Kollegiale Reflexionen von Mathematiklehrkräften der Grundschule

Die vorliegende Forschungsarbeit beschäftigt sich mit der Entwicklung der Lehrerprofessionalisierung durch die kollegialen Reflexionen videodokumentierter Gesprächsausschnitte. Dazu wird ein Ausschnitt einer kollegialen Reflexion mit dem dazu entwickelten theoretischen Analyseinstrument untersucht

Learning Conditional Lexicographic Preference Trees

We introduce a generalization of lexicographic orders and argue that this generalization constitutes an interesting model class for preference learning in general and ranking in particular. We propose a learning algorithm for inducing a so-called conditional lexicographic preference tree from a given set of training data in the form of pairwise comparisons between objects. Experimentally, we validate our algorithm in the setting of multipartite ranking

Nutrient-Induced Modifications of Wood Anatomical Traits of Alchornea lojaensis (Euphorbiaceae)

Regarding woody plant responses on higher atmospheric inputs of the macronutrients nitrogen (N) and phosphorous (P) on tropical forests in the future, an adaptive modification of wood anatomical traits on the cellular level of woody plants is expected. As part of an interdisciplinary nutrient manipulation experiment (NUMEX) carried out in Southern Ecuador, we present here the first descriptive and quantitative wood anatomical analysis of the tropical evergreen tree species Alchornea lojaensis (Euphorbiaceae). We sampled branch wood of nine individual trees belonging to treatments with N fertilization, N+P fertilization, and a control group, respectively. Quantitative evaluations of eleven different vessel parameters were conducted. The results showed that this endemic tree species will be able to adapt well to the future effects of climate change and higher nutrient deposition. This was firstly implied by an increase in vessel diameter and consequently a higher theo. area-specific hydraulic conductivity with higher nutrient availability. Secondly, the percentage of small vessels (0–20 μm diameter) strongly increased with fertilization. Thirdly, the vessel arrangement (solitary vessels vs. multiple vessel groupings) changed toward a lower percentage of solitary vessel fraction (VS), and concurrently toward a higher total vessel grouping index (VG) and a higher mean group size of non-solitary vessels (VM) after N and N+P addition. We conclude that higher nutrient availability of N and N+P triggered higher foliage amount and water demand, leading to higher cavitation risk in larger vessels. This is counteracted by a stronger grouping of vessels with smaller risk of cavitation to ensure water supply during drier periods that are expected to occur in higher frequency in the near future

Determinants of farmers' tree-planting investment decisions as a degraded landscape management strategy in the central highlands of Ethiopia

Land degradation due to lack of sustainable land management practices is one of the critical challenges in many developing countries including Ethiopia. This study explored the major determinants of farm-level tree-planting decisions as a land management strategy in a typical farming and degraded landscape of the Modjo watershed, Ethiopia. The main data were generated from household surveys and analysed using descriptive statistics and a binary logistic regression model. The model significantly predicted farmers' tree-planting decisions (χ2 =  37.29, df  =  15, P < 0.001). Besides, the computed significant value of the model revealed that all the considered predictor variables jointly influenced the farmers' decisions to plant trees as a land management strategy. The findings of the study demonstrated that the adoption of tree-growing decisions by local land users was a function of a wide range of biophysical, institutional, socioeconomic and household-level factors. In this regard, the likelihood of household size, productive labour force availability, the disparity of schooling age, level of perception of the process of deforestation and the current land tenure system had a critical influence on tree-growing investment decisions in the study watershed. Eventually, the processes of land-use conversion and land degradation were serious, which in turn have had adverse effects on agricultural productivity, local food security and poverty trap nexus. Hence, the study recommended that devising and implementing sustainable land management policy options would enhance ecological restoration and livelihood sustainability in the study watershed

Why does accuracy assessment and validation of multi-resolution-based satellite image classification matter? A methodological discourse

This study presents a methodological discourse about how to validate the reliability of thematic maps derived from multi-resolution satellite-based image classification. Besides, the paper examines unbiased estimates of accuracy assessment using known sampling units. Landsat and spot images were used for lulc thematic layer extraction. These thematic layers together with reference data extracted from panchromatic aerial photo interpretation and ground survey were used as input datasets for accuracy assessment and validation analysis. For each lulc unit, a minimum of 50 reference samples were derived using a stratified random sampling scheme. Consequently, error matrices were generated to validate the quality of the 1973, 1995 and 2007 lulc maps. To improve sampling biases introduced due to the stratified random sampling reference data collection scheme, accuracy assessment indices including the producer’s, user’s and overall accuracy as well as Kappa coefficient of agreement were adjusted to the known areal proportion of map categories. The computed overall accuracy, corrected for bias using known marginal proportions of the 1973, 1995 and 2007 thematic layers were 88.12%, 89.95% and 92.27%, respectively. Also, 81.20%, 82.17% and 83.11% of Kappa coefficient of agreement were achieved from the 1972, 1995 and 2007 classifications, respectively. The findings show that high resolution aerial photos are good sources of  reference datasets in the absence of historical ground truth data for accuracy assessment analysis and the lulc classifications fulfilled the minimum of lulc classification standards of overall accuracy and Kappa coefficient of agreement. Consequently, all the lulc classifications could be used as an input for policy options for integrated land resource management practices in the watershed studied

