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Mobbing an Schulen
(2016)
Das Buch beginnt mit einem ausführlichen Einblick in die Mobbing-Forschung, u. a. zu Merkmalen und Erscheinungsformen von Mobbing. Darüber hinaus werden Ursachen und Folgen von Mobbing, aber auch neue Formen wie das Cyber-Mobbing thematisiert. Im weiteren Verlauf stehen dann das Eingreifen bei und Vorbeugen von Mobbing im Mittelpunkt. Dabei werden etablierte Interventions- und Präventionsprogramme verständlich präsentiert, konkrete Empfehlungen gegeben, wie man in Mobbing-Situationen handeln kann, und Gelingensbedingungen beschrieben, wie es gar nicht erst zu Mobbing kommt. Gespickt mit vielen Fallbeispielen und einer ausführlichen Materialsammlung zum Download wird die Darstellung anschaulich und der praktische Transfer des präsentierten Wissens erleichtert.
The microstructure of permafrost ground contains clues to its formation and hence its preconditioning to future change.
We applied X-ray computed microtomography (CT) to obtain high-resolution data (Delta x = 50 mu m) of the composition of a 164 cm long permafrost core drilled in a Yedoma upland in north-eastern Siberia.
The CT analysis allowed the microstructures to be directly mapped and volumetric contents of excess ice, gas inclusions, and two distinct sediment types to be quantified. Using laboratory measurements of coarsely resolved core samples, we statistically estimated the composition of the sediment types and used it to indirectly quantify volumetric contents of pore ice, organic matter, and mineral material along the core.
We conclude that CT is a promising method for obtaining physical properties of permafrost cores which opens novel research potentials.
In contrast to molecular-dipole polymers, such as PVDF, ferroelectrets are a new class of flexible spatially heterogeneous piezoelectric polymers with dosed or open voids that act as deformable macro-dipoles after charging.
With a spectrum of manufacturing processes being developed to engineer the heterogeneous structures, ferroelectrets are made with attractive piezoelectric properties well-suited for applications, such as pressure sensors, acoustic transducers, etc.
However, the sources of the macro-dipole charges have usually been the same, microscopic dielectric barrier discharges within the voids, induced when the ferroelectrets are poled under a large electric field typically via a so-called corona poling, resulting in the separation and trapping of opposite charges into the interior walls of the voids.
Such a process is inherently self-limiting, as the reverse internal field from the macro-dipoles eventually extinguishes the microdischarges, resulting in limited density of ions and not too high overall piezoelectric performance. Here, a new method to form ferroelectrets with gigantic electroactivity is proposed and demonstrated with the aid of an external ion booster.
A laminate consisting of expanded polytetrafluoroethylene (ePTFE) and fluorinated-ethylene-propylene (FEP) was prefilled with bipolar ions produced externally by an ionizer and sequentially poled to force the separation of positive and negative ions into the open fibrous structure, rendering an impressive piezoelectric d(33)( )coefficient of 1600 pC/N-an improvement by a factor of 4 in comparison with the d(33) of a similar sandwich poled with nonenhanced corona poling.
The (pre)filling dearly increases the ion density in the open voids significantly. The charges stored in the open-cell structure stays at a high level for at least 4 months. In addition, an all-organic nanogenerator was made from an ePTFE-based ferroelectret, with conducting poly(3,4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) coated fabric electrodes.
When poled with this ion-boosting process, it yielded an output power twice that of a similar sample poled in a conventional corona-only process. The doubling in output power is mainly brought about by the significantly higher charge density achieved with the aid of external booster.
Furthermore, aside from the bipolar ions, extra monopolar ions can during the corona poling be blown into the open pores by using for instance a negative ionic hair dryer to produce a unipolar ePTFE-based ferroelectret with its d(33) coefficient enhanced by a factor of 3. Ion-boosting poling thus unleashes a new route to produce bipolar or unipolar open-cell ferroelectrets with highly enhanced piezoelectric response.
Hepatocytes secrete retinol-binding pro-tein 4 (RBP4) into circulation, thereby mobilizing vitamin A from the liver to provide retinol for extrahepatic tissues. Obesity and insulin resistance are associated with elevated RBP4 levels in the blood.
However, in a previous study, we observed that chronically increased RBP4 by forced Rbp4 expres-sion in the liver does not impair glucose homeostasis in mice.
Here, we investigated the effects of an acute mobilization of hepatic vitamin A stores by hepatic overexpression of RBP4 in mice.
We show that he-patic retinol mobilization decreases body fat content and enhances fat turnover. Mechanistically, we found that acute retinol mobilization increases hepatic expression and serum levels of fibroblast growth factor 21 (FGF21), which is regulated by retinol mobilization and retinoic acid in primary hepato-cytes.
Moreover, we provide evidence that the insulin-sensitizing effect of FGF21 is associated with organ-specific adaptations in retinoid homeostasis.
Taken together, our findings identify a novel cross-talk between retinoid homeostasis and FGF21 in mice with acute RBP4-mediated retinol mobilization from the liver.
For an effectively one-dimensional, semi-infinite disordered system connected to a reservoir of tracer particles kept at constant concentration, we provide the dynamics of the concentration profile.
Technically, we start with the Montroll-Weiss equation of a continuous time random walk with a scale-free waiting time density.
From this we pass to a formulation in terms of the fractional diffusion equation for the concentration profile C(x, t) in a semi-infinite space for the boundary condition C(0, t) = C-0, using a subordination approach.
