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An expansion for a class of functions is called stable if the partial sums are bounded uniformly in the class. Stable expansions are of key importance in numerical analysis where functions are given up to certain error. We show that expansions in homogeneous functions are always stable on a small ball around the origin, and evaluate the radius of the largest ball with this property.
In order to investigate the temporal characteristics of cognitive processing, we apply multivariate phase synchronization analysis to event-related potentials. The experimental design combines a semantic incongruity in a sentence context with a physical mismatch (color change). In the ERP average, these result in an N400 component and a P300-like positivity, respectively. The synchronization analysis shows an effect of global desynchronization in the theta band around 288ms after stimulus presentation for the semantic incongruity, while the physical mismatch elicits an increase of global synchronization in the alpha band around 204ms. Both of these effects clearly precede those in the ERP average. Moreover, the delay between synchronization effect and ERP component correlates with the complexity of the cognitive processes.
Adsorption layers of soluble surfactants enable and govern a variety of phenomena in surface and colloidal sciences, such as foams. The ability of a surfactant solution to form wet foam lamellae is governed by the surface dilatational rheology. Only systems having a non-vanishing imaginary part in their surface dilatational modulus, E, are able to form wet foams. The aim of this thesis is to illuminate the dissipative processes that give rise to the imaginary part of the modulus. There are two controversial models discussed in the literature. The reorientation model assumes that the surfactants adsorb in two distinct states, differing in their orientation. This model is able to describe the frequency dependence of the modulus E. However, it assumes reorientation dynamics in the millisecond time regime. In order to assess this model, we designed a SHG pump-probe experiment that addresses the orientation dynamics. Results obtained reveal that the orientation dynamics occur in the picosecond time regime, being in strong contradiction with the two states model. The second model regards the interface as an interphase. The adsorption layer consists of a topmost monolayer and an adjacent sublayer. The dissipative process is due to the molecular exchange between both layers. The assessment of this model required the design of an experiment that discriminates between the surface compositional term and the sublayer contribution. Such an experiment has been successfully designed and results on elastic and viscoelastic surfactant provided evidence for the correctness of the model. Because of its inherent surface specificity, surface SHG is a powerful analytical tool that can be used to gain information on molecular dynamics and reorganization of soluble surfactants. They are central elements of both experiments. However, they impose several structural elements of the model system. During the course of this thesis, a proper model system has been identified and characterized. The combination of several linear and nonlinear optical techniques, allowed for a detailed picture of the interfacial architecture of these surfactants.
Stephen Jay Gould wrote recently that “when Church began to paint his great canvases, Alexander von Humboldt may well have been the world’s most famous and influential intellectual.” Humboldt’s influence in the case of the landscape artist Church is especially interesting. If we examine the precise relationship between the German explorer and his American admirer, we gain an insight into how Humboldt transformed Church’s life and signaled a new phase in the career of the artist. Church retraced Humboldt’s travels in Ecuador and in Mexico. If we compare the texts available to Church and the comparison of Church’s paintings and the texts and images of Humboldt’s works we can arrive at new perspectives on Humboldt’s extraordinary influence on American landscape painting in the nineteenth century.
The thesis assesses the contribution of technology option of Carbon Capture and Sequestration (CCS) to climate change mitigation. CCS means that CO2 is captured at large industrial facilities and sequestered in goelogical structures. The technology uses the endogenous growth model MIND. Herein the various climate change mitigation options of reducing economic growth, increasing energy efficiency, changing the energy mix and CCS are assessed simultaneously. An important question is whether CCS is a temporary or long-term solution. The results show that in the middle of the 21st century CCS has its peak contribution, which allows prolonged use of relatively cheap fossil energy carriers. However, this leads to delayed introduction of renewable energy carriers. The technology path ways are accombined with different costs of climate change mitigation. The use of CCS delays and reduces the costs of climate change mitigation. However, the delayed introduction of renewable energy carriers leads to reduced technological learning, which induces higher costs in the longer term. All in all the temporary use of CCS reduces the costs of climate change mitigation costs. The result is robust, which is tested with various uncertainty analysis.
