Publication Server of Constructor University Library
Not a member yet
858 research outputs found
Sort by
Cellular localization of anthropogenic contaminants and related biological effects in the blue mussel Mytilus edulis
No full textUnderstanding the uptake, intracellular transport processes and fate of chemicals as well as their biotransformation and elimination is essential to provide information about potential health risks of environmental pollutants for exposed organisms. Moreover, this knowledge helps to identify biomarkers suitable for the use in monitoring studies of health effects of chemicals in marine organisms. To address this issue, an immunocytochemical approach was developed for the cellular and subcellular detection of chemicals. Based on the newly implemented antibody-based detection techniques the intracellular trafficking of lipophilic organic pollutants and the heavy metal lead (Pb) was studied. Induction of relevant biotransformation and pathological alterations at the subcellular level were investigated in parallel. Accumulation of PCBs, PAHs and the metal Pb were shown in the endo-lysosomal system of the cell. We could evidence that the contaminants accumulate in cell organelles which are known to play an important role in metabolic regulation as well as sequestration and detoxification processes. Moreover, we also localized the chemicals in association to subcellular structures and organelles such as mitochondria and nuclei where accumulation of those pollutants is particularly hazardous. Laboratory studies with phenanthrene as a lipophilic organic contaminant and with Pb as a heavy metal showed distinct responses of phase I and phase II enzymes as well as catalase, a general marker enzyme for oxidative stress. Pathological changes were investigated at the subcellular level. In parallel, the distribution of the contaminants was analysed with the developed antibody-based detection technique to elucidate direct toxicant-induced effects. Our results revealed specific accumulation sites in the cells for the environmental pollutants which were related to specific pathological alterations of these cell organelles
The role of the chromatin protein HU in organization of transcription foci and coordination of genomic transcription in Escherichia coli
No full textThe process of transcription is intimately linked to the overall structure and superhelicity of DNA in the context of bacterial nucleoid. The structure of the nucleoid in Escherichia coli depends in part on the composition of nucleoid-associated proteins, which is changing with growth phase. In order to understand the influence of the nucleoid structure on gene expression, studies of genomic transcript profiles of mutants lacking nucleoid proteins have to be complemented by approaches revealing the mechanistic basis of nucleoid-shaping processes. In this study, the localization of RNA polymerase in several mutants of nucleoid-associated proteins was investigated and found to be dependent on the major nucleoid-associated protein HU. The HU mutant showed a spatial defect in coordinating gene expression. More specifically, genes located within a large region comprising OriC and bordered by the last ribosomal RNA genes on both arms of the chromosome were expressed stronger than in wild type. This defect is most easily explained by disturbances of effective DNA supercoiling - a variable modulating promoter activities - in the mutant lacking HU. This work proposes a holistic model explaining the HU-dependent spatial localization of RNAP and coordination of gene expression by means of gross DNA structures formed upon cooperative binding of HU, as opposed to the classical perspective emphasizing the rearrangements of interactions within a "digital" regulatory network. Defects in the transcriptional response of HU mutant to stress are easily accommodated in our general model. Moreover, this model proposes a novel autoregulatory mechanism implicating a self-organizing nucleoid structure in coordinating genomic transcription. By assuming the role of structural autoregulation of the entire bacterial genome in coordination of global transcription, this model may also provide insights into the mechanistic basis of cell differentiation in multicellular organisms
Bedeutung und Verwendung der Begriffe nachhaltige Entwicklung und Nachhaltigkeit : eine empirische Studie
No full textSustainable development has been enriched by notions and views presented by related scientific and political discourses as well as by other actors' implicit views on sustainable development. This plethora of opinions is due to highly diverse parts of society participating in the discourse. The assumption is made that due to its abstractness, the sustainable development concept can overcome strong barriers between social systems like science, economy, politics or education. This leads to a secondary communication problem: once absorbed by the social subsystems, the abstract meaning of sustainable development is adapted to and diluted by the system's specific language. With adaptation, the communication barrier between the systems arises again, due to the different meanings that they attribute to the adjusted versions of sustainable development. This thesis therefore sets out to present a first empirical study on the meaning of sustainable development. In a theoretical discussion, a distinction is made between a denotative and connotative meaning. Scientist, politicians and economists usually discuss the denotation, in other words, the literal meaning of sustainable development. Sustainable development's connotation is, however, important for sustainable development education in general and, even more importantly, in the mass media with its focus on entertainment and on inducing moods and emotions. In this thesis, a content analysis method is used to assess the denotation of sustainable development for the economic and political system. The data obtained support the assumption that sustainable development has different meanings for different actors and systems. Furthermore, a large online survey was conducted by means of the semantic differential technique to determine the connotation of sustainable development. It revealed several interesting results, one of which was that the connotation differs with the degree of familiarity with the concept
Echo State Networks with Trained Feedbacks