From this we deduce the tracer flux and the so-called breakthrough curve (BTC) at a given distance from the tracer source.
In particular, BTCs are routinely measured in geophysical contexts but are also of interest in single-particle tracking experiments.
For the "residual' BTCs, given by 1- P(x, t), we demonstrate a long-time power-law behaviour that can be compared conveniently to experimental measurements.
For completeness we also derive expressions for the moments in this constant-concentration boundary condition.
Climate change, driven by increasing atmospheric levels of carbon dioxide (CO2), presents a significant societal challenge for the 21st century. Biotechnological approaches for microbial production of commodity chemicals and fuels offer possible solutions to re-fix CO2 from the atmosphere, thereby mitigating carbon emissions and contributing to a sustainable carbon-economy in the future. Biological CO2 fixation is also at the heart of agricultural productivity, where photosynthesis and the Calvin-Benson-Bassham cycle present promising biotechnological targets for crop improvement.
Synthetic biology allows testing metabolic solutions not known to exist in nature, which may exceed their natural counterparts in terms of efficiency. In this thesis, I explore the design of such new-to-nature metabolic pathways for biological CO2 utilization and their implementation in living cells (in vivo).
In the first chapter, I describe the development of a metabolic pathway that enables intracellular conversion of CO2 to formate, giving access to highly efficient carbon fixation routes. In nature, CO2-reduction remains restricted to anaerobic organisms and low redox potentials. Here, we introduce the “CORE cycle”, a synthetic metabolic pathway that converts CO2 to formate under fully aerobic conditions and ambient CO2 levels, using only NADPH as a reductant. We leverage this synthetic, ATP-energized pathway to overcome the thermodynamic and kinetic barriers associated with CO2-reduction. Applying rational metabolic engineering and adaptive evolution, this work demonstrates that Escherichia coli can utilize ambient CO2 as the sole source of one-carbon units and serine, achieving a first step towards novel modes of synthetic autotrophy. We further apply computational modeling to showcase the potential of the CORE cycle as a photorespiratory bypass for enhancing photosynthesis.
In the second chapter, I describe the development of the “LCM module”, a novel metabolic route for CO2-incorporating conversion of acetyl-CoA to pyruvate. This route relies on the newly uncovered, promiscuous activity of an adenosylcobalamin (B12)-dependent enzyme, which we significantly optimize through targeted hypermutation and in vivo selection strategies. The LCM module provides a shorter and more efficient pathway for acetyl-CoA assimilation compared to natural routes, offering novel opportunities for synthetic CO2 fixation.
Overall, through theoretical pathway analysis, enzyme bioprospecting, and modular metabolic engineering in E. coli, this thesis expands the solution space for biological CO2 fixation.
Optics is a core field in the curricula of secondary physics education. In this study, we present the development and validation of a test instrument in the field of optics, the ray optics in converging lenses concept inventory (ROC-CI). It was developed for and validated with middle school students, but can also be adapted for the use in higher levels of physics education.
The ROC-CI can be used as a formative or a summative assessment of students' conceptual understanding of image formation by converging lenses, assessing the following: (i) the overall understanding of fundamental concepts related to converging lenses, (ii) the understanding of specific concepts, and (iii) students' propensity for difficulties within this topic.
The initial ROC-CI consists of 16 multiple-choice items; however, one item was removed based on various quality checks.
We validated the ROC-CI thoroughly with distractor analyses, classical test theory, item response theory, structural analyses, and analyses of students' total scores at different measurement points as quantitative approaches, as well as student interviews and an expert survey as qualitative approaches. The quantitative analyses are mostly based on a dataset of N 1/4 318 middle school students who took the ROC-CI as a post-test. The student interviews were conducted with seven middle school students after they were taught the concepts of converging lenses.
The expert survey included five experts who evaluated both individual items and the test as a whole.
The analyses showed good to excellent results for the test instrument, corroborating the 15-item ROC-CI's validity and its compliance with the three foci outlined above.
We estimate the source parameters of small-magnitude earthquakes that occurred during 2008-2020 in the Irpinia faults area (southern Italy).
We apply a spectral decomposition approach to isolate the source contribution from propagation and site effects for similar to 3000 earthquakes in the local magnitude range between M-L 0 and 4.2.
We develop our analyses in three steps. First, we fit the Brune (1970) model to the nonparametric source spectra to estimate corner frequency and seismic moment, and we map the spatial distribution of stress drop across the Irpinia area.
We found stress drops in the range 0.4-8.1 MPa, with earthquakes deeper than 7 km characterized by higher average stress drop (i.e., 3.2 MPa).
Second, assuming a simple stress-release model (kanamori and Heaton, 2000), we derive fracture energy and critical slip-weakening distance. The spatial variability of stress drop and fracture energy allows us to image the present stress conditions of fault segments activated during the 23 November 1980 M-s 6.9 earthquake.
The variability of the source parameters shows clear patterns of the fault mechanical properties, suggesting that the Irpinia fault system can be divided into three main sectors, with the northern and southern ones showing different properties from the central one.
Our results agree with previous studies indicating the presence of fluids with different composition in the different sectors of the Irpinia fault system. In the third step, we compare the time evolution of source parameters with a time series of geodetic displacement recorded near the fault system.
Temporal trends in the correlation between geodetic displacement and different source parameters indicate that the poroelastic deformation perturbation generated by the karst aquifer recharge is modulating not only the occurrence rate of micro-seismicity ( D' Agostino et al., 2018) but may lead to rupture asperities with different sizes and characteristics.