In this thesis, we give two constructions for Riemannian metrics on Seiberg-Witten moduli spaces. Both these constructions are naturally induced from the L2-metric on the configuration space. The construction of the so called quotient L2-metric is very similar to the one construction of an L2-metric on Yang-Mills moduli spaces as given by Groisser and Parker. To construct a Riemannian metric on the total space of the Seiberg-Witten bundle in a similar way, we define the reduced gauge group as a subgroup of the gauge group. We show, that the quotient of the premoduli space by the reduced gauge group is isomorphic as a U(1)-bundle to the quotient of the premoduli space by the based gauge group. The total space of this new representation of the Seiberg-Witten bundle carries a natural quotient L2-metric, and the bundle projection is a Riemannian submersion with respect to these metrics. We compute explicit formulae for the sectional curvature of the moduli space in terms of Green operators of the elliptic complex associated with a monopole. Further, we construct a Riemannian metric on the cobordism between moduli spaces for different perturbations. The second construction of a Riemannian metric on the moduli space uses a canonical global gauge fixing, which represents the total space of the Seiberg-Witten bundle as a finite dimensional submanifold of the configuration space. We consider the Seiberg-Witten moduli space on a simply connected Käuhler surface. We show that the moduli space (when nonempty) is a complex projective space, if the perturbation does not admit reducible monpoles, and that the moduli space consists of a single point otherwise. The Seiberg-Witten bundle can then be identified with the Hopf fibration. On the complex projective plane with a special Spin-C structure, our Riemannian metrics on the moduli space are Fubini-Study metrics. Correspondingly, the metrics on the total space of the Seiberg-Witten bundle are Berger metrics. We show that the diameter of the moduli space shrinks to 0 when the perturbation approaches the wall of reducible perturbations. Finally we show, that the quotient L2-metric on the Seiberg-Witten moduli space on a Kähler surface is a Kähler metric.
From its first use in the field of biochemistry, instrumental analysis offered a variety of invaluable tools for the comprehensive description of biological systems. Multi-selective methods that aim to cover as many endogenous compounds as possible in biological samples use different analytical platforms and include methods like gene expression profile and metabolite profile analysis. The enormous amount of data generated in application of profiling methods needs to be evaluated in a manner appropriate to the question under investigation. The new field of system biology rises to the challenge to develop strategies for collecting, processing, interpreting, and archiving this vast amount of data; to make those data available in form of databases, tools, models, and networks to the scientific community. On the background of this development a multi-selective method for the determination of phytohormones was developed and optimised, complementing the profile analyses which are already in use (Chapter I). The general feasibility of a simultaneous analysis of plant metabolites and phytohormones in one sample set-up was tested by studies on the analytical robustness of the metabolite profiling protocol. The recovery of plant metabolites proved to be satisfactory robust against variations in the extraction protocol by using common extraction procedures for phytohormones; a joint extraction of metabolites and hormones from plant tissue seems practicable (Chapter II). Quantification of compounds within the context of profiling methods requires particular scrutiny (Chapter II). In Chapter III, the potential of stable-isotope in vivo labelling as normalisation strategy for profiling data acquired with mass spectrometry is discussed. First promising results were obtained for a reproducible quantification by stable-isotope in vivo labelling, which was applied in metabolomic studies. In-parallel application of metabolite and phytohormone analysis to seedlings of the model plant Arabidopsis thaliana exposed to sulfate limitation was used to investigate the relationship between the endogenous concentration of signal elements and the ‘metabolic phenotype’ of a plant. An automated evaluation strategy was developed to process data of compounds with diverse physiological nature, such as signal elements, genes and metabolites – all which act in vivo in a conditional, time-resolved manner (Chapter IV). Final data analysis focussed on conditionality of signal-metabolome interactions.
