1,560 research outputs found
FiFoSiM - an integrated tax benefit microsimulation and CGE model for Germany
No full textThis paper describes FiFoSiM, the integrated tax benefit microsimulation and computable general equilibrium (CGE) model of the Center of Public Economics at the University of Cologne. FiFoSiM consists of three main parts. The first part is a static tax benefit microsimulation module. The second part adds a behavioural component to the model; an econometrically estimated labour supply model. The third module is a CGE model which allows the user of FiFoSiM to assess the global economic effects of policy measures. Two specific features distinguish FiFoSiM from other tax benefit models: First, the simultaneous use of two databases for the tax benefit module and second, the linkage of the tax benefit model to a CGE model.FiFoSiM; microsimulation; CGE
The Benefits and Problems of Linking Micro and Macro Models: Evidence from a Flat Tax Analysis
No full textMicrosimulation (MS) and Computable General Equilibrium models (CGE) have both been widely used in policy analysis. Their combination allows the utilisation of the advantages of both types. The aim of this paper is to describe the state-of-the-art in simulation analysis and to illustrate the benefits and problems of linking micro and macro models by analysing flat tax reform proposals for Germany. Taking feedback effects into account has important implications for the evaluation of tax reforms. The analysis shows that a personal income flat tax can indeed overcome the fundamental equity efficiency trade-off while simultaneously increasing the tax revenue. However, this result does not hold for a flat tax combining a personal income flat tax with a corporate cash flow flat tax, even when allowing for an ex-post loss in revenue as the top of the distribution still gains the most.Microsimulation, CGE, linked micro macro models, flat tax
Mechanical response of adherent giant liposomes to indentation with a conical AFM-tip
No full textIndentation of giant liposomes with a conical indenter is described by means of a tension-based membrane model. We found that nonlinear membrane theory neglecting the impact of bending sufficiently describes the mechanical response of liposomes to indentation as measured by atomic force microscopy. Giant vesicles are gently adsorbed on glassy surfaces via avidin-biotin linkages and indented centrally using an atomic force microscope equipped with conventional sharp tips mounted on top of an inverted microscope. Force indentation curves display a nonlinear response that allows to extract pre-stress of the bilayer T-0 and the area compressibility modulus K-A by computing the contour of the vesicle at a given force. The values for K-A of fluid membranes correspond well to what is known from micropipet suction experiments and inferred from membrane undulation monitoring. Assembly of actin shells inside the liposome considerably stiffens the vesicles resulting in significantly larger area compressibility modules. The analysis can be easily extended to different indenter geometries with rotational symmetry.[SFB 803 (B08)
Greek and Latin Expressions of Meaning
No full textVerbs and nouns of meaning in ancient Greek and Latin are polysemous, just as in the case of the English verb “to mean". Andreas T. Zanker considers how the ancient vocabulary could be used in different ways and investigates its development over time. In the first part of the book, Zanker argues for the role of metaphorical and metonymical transference in the creation of expressions of meaning; Greek and Roman authors used the same verbs to describe what inanimate things, including words and texts, meant/signified as they did of human beings in the act of meaning/signifying something. In the second part of the book, the author focuses on certain metaphorical extensions of this vocabulary and argues that they have implications for modern discussions of meaning, particularly in literary criticism.Verben und Substantive des Bedeutens sind mehrdeutig auf Altgriechisch und Latein. Andreas T. Zanker überlegt, wie das antike Vokabular in unterschiedlicher Weise benutzt werden konnte, und untersucht seine Entwicklung im Laufe der Zeit. Im ersten Teil des Buches argumentiert Zanker für die Rolle von metaphorischer und metonymischer Übertragung bei der Entstehung von Ausdrücken des Bedeutens; griechische und römische Schriftsteller benutzten die gleichen Verben, um die Bedeutungen von unbelebten Gegenständen (einschließlich Wörtern und Texten) wie auch die Absichten und Intentionen von Menschen zu artikulieren. Im zweiten Teil des Buches fokussiert der Autor auf gewisse metaphorische Ausdehnungen des Wortschatzes und behauptet, dass sie Implikationen für moderne Diskussionen über Bedeutung haben – insbesondere in der Literaturwissenschaft und Philologie
Tree species diversity versus tree species identity: Driving forces in structuring forest food webs as indicated by soil nematodes