Enhancing the energy resolution of resonant coherent excitation using the cooled U 89+ beam extracted from the ESR

Synopsis We report on the resonant coherent excitation (RCE) of the 2 s -2 p 3/2 transition in Li-like U 89+ with an enhanced energy resolution, which was achieved by reducing the projectiles momentum spread. The kinetic temperature of the beam was decreased by electron cooling in the ESR, and the collisional momentum broadening in the target was suppressed by the use of thin crystal (1.0 and 2.5 μm-thick). The resonance width was observed to be ∼1.4 eV in FWHM, which is three-times narrower than that from the previous work

A dynamic network model of the unsecured interbank lending market

We introduce a dynamic network model of interbank lending and estimate the parameters by indirect inference using network statistics of the Dutch interbank market from February 2008 to April 2011. We find that credit-risk uncertainty and peer monitoring are significant factors in explaining the sparse core-periphery structure of the market and the presence of relationship lending. Shocks to credit-risk uncertainty lead to extended periods of low market activity, intensified by reduced peer monitoring. Moreover, changes in the central bank's interest rate corridor have both a direct effect on the market as well as an indirect effect by changing banks’ monitoring efforts

Ladungsändernde Stöße mit Ionen und Photonen : von Atomen zu Molekülen

Diese Arbeit beschäftigt sich mit den elementaren Prozessen des Ladungstransfers und der Ionisation bei der Wechselwirkung von Atomen und Molekülen mit Ionen und Photonen. Die technologische Entwicklung der letzten zwei Jahrzehnte sowohl im Bereich der Beschleuniger als auch im Bereich der experimentellen Methoden erlauben heutzutage eine sehr detaillierte Untersuchung dieser Prozesse bis hin zu kinematisch vollständigen Experimenten nicht nur an Atomen, sondern auch an Molekülen. Die Untersuchung der Photodoppelionisation an Zweielektronensystemen ist besonders geeignet, die Elektron-Elektron-Wechselwirkung zu studieren. Nahe der Doppelionisationschwelle erlaubt die Wannier-Theorie eine qualitativ gute Beschreibung der Endzustandsverteilung. Dabei bietet es sich an, statt der Bewegung zweier Elektronen im Feld des He-Kernes die Bewegung des Kernes auf dem Sattel zwischen den Potentialen der sich entfernenden Elektronen zu betrachten. Die Messungen zeigen, daß diese Wannier-Beschreibung auch noch bei Photonenenergien von 20 eV über der Schwelle anwendbar ist. Auch mit convergent close-coupling Rechnungen wurde eine gute Übereinstimmung erzielt.Das molekulare Analogon zu Helium ist das Deuterium-Molekül. Hier zeigt sich ein deutlicher Einfluss der Molekülachse auf die Emissionscharakteristik der Elektronen, der auch erhalten bleibt, wenn über den Impuls eines der beiden Elektronen und alle möglichen Orientierungen der Molekülachse integriert wird. Experimente mit Ion-Ion-Stößen erlauben Untersuchungen an maßgeschneiderten Stoßsystemen. So können nur in Ion-Ion-Stößen reine Einelektronensysteme bei unterschiedlichsten Kernladungen untersucht werden und auch nur im Ion-Ion-Stoß ist es möglich, den Ladungstransfer in einem reinen Einelektronensystem mit einem Molekül zu untersuchen. Dies wird am Stoß eines Heliumkernes mit einem Wasserstoffmolekülion diskutiert. Ferner wurden auch Stöße zwischen zwei Fulleren-Ionen erstmals in dieser Arbeit untersucht. Fullerene können als das Bindeglied zwischen einfachen Molekülen wie Wasserstoff und komplexen Systemen bzw. Festkörpern angesehen werden. Basierend auf einem Modell frei beweglicher Löcher auf einer unendlich gut leitenden Kugel entwickelten Presnyakov et al. eine quantenmechanische Behandlung, welche die experimentellen Ergebnisse sehr gut beschreibt. Es besteht aber auch ein anwendungsbezogenes Interessean Wirkungsquerschnitten für ladungsändernde Stöße bei schweren Ionen wie z.B. Blei oder Uran zur Abschätzung von Teilchenverlusten in zukünftigen Teilchenbeschleunigern und Speicherringen. Hier ist man auf experimentelle Daten angewiesen. Die Messungen zeigen, dass für Ladungszustände bis q=4+ bei den für die Zukunft geplanten Strahlintensitäten die Verluste durch ladungsändernde Stöße nicht vernachlässigbar sind. Auch dieIonisation spielt im Vergleich zum Ladungstransfer bei einigen Systemen eine entscheidende Rolle