This work explores the equilibrium structure and thermodynamic phase behavior of complexes formed by charged polymer chains (polyelectrolytes) and oppositely charged spheres (macroions). Polyelectrolyte-macroion complexes form a common pattern in soft-matter physics, chemistry and biology, and enter in numerous technological applications as well. From a fundamental point of view, such complexes are interesting in that they combine the subtle interplay between electrostatic interactions and elastic as well as entropic effects due to conformational changes of the polymer chain, giving rise to a wide range of structural properties. This forms the central theme of theoretical studies presented in this thesis, which concentrate on a number of different problems involving strongly coupled complexes, i.e. complexes that are characterized by a large adsorption energy and small chain fluctuations. In the first part, a global analysis of the structural phase behavior of a single polyelectrolyte-macroion complex is presented based on a dimensionless representation, yielding results that cover a wide range of realistic system parameters. Emphasize is made on the interplay between the effects due to the polyelectrolytes chain length, salt concentration and the macroion charge as well as the mechanical chain persistence length. The results are summarized into generic phase diagrams characterizing the wrapping-dewrapping behavior of a polyelectrolyte chain on a macroion. A fully wrapped chain state is typically obtained at intermediate salt concentrations and chain lengths, where the amount of polyelectrolyte charge adsorbed on the macroion typically exceeds the bare macroion charge leading thus to a highly overcharged complex. Perhaps the most striking features occur when a single long polyelectrolyte chain is complexed with many oppositely charged spheres. In biology, such complexes form between DNA (which carries the cell's genetic information) and small oppositely charged histone proteins serving as an efficient mechanism for packing a huge amount of DNA into the micron-size cell nucleus in eucaryotic cells. The resultant complex fiber, known as the chromatin fiber, appears with a diameter of 30~nm under physiological conditions. Recent experiments indicate a zig-zag spatial arrangement for individual DNA-histone complexes (nucleosome core particles) along the chromatin fiber. A numerical method is introduced in this thesis based on a simple generic chain-sphere cell model that enables one to investigate the mechanism of fiber formation on a systematic level by incorporating electrostatic and elastic contributions. As will be shown, stable complex fibers exhibit an impressive variety of structures including zig-zag, solenoidal and beads-on-a-string patterns, depending on system parameters such as salt concentration, sphere charge as well as the chain contour length (per sphere). The present results predict fibers of compact zig-zag structure within the physiologically relevant regime with a diameter of about 30~nm, when DNA-histone parameters are adopted. In the next part, a numerical method is developed in order to investigate the role of thermal fluctuations on the structure and thermodynamic phase behavior of polyelectrolyte-macroion complexes. This is based on a saddle-point approximation, which allows to describe the experimentally observed reaction (or complexation) equilibrium in a dilute solution of polyelectrolytes and macroions on a systematic level. This equilibrium is determined by the entropy loss a single polyelectrolyte chain suffers as it binds to an oppositely charged macroion. This latter quantity can be calculated from the spectrum of polyelectrolyte fluctuations around a macroion, which is determined by means of a normal-mode analysis. Thereby, a stability phase diagram is obtained, which exhibits qualitative agreement with experimental findings. At elevated complex concentrations, one needs to account for the inter-complex interactions as well. It will be shown that at small separations, complexes undergo structural changes in such a way that positive patches from one complex match up with negative patches on the other. Furthermore, one of the polyelectrolyte chains may bridge between the two complexes. These mechanisms lead to a strong inter-complex attraction. As a result, the second virial coefficient associated with the inter-complex interaction becomes negative at intermediate salt concentrations in qualitative agreement with recent experiments on solutions of nucleosome core particles.
Connective ties in discourse: Three ERP studies on causal, temporal and concessive connective ties and their influence on language processing. Questions In four experiments the influence of lexical connectives such as " darum", therefore, " danach", afterwards, and " trotzdem", nevertheless, on the processing of short two-sentence discourses was examined and compared to the processing of deictical sentential adverbs such as " gestern", yesterday, and " lieber", rather. These latter words do not have the property of signaling a certain discourse relation between two sentences, as connective ties do. Three questions were central to the work: * Do the processing contrasts found between connective and non-connective elements extend to connective ties and deictical sentential adverbs (experiments 2 and 3)? * Does the semantic content of the connective ties play the primary role, i.e is the major distinction to be made indeed between connective and non-connective or instead between causal, temporal and concessive? * When precisely is the information provided by connective ties used? There is some evidence that connective ties can have an immediate influence on the integration of subsequent elements, but the end of the second sentences appears to play an important role as well: experiments 2, 3, and 4. Conclusions First of all, the theoretical distinction between connective and non-connective elements does indeed have " cognitive reality" . This has already been shown in previous studies. The present studies do however show, that there is also a difference between one-place discourse elements (deictical sentential adverbs) and two-place discourse elements, namely connective ties, since all experiments examining this contrast found evidence for qualitatively and quantitatively different processing (experiments 1, 2, and 3). Secondly, the semantic type of the connective ties also plays a role. This was not shown for the LAN, found for all connective ties when compared to non-connective elements, and consequently interpreted as a more abstract reflection of the integration of connective ties. There was also no difference between causal and temporal connective ties before the end of the discourses in experiment 3. However, the N400 found for incoherent discourses in experiment 2, larger for connective incoherent than non-connective incoherent discourses, as well as the P3b found for concessive connective ties in the comparison between causal and concessive connective ties gave