No full textPositive relationships between biodiversity and ecosystem functioning are reported in many studies. The underlying mechanisms are, however, only little understood, likely due to the focus on the aboveground system and neglecting species-specific traits. We used different clusters of tree species composition to investigate how tree species diversity and tree species identity affect belowground nematode communities. Since soil nematodes comprise different trophic groups and are strongly linked to the microbial community, results can provide insight on how soil food webs are structured. In addition, data on leaf litter and fine root biomass were included to account for different effects of aboveground and belowground resources. Clusters of three trees of one, two and three species were identified within a temperate deciduous forest. Target tree species were European beech (Fagus sylvatica), common ash (Fraxinus excelsior) and lime (Tilia cordata, T. platyphyllos) differing in physiology, leaf litter quality and type of mycorrhiza. Tree species identity strongly affected nematode trophic structure, whereas tree Species diversity had no impact. Ash beneficially affected bacterial-feeding nematodes, whereas fungal feeders were suppressed, likely caused by ash litter increasing soil pH. Fostering of the bacterial food chain by ash additionally could be related to rhizodeposition gaining importance after disappearance of high quality ash litter in spring, highlighting seasonal shifts in root and leaf litter-derived resources. The negative effect of ash on fungal-feeding nematodes is suggested to be due to the lack of ectomycorrhizal fungi as ash roots only form arbuscular mycorrhiza. In contrast, beech benefited fungal feeders and detrimentally affected bacterial feeders due to more acidic soil conditions that increase the competitive strength of fungi. Lime tended to negatively impact total nematode density but positively influenced plant-feeding nematodes. Generally, beech and ash strongly but opposingly influenced the trophic structure of nematode communities suggesting that changes in tree species identity result in major shifts in the channeling of energy through decomposer food webs. The results indicate that the structure of soil food webs varies markedly with tree species and point to the importance of basal resources, i.e., leaf litter and rhizodeposits. This suggests bottom-up forces mediated by individual tree species to control major decomposition pathways rather than tree diversity. (C) 2013 Elsevier Ltd. All rights reserved
Architecture of a mammalian glomerular domain revealed by novel volume electroporation using nanoengineered microelectrodes
No full textDense microcircuit reconstruction techniques have begun to provide ultrafine insight into the architecture of small-scale networks. However, identifying the totality of cells belonging to such neuronal modules, the “inputs” and “outputs,” remains a major challenge. Here, we present the development of nanoengineered electroporation microelectrodes (NEMs) for comprehensive manipulation of a substantial volume of neuronal tissue. Combining finite element modeling and focused ion beam milling, NEMs permit substantially higher stimulation intensities compared to conventional glass capillaries, allowing for larger volumes configurable to the geometry of the target circuit. We apply NEMs to achieve near-complete labeling of the neuronal network associated with a genetically identified olfactory glomerulus. This allows us to detect sparse higher-order features of the wiring architecture that are inaccessible to statistical labeling approaches. Thus, NEM labeling provides crucial complementary information to dense circuit reconstruction techniques. Relying solely on targeting an electrode to the region of interest and passive biophysical properties largely common across cell types, this can easily be employed anywhere in the CNS
Relative importance of predators and parasitoids for cereal aphid control
No full textField experiments with manipulations of natural enemies of plant–feeding insects may show how a diverse enemy group ensures an important ecosystem function such as naturally occurring biological pest control. We studied cereal aphid populations in winter wheat under experimentally reduced densities of: (i) ground–dwelling generalist predators (mostly spiders, carabid and staphylinid beetles); (ii) flying predators (coccinellid beetles, syrphid flies, gall midges, etc.) and parasitoids (aphidiid wasps), and a combination of (i) and (ii), compared with open controls. Aphid populations were 18% higher at reduced densities of ground–dwelling predators, 70% higher when flying predators and parasitoids were removed, and 172% higher on the removal of both enemy groups. Parasitoid wasps probably had the strongest effect, as flying predators occurred only in negligible densities. The great importance of parasitism is a new finding for aphid control in cereal fields. In conclusion, a more detailed knowledge of the mechanisms of natural pest control would help to develop environmentally sound crop management with reduced pesticide applications
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