carbon measurements on different spatial and temporal scales, the management of data in sophisticated databases, the application of Earth system models to provide future projections for given emission scenarios as well as a global synthesis and outreach to policy makers. In this paper, the current understanding of the ocean as an important carbon sink is reviewed with respect to these topics. Emphasis is placed on the complex interplay of different physical, chemical and biological processes that yield both positive and negative air–sea flux values for natural and anthropogenic CO2 as well as on increased CO2 (uptake) as the regulating force of the radiative warming of the atmosphere and the gradual acidification of the oceans. Major future ocean carbon challenges in the fields of ocean observations, modelling and process research as well as the relevance of other biogeochemical cycles and greenhouse gases are discussed

Prolonging somatic cell proliferation through constitutive hox gene expression in C. elegans

hox genes encode a conserved family of homeodomain transcription factors that are essential to determine the identity of body segments during embryogenesis and maintain adult somatic stem cells competent to regenerate organs. In contrast to higher organisms, somatic cells in C. elegans irreversibly exit the cell cycle after completing their cell lineage and the adult soma cannot regenerate. Here, we show that hox gene expression levels in C. elegans determine the temporal competence of somatic cells to proliferate. Down-regulation of the central hox gene lin-39 in dividing vulval cells results in their premature cell cycle exit, whereas constitutive lin-39 expression causes precocious Pn.p cell and sex myoblast divisions and prolongs the proliferative phase of the vulval cells past their normal point of arrest. Furthermore, ectopic expression of hox genes in the quiescent anchor cell re-activates the cell cycle and induces proliferation until young adulthood. Thus, constitutive expression of a single hox transcription factor is sufficient to prolong somatic cell proliferation beyond the restriction imposed by the cell lineage. The down-regulation of hox gene expression in most somatic cells at the end of larval development may be one cause for the absence of cell proliferation in adult C. elegans

Push-Pull Design of Bis(tridentate) Ruthenium(II) Polypyridine Chromophores as Deep Red Light Emitters in Light-Emitting Electrochemical Cells

Breivogel A, Park M, Lee D, et al. Push-Pull Design of Bis(tridentate) Ruthenium(II) Polypyridine Chromophores as Deep Red Light Emitters in Light-Emitting Electrochemical Cells. European Journal of Organic Chemistry. 2014;2014(2):288-295.Light-emitting electrochemical cells (LECs) with a simple device structure were prepared by using heteroleptic bis(tridentate) ruthenium(II) complexes [1](PF6)(2)-[3](PF6)(2) as emitters. The push-pull substitution shifts the emission energy to low energy, into the NIR region. The devices emit deep red light up to a maximum emission wavelength of 755 nm [CIE (International Commission on Illumination) coordinates: x = 0.731, y = 0.269 for [3](PF6)(2)], which, to the best of our knowledge, is the lowest emission energy for LECs containing bis(tridentate) ruthenium(II) complexes. A device structure of ITO/PEDOT:PSS/ruthenium(II) complex/Ag was used, and the thickness of the emitting layer was measured by AFM [ITO: indium tin oxide, PEDOT: poly(3,4-ethylenedioxythiophene), PSS: poly(styrenesulfonate), AFM: atomic force microscopy]. To enhance the external quantum efficiency (EQE), cells were fabricated with and without poly(methyl methacrylate) (PMMA) as additive in the emitting layer