reason to assume that the semantic content of connective ties is made use of in incremental processing, and that the relation signaled by the connective tie is the one that readers attempt to construct. Concerning when the information provided by connective ties is used, it appears as if connectivity is generally and obligatorily taken at face value. As long as the meaning of a connective tie did not conflict with a preferred canonical discourse relation, there were no differences found for varying connective discourses (experiment 3). However, the fact that concessive connective ties announce the need for a more complex text representation was recognized and made use of immediately (experiment 4). Additionally, a violation of the discourse relation resulted in more difficult semantic integration if a connective tie was present (experiment 2). It is therefore concluded here that connective ties influence processing immediately. This claim has to be modified somewhat, since the sentence-final elements suggested that connective ties trigger different integration processes than non-connective elements. It seems as if the answer to the question of when connective ties are processed is neither exclusively immediately nor exclusively afterwards, but that both viewpoints are correct. It is suggested here that before the end of a discourse economy plays a central role in that a canonical relation is assumed unless there is evidence to the contrary. A connective tie could have the function of reducing the dimensions evaluated in a discourse to the one signaled by the connective tie. At the end of the discourse the representation is evaluated and verified, and an integrated situation model constructed. Here, the complexity of the different discourse relations that connective ties can signal, is expressed.
We study (pseudo-)differential operators on a manifold with edge Z, locally modelled on a wedge with model cone that has itself a base manifold W with smooth edge Y . The typical operators A are corner degenerate in a specific way. They are described (modulo ‘lower order terms’) by a principal symbolic hierarchy σ(A) = (σ ψ(A), σ ^(A), σ ^(A)), where σ ψ is the interior symbol and σ ^(A)(y, η), (y, η) 2 T*Y \ 0, the (operator-valued) edge symbol of ‘first generation’, cf. [15]. The novelty here is the edge symbol σ^ of ‘second generation’, parametrised by (z, Ϛ) 2 T*Z \ 0, acting on weighted Sobolev spaces on the infinite cone with base W. Since such a cone has edges with exit to infinity, the calculus has the problem to understand the behaviour of operators on a manifold of that kind. We show the continuity of corner-degenerate operators in weighted edge Sobolev spaces, and we investigate the ellipticity of edge symbols of second generation. Starting from parameter-dependent elliptic families of edge operators of first generation, we obtain the Fredholm property of higher edge symbols on the corresponding singular infinite model cone.
Operators on a manifold with (geometric) singularities are degenerate in a natural way. They have a principal symbolic structure with contributions from the different strata of the configuration. We study the calculus of such operators on the level of edge symbols of second generation, based on specific quantizations of the corner-degenerate interior symbols, and show that this structure is preserved under compositions.
In this thesis the magnetohydrodynamic jet formation and the effects of magnetic diffusion on the formation of axisymmetric protostellar jets have been investigated in three different simulation sets. The time-dependent numerical simulations have been performed, using the magnetohydrodynamic ZEUS-3D code.
Strong damped Lyman alpha absorption (DLA) lines seen spectra of distant quasar are believed to arise when the sight line to the quasar goes trough the disc of a galaxy or a proto galaxy. Most of the neutral matter in the universe is contained in these clouds of neutral hydrogen that cause the absorption lines. Hence these DLAs are reservoirs for the formation of stars and galaxies throughout the universe. Despite intensive efforts over more than two decades only few galaxies responsible for the DLAs have been found. The problem is that the galaxies that harbour the neutral clouds are not necessarily bright, and selecting galaxies based on absorption lines could well select different types of galaxies than found in large surveys. If we are to understand how galaxies form out of neutral gas clouds it is essential to locate the galaxies in which DLAs reside. This thesis explores the use of integral field spectroscopy (IFS) to observe quasars known to have strong absorption lines in their spectra. IFS allows us to obtain a spectrum at many spatial points close to the quasar, thus providing images and spectroscopy simultaneously. From the imaging part, we can directly identify objects, and from the spectroscopy we can calculate the distances to the objects. When the distance of the object found in emission matches the distance to the object that cause the DLA line, we have identified the absorbing galaxy. Using this technique, we have showed that we can successfully recover a few DLA galaxies known previously from the literature. In a survey aimed to increase the number of DLA galaxies we have identified eight new candidate DLA galaxies. The projected distances from the candidates to the quasar sight lines indicate that the DLA galaxies have sizes similar to local disc galaxies. Hence our results suggest that large discs may be present when the universe was just 2 billion years old. We furthermore find no differences between the sizes of the very distant DLA galaxies and those that are not so distant. The large sizes imply that their neutral hydrogen masses are also similar to those in local galaxies, but we argue that the DLA galaxies are not necessarily as luminous as the present day disc galaxies. Taking advantage of the three-dimensional view provided by the IFS data, the second part of this thesis investigates extended emission line regions arising in the quasar neighborhood. We find that extended emission line nebulae are common around quasars, and explore the effects that may be the cause. Some quasars are known to be powerful radio emitters while others are not detected at radio wavelengths. We find that significantly larger and brighter emission line nebulae are found around the quasars which have the brightest radio emission, and in particular those that have large radio jets. The existence of the nebulae can be interpreted as an interaction of the radio jet with the surrounding medium, but we can not rule out a scenario where there are density or temperature differences in the surrounding environment. Only for the brightest object, where additional velocity information can be derived from the IFS data, can we argue for an interaction. In conclusion the use of IFS to search for faint emission lines, both from point sources and extended nebulae provides exciting new results within the scientific areas studied here.