No full textEcho State Networks (ESNs) is an approach to the recurrent neural network (RNN) training, based on generating a big random network (reservoir) of sparsely inter-connected neurons and learning only a single layer of output weights from the reservoir as the target function. Despite many advantages of ESNs over gradient based RNN training techniques, they lack the power of learning some complex functions. New findings in dynamical systems theory state, that fixed neural circuits can obtain universal computational qualities if suitable feedbacks (or intermediate units) can be trained. Unfortunately the theory gives no hint on how this can be done. In this report we explore possible directions in which the theoretical findings could be applied to increase the computational power of ESNs. More specifically, we discuss possible options for defining training targets for the feedbacks, present and discuss some empirical results (positive as well as negative) testing the ideas in practice and analyze some problems pointing out to some intrinsic limitations of ESNs. Another contribution of this report is a discussion of many practical issues of training ESNs in particular the ones having feedback connections. We also propose a modification of ESNs called Layered ESNs. This technical report is based on the author’s Master Thesis named "Improving Echo State Networks by Training Intermediate Units"
Going beyond information given : how approach versus avoidance motivational cues influence encoding of meaning and details
No full textIn five studies we investigated how approach versus avoidance motivational cues affect thinking styles. Based on the cognitive tuning account we proposed that approach motivation facilitates abstract thinking and impedes concrete thinking, whereas the reverse is true for avoidance motivation. Individuals with an approach motivation go beyond the information given and focus on its central meaning, whereas individuals with an avoidance motivation focus on the externally provided information and attend to the specifics and contextual features of the information at hand. Two experiments using the perceptual interference paradigm that distinguishes between encoding of meaning and perceptual details demonstrated the influence of motivational cues on thinking styles: Participants engaging in arm flexion (approach motivation) recalled more perceptual interference than intact items, which is attributed to higher-level, interpretative encoding operations; participants engaging in arm extension (avoidance motivation) recalled more intact than perceptual interference items, which is attributed to elaborative encoding operations that go beyond the immediate interpretation and examine the distinctive stimulus characteristics. Two subsequent experiments demonstrated that encoding of perceptual interference versus intact items is bidirectionally linked to global versus local perception, suggesting that both courses of action involve processing structural relations among elements or, respectively, of perceptual details. The fifth experiment showed that participants with an approach motivation processed abstract why-aspects of action more fluently than concrete how-aspects of action, whereas participants with an avoidance motivation processed how-aspects more fluently than why-aspects. Altogether, the results suggest a functional compatibility between motivational orientations and thinking styles. Implications for research on person perception and text understanding are discussed
Cathartic effects revisited : the impacts of goals on aggressive thoughts and aggressive behavior
No full textA functional look at the catharsis hypothesis is investigated. The basic assumption of the model is that the goal to aggress increases aggression-related constructs. Furthermore, it is assumed that this heightened accessibility of aggression-related constructs loses its functionality after goal-fulfillment. Therefore, it is claimed that after goal-fulfillment accessibility of aggression-related constructs decreases. It is also expected that aggressive behavior is reduced after goal-fulfillment. Study 1 to 3 examined whether fulfilling an aggressive goal reduces aggression. Study 1 showed an increase of aggression-related constructs after priming the goal to aggress via a fictitious scenario compared to a control scenario. After imagined and symbolic goal-fulfillment the accessibility of aggression-related constructs was reduced. Study 2 showed that after fulfilling the goal to aggress aggressive behavior was reduced. In addition, a non-aggressive way of goal-fulfillment reduced aggressive behavior even more. Study 3 demonstrated that goal-fulfillment is necessary for reducing accessibility of aggression-related constructs. Without goal-fulfillment fictitious aggressive acts against an unrelated target/inanimate object increase aggression. Study 4 tested an alternative explanation for post-fulfillment reduction in accessibility, namely thought-suppression. In general, thought suppression leads to heightened accessibility of thoughts in a group that was instructed to suppress these thoughts compared to a non-suppression group (rebound effect). Participants who were instructed to suppress aggressive thoughts had more accessible aggressive thoughts than a group without suppression instruction. Aggressive behavior was also more pronounced after suppression compared to a non-suppression group (behavioral rebound effect). The present results are discussed in the realm of goal-system theory and of other fields in aggression research like (triggered) displaced aggression
Bicyclic azoalkanes as probes and sensors in supramolecular chemistry
No full textThis thesis is focused on the investigation of the complexation of several bicyclic azoalkanes by cyclodextrins and calixarenes, selected as models of host molecules. The distinguished characteristics, such as water-solubility, spherical shape, microenvironmental sensitivity, and most importantly, the extremely long-lived fluorescence of the singlet excited-state of the 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), and its homologues and derivatives make azoalkanes suitable to be used as guests and molecular probes in supramolecular chemistry. Regarding potential applications, azoalkanes are very useful in the study of solution structures of inclusion complexes, chiral resolution, the kinetics of diastereomeric supramolecular association, the design of chemical sensors, and as enzyme mimics
Radical scavenging behavior of biogenic amines
No full textBiogenic amines are amino acid derived molecules with special functions in the vertebrate organism. They are often responsible for signal transmission, energy transfers, or redox-reactions. A special group of biogenic amines are indoleamines, including the well known “hormone of the darkness” melatonin, a substance, which regulates among other things seasonal mating behavior and diurnal rhythms in vertebrates. Serotonin is also an indoleamine, known as essential neurotransmitter. 5-hydroxytryptophan is the precursor of melatonin and serotonin and therefore as well structurally related to the group of indoleamines. Another type of biogenic amines is dopamine, belonging to the group of catecholamines as precursor of epinephrine and norepinephrine. All above mentioned substances contain carbon rings in their molecular structure, whereas the following biogenic amines are all neurotransmitters and molecules with chain character: acetylcholine, gamma-aminobutyric acid (GABA) and Lglutamic acid are all essential neurotransmitters working in the peripheral and in the central nervous system.