Alexander von Humboldt’s descriptions of volcanic mountains in his travel journals (Reise auf dem Río Magdalena, durch die Anden und Mexico) show both his reliance on and impatience with literary conventions and travel narratives. Using Goethe’s Italienische Reise and Bürger’s Münchhausen as points of comparison for literary treatments of the volcano ascent, Humboldt’s process of writing is examined. Humboldt shows the failure of the existing discourse and begins to experiment with narratives which fragment and recombine personal and historical modes of writing with, in this case, images from new technical inventions which visualize landscape according to fundamental scientific principles. While the inclusion of scientific prose is relevant, Humboldt’s link to modernity is based on experimental narrative techniques which draw upon changing sets of discourse practices to describe complex realities.
Nitrogen is an essential macronutrient for plants and nitrogen fertilizers are indispensable for modern agriculture. Unfortunately, we know too little about how plants regulate their use of soil nitrogen, to maximize fertilizers-N use by crops and pastures. This project took a dual approach, involving forward and reverse genetics, to identify N-regulators in plants, which may prove useful in the future to improve nitrogen-use efficiency in agriculture. To identify nitrogen-regulated transcription factor genes in Arabidopsis that may control N-use efficiency we developed a unique resource for qRT-PCR measurements on all Arabidpsis transcription factor genes. Using closely spaced, gene-specific primer pairs and SYBR® Green to monitor amplification of double-stranded DNA, transcript levels of 83% of all target genes could be measured in roots or shoots of young Arabidopsis wild-type plants. Only 4% of reactions produced non-specific PCR products, and 13% of TF transcripts were undetectable in these organs. Measurements of transcript abundance were quantitative over six orders of magnitude, with a detection limit equivalent to one transcript molecule in 1000 cells. Transcript levels for different TF genes ranged between 0.001-100 copies per cell. Real-time RT-PCR revealed 26 root-specific and 39 shoot-specific TF genes, most of which have not been identified as organ-specific previously. An enlarged and improved version of the TF qRT-PCR platform contains now primer pairs for 2256 Arabidopsis TF genes, representing 53 gene families and sub-families arrayed on six 384-well plates. Set-up of real-time PCR reactions is now fully robotized. One researcher is able to measure expression of all 2256 TF genes in a single biological sample in a just one working day. The Arabidopsis qRT-PCT platform was successfully used to identify 37 TF genes which transcriptionaly responded at the transcriptional level to N-deprivation or to nitrate per se. Most of these genes have not been characterized previously. Further selection of TF genes based on the responses of selected candidates to other macronutrients and abiotic stresses allowed to distinguish between TFs regulated (i) specifically by nitrogen (29 genes) (ii) regulated by general macronutrient or by salt and osmotic stress (6 genes), and (iii) responding to all major macronutrients and to abiotic stresses. Most of the N-regulated TF genes were also regulated by carbon. Further characterization of sixteen selected TF genes, revealed: (i) lack of transcriptional response to organic nitrogen, (ii) two major types of kinetics of induction by nitrate, (iii) specific responses for the majority of the genes to nitrate but not downstream products of nitrate assimilation. All sixteen TF genes were cloned into binary vectors for constitutive and ethanol inducible over expression, and the first generation of transgenic plants were obtained for almost all of them. Some of the plants constitutively over expressing TF genes under control of the 35S promoter revealed visible phenotypes in T1 generation. Homozygous T-DNA knock out lines were also obtained for many of the candidate TF genes. So far, one knock out line revealed a visible phenotype: retardation of flowering time. A forward genetic approach using an Arabidopsis ATNRT2.1 promoter : Luciferase reporter line, resulted in identification of eleven EMS mutant reporter lines affected in induction of ATNRT2.1 expression by nitrate. These lines could by divided in the following classes according to expression of other genes involved in primary nitrogen and carbon metabolism: (i) lines affected exclusively in nitrate transport, (ii) those affected in nitrate transport, acquisition, but also in glycolysis and oxidative pentose pathway, (iii) mutants affected moderately in nitrate transport, oxidative pentose pathway and glycolysis but not in primary nitrate assimilation. Thus, several different N-regulatory genes may have been mutated in this set of mutants. Map-based cloning has begun to identify the genes affected in these mutants.
This article examines the multiple governments of independent Estonia since 1992 referring to their stability. Confronted with the immense problems of democratic transition, the multi-party governments of Estonia change comparatively often. Following the elections of March 2003 the ninth government since 1992 was formed. A detailed examination of government stability and the example of Estonia is accordingly warranted, given that the country is seen as the most successful Central Eastern European transition country in spite of its frequent changes of government. Furthermore, this article questions whether or not internal government stability can exist within a situation where the government changes frequently. What does stability of government mean and what are the varying multi-faceted depths of the term? Before analysing the term, it has to be clarified and defined. It is presumed that government stability is composed of multiple variables influencing one another. Data about the average tenure of a government is not very conclusive. Rather, the deeper political causes for governmental change need to be examined. Therefore, this article discusses the conceptual and theoretical basics of governmental stability first. Secondly, it discusses the Estonian situation in detail up to the elections of 2003, including a short review of the 9th government since independence. In the conclusion, the author explains whether or not the governments of Estonia are stable. In the appendix, the reader finds all election results and also a list of all previous ministers of Estonian governments (all data are as of July 2002).
In an experimental study the attempt was made to examine the effects of the Reciprocal Teaching method on measures of metacognition and try to identify the effective features of this method that are necessary for the learning gains to occur. Reciprocal Teaching, originally developed by Palincsar and Brown (1984), is a very successful training program which was designed to improve student's reading comprehension skills by teaching them reading strategies. In the present study the tasks and responsibilities assumed by 5thgrade elementary students (N = 55) participating in a 16-session reading strategy training were varied systematically. Not only the students who participated in the training program in one of the three experimental conditions were compared with respect to knowledge and performance measures, but there was also a comparison to their control classmates who did not participate in strategy training (N = 86). Detailed analyses of video-taped sessions provided additional information. The strategy training was most beneficial for measures of knowledge and performance more closely related to the content of the training program, namely knowledge about specific reading strategies taught in training and application of those strategies. No significant effects were observed for more distal measures (general strategy knowledge, reading comprehension). As for the features of the program, it could be shown that students of the two experimental conditions where the students were responsible for giving each other feedback on performance (with respect to both content and strategy application) and guiding the correction of the answer outperformed both the experimental condition in which the trainer was responsible for those tasks and the control group. It is concluded that it is not merely the application of strategies, but the combination of strategy application with concurrent teaching and learning of metacognitive acquisition procedures (analysis, monitoring, evaluation, and regulation) in an inter-individual way as the precedent of these processes occurring intra-individually that seems to be an efficient way of acquiring metacognitive knowledge and skills. It was also shown that strategy training does not necessarily have to include the precise kind of interaction that characterizes the Reciprocal Teaching method. Instead, the tasks of monitoring, evaluating, and regulating other children's learning processes - i.e., tasks associated with the "teacher role" - are the ones that promote the acquisition of metacognitive knowledge and skills. Generally, any strategy training program that not only provides children with plentiful opportunities for practice, but also prompts them to engage in these kinds of metacognitive processes, may help children to acquire metacognitive knowledge and skills.