The above mentioned neurohormones and neurotransmitters were examined in two luminol chemiluminescence (CL) systems, especially developed to measure the hydroxyl radical scavenging ability of various substances. The potential hydroxyl radical scavenging ability of the neurohormone melatonin, 5-hydroxytryptophan, reduced glutathione and vitamin C were investigated in the Flow-CL-system, developed for a fast determination of the hydroxyl radical scavenging ability of measured substances, whereas all other neurotransmitters were tested in the Stationary-CL-system, which allowed more sensitive measurements
When refusal-goals turn into acquiescence behavior. Gender differences following refusal priming - a goal systems account
No full textThe aim of the current experiments was to enhance the understanding of automatic self-regulation processes facilitating the pursuit of high-priority goals acquired through socialization, which in the present proposal refers to goals of interdependence and independence. More specifically, we assume that a) in Western societies of today, due to gender-typed enculturation practices, women are more likely to strive for interdependence, whereas men are more likely to strive for independence (Cross & Madson, 1997); b) refusal-behavior is consistent with an independent self-construal but may threaten an interdependent self-construal (e.g., Adachi, 1997); c) therefore, preconscious activation of a refusal-goal should increase the accessibility of an independent self-construal in men but an interdependent self-construal in women (Fishbach, Friedman, & Kruglanski, 2003); and, finally, d) these differences in self-construal are expected to influence judgments and cognitive thinking style (Kühnen, Hannover, & Schubert, 2001) in a manner that facilitates goal attainment. In five studies, we tested the core assumptions of this model. As predicted we found gender differences in self-categorization, self-reported refusal behavior, semantic self-construal assessment, inclusion of others in the self-representation as well as in semantic free procedural tasks, suggesting that women become more interdependent and men more independent following the activation of a refusal-goal (Studies 1 - 4). Furthermore, we find evidence for the context-dependency of these effects (Study 4). Finally, Study 5 suggests that the observed gender differences can be accounted for by chronic differences in the goal systems of individuals. Implications for gender and cross-cultural research, assertiveness trainings in clinical and work settings, and goal-systems theory are discussed
Self-regulatory mechanisms in the evaluation of arts : the influence of regulatory focus and psychological distance on attitudes
No full textThe present project examines how self-regulatory mechanisms, namely regulatory foci (Higgins, 1997), affect attitudes towards conventional versus unconventional art. Conventional artworks (e.g., Mona Lisa by da Vinci) correspond to a traditional concept of art and are characterized by great artistic mastery. Unconventional artworks (e.g., Fountain by Duchamp), instead, are associated with a widening of the traditional concept of art, which makes it sometimes difficult to regard them as such. Based on findings from empirical aesthetics (Leder et al., 2004) and regulatory focus theory (Higgins, 1997) it is assumed that a prevention focus leads to more favorable attitudes towards conventional artworks compared to a promotion focus, whereas for unconventional artworks the reverse should be true. Given that a prevention focus bolsters a concrete processing mode and a promotion focus reinforces an abstract processing mode (Förster & Higgins, 2005), it is assumed that the influence of regulatory focus on aesthetic appreciation is due to a difference in processing modes. Consistent with our hypothesis we found the suggested interaction pattern for typicality (Study 1), behavioral (Study 2), and liking ratings (Study 3) and for objects other than art (Study 4). It was further demonstrated (Studies 3 and 4) that the influence of regulatory focus on affective as well as on behavioral measures is mediated by typicality estimates, thereby showing that regulatory foci affect aesthetic appreciation by their impact on categorical processing (Martindale, 1988). In Study 5 it was demonstrated that another manipulation for processing modes, namely psychological distance (Liberman & Trope, 1998), leads to the same results as varying regulatory focus, which supports the hypothesis that processing modes might have mediated the effects. The results are discussed in the context of empirical aesthetics and regulatory focus literature and future lines of research are elaborated