The Humboldt Digital Library
(2005)
Alexander von Humboldt’s maps, graphs and illustrations contain a great deal of detail, but in the available rare editions they are hardly visible to the naked eye. In many editions they have been reduced. In a digital library, they will become accessible in their entirety, and Internet technology will reproduce them in a form that overcomes the limitations of the original printing. The user will be able to enlarge the images and see details that might have been overlooked in the past. The Humboldt’s digital library will adhere to the standards for digital libraries established by the Open Archives Initiative (OAI) and the tools EPRINTS and DSPACE to provide the Web services and determine the most effective way to establish dynamic linking and knowledge based searching of information within the archive.
The multidrug and toxic compounds extrusion (MATE) family includes hundreds of functionally uncharacterised proteins from bacteria and all eukaryotic kingdoms except the animal kingdom, that function as drug/toxin::Na<sup>+ or H<sup>+ antiporters. In Arabidopsis thaliana the MATE family comprises 56 members, one of which is NIC2 (Novel Ion Carrier 2). Using heterologous expression systems including Escherichia coli and Saccharomyces cerevisiae, and the homologous expression system of Arabidopsis thaliana, the functional characterisation of NIC2 was performed. It has been demonstrated that NIC2 confers resistance of E. coli towards the chemically diverse compounds such as tetraethylammonium chloride (TEACl), tetramethylammonium chloride (TMACl) and a toxic analogue of indole-3-acetic acid, 5-fluoro-indole-acetic acid (F-IAA). Therefore, NIC2 may be able to transport a broad range of drug and toxic compounds. In wild-type yeast the expression of NIC2 increased the tolerance towards lithium and sodium, but not towards potassium and calcium. In A. thaliana, the overexpression of NIC2 led to strong phenotypic changes. Under normal growth condtions overexpression caused an extremely bushy phenotype with no apical dominance but an enhanced number of lateral flowering shoots. The amount of rossette leaves and flowers with accompanying siliques were also much higher than in wild-type plants and the senescence occurred earlier in the transgenic plants. In contrast, RNA interference (RNAi) used to silence NIC2 expression, induced early flower stalk development and flowering compared with wild-type plants. In additon, the main flower stalks were not able to grow vertically, but instead had a strong tendency to bend towards the ground. While NIC2 RNAi seedlings produced many lateral roots outgrowing from the primary root and the root-shoot junction, NIC2 overexpression seedlings displayed longer primary roots that were characterised by a 2 to 4 h delay in the gravitropic response. In addition, these lines exhibited an enhanced resistance to exogenously applied auxins, i.e. indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) when compared with the wild-type roots. Based on these results, it is suggested that the NIC2 overexpression and NIC2 RNAi phenotypes were due to decreased or increased levels of auxin, respectively. The ProNIC2:GUS fusion gene revealed that NIC2 is expressed in the stele of the elongation zone, in the lateral root cap, in new lateral root primordia, and in pericycle cells of the root system. In the vascular tissue of rosette leaves and inflorescence stems, the expression was observed in the xylem parenchyma cells, while in siliques it was also in vascular tissue, but as well in the dehiscence and abscission zones. The organ- and tissue-specific expression sites of NIC2 correlate with the sites of auxin action in mature Arabidopsis plants. Further experiments using ProNIC2:GUS indicated that NIC2 is an auxin-inducible gene. Additionally, during the gravitropic response when an endogenous auxin gradient across the root tip forms, the GUS activity pattern of the ProNIC2:GUS fusion gene markedly changed at the upper side of the root tip, while at the lower side stayed unchanged. Finally, at the subcellular level NIC2-GFP fusion protein localised in the peroxisomes of Nicotana tabacum BY2 protoplasts. Considering the experimental results, it is proposed that the hypothetical function of NIC2 is the efflux transport which takes part in the auxin homeostasis in plant tissues probably by removing auxin conjugates from the cytoplasm into peroxisomes.
Many European countries have experienced a significant increase of unemployment in recent years. This paper reviews several theoretical models that try to explain this phenomenon. Predominantly, these models claim a link between the poor performance of European labor markets and the high level of market regulation. Commonly referred to as the Eurosclerosis debate, prominent approaches consider insider-outsider relationships, search-models, and the influence of hiring and firing costs on equilibrium employment. The paper presents empirical evidence of each model and studies the relevance of the identified rigidities as a determinant of high unemployment in Europe. Furthermore, a case study analyzes the unemployment problem in Germany and critically discusses new reform efforts. In particular this section analyzes whether the recently enacted Hartz reforms can induce higher employment.