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Modulation der Zytokinproduktion durch Interaktionen von IRAK4 und p47phox mit den TLR-Signalwegen
(2015)
p47phox wird als ein in mehreren Strukturen involviertes Protein beschrieben, welches in seiner Funktion einen großen Einfluss auf das Immunsystem nehmen kann und damit zu schweren Erkrankungen führen kann. Wegen der Vielfalt der Interaktionen ist es schwierig die Effekte von p47phox einer bestimmten Wechselwirkung zuzuordnen. Dennoch ist es unserer Arbeitsgruppe gelungen eine negative Rückkopplung von p47phox auf die Produktion von IL-12p70 [1] festzustellen. Ausgehend von dieser Interaktion und der Phosphorylierung von p47phox durch IRAK4 [2], wurde daher in dieser Doktorarbeit der Zusammenhang einer Modulation der IL-12p70-Produktion durch IRAK4 näher untersucht.
The 3′ untranslated regions (3′ UTRs) of transcripts serve as important hubs for posttranscriptional gene expression regulation. Here, we find that the exonisation of intergenic Alu elements introduced new terminal exons and polyadenylation sites during human genome evolution. While Alu exonisation from introns has been described previously, we shed light on a novel mechanism to create alternative 3′ UTRs, thereby opening opportunities for differential posttranscriptional regulation. On the mechanistic level, we show that intergenic Alu exonisation can compete both with alternative splicing and polyadenylation in the upstream gene. Notably, the Alu-derived isoforms are often expressed in a tissue-specific manner, and the Alu-derived 3′ UTRs can alter mRNA stability. In summary, we demonstrate that intergenic elements can affect processing of preceding genes, and elucidate how intergenic Alu exonisation can contribute to tissue-specific posttranscriptional regulation by expanding the repertoire of 3′ UTRs.
This work proposes to employ the (bursty) GLO model from Bingmer et. al (2011) to model the occurrence of tropical cyclones. We develop a Bayesian framework to estimate the parameters of the model and, particularly, employ a Markov chain Monte Carlo algorithm. This also allows us to develop a forecasting framework for future events.
Moreover, we assess the default probability of an insurance company that is exposed to claims that occur according to a GLO process and show that the model is able to substantially improve actuarial risk management if events occur in oscillatory bursts.
Die diesjährige DVPW-Tagung Ende September sorgte für einige Unruhen in den Reihen der Vereinigung und darüber hinaus. Dabei geriet die eigentliche Tagung zum Thema „Vorsicht Sicherheit. Legitimationsprobleme der Ordnung von Sicherheit“ durch die Querelen auf der Mitgliederversammlung fast völlig aus dem Blick. Einen guten und umfassenden Tagungsbericht, um die inhaltliche Debatte nicht gänzlich in Vergessenheit geraten zu lassen, stellten die Kollegen des Theorieblogs zusammen (siehe hier ), live bloggten die Kollegen des Sicherheitsblogs (siehe hier)...
Mehr als 18 Milliarden Euro hat die Commerzbank im Zuge der Finanzkrise in Form von staatlichen Garantien, Kapitalspritzen oder Einlagen erhalten. Auch die Hypo Real Estate, die WestLB, die SachsenLB und die IKB profitierten von Stützungsmaßnahmen. Die EU genehmigte diese und andere staatlichen Hilfsmaßnahmen. Grundsätzlich sind staatliche Stützungsmaßnahmen jedoch als wirtschaftlicher Vorteil zu werten und damit zunächst eine verbotene Beihilfe. In seinem Working Paper betrachtet Tuschl die rechtlichen Grundlagen des EU-Beihilferechts und zeigt die teilweise differierende Praxis der EU-Kommission auf.
The Federal Reserve’s muddled mandate to attain simultaneously the incompatible goals of maximum employment and price stability invites short-term-oriented discretionary policymaking inconsistent with the systematic approach needed for monetary policy to contribute best to the economy over time. Fear of liftoff—the reluctance to start the process of policy normalization after the end of a recession—serves as an example. Causes of the problem are discussed, drawing on public choice and cognitive psychology perspectives. The Federal Reserve could adopt a framework that relies on a simple policy rule subject to periodic reviews and adaptation. Replacing meeting-by-meeting discretion with a simple policy rule would eschew discretion in favor of systematic policy. Periodic review of the rule would allow the Federal Reserve the flexibility to account for and occasionally adapt to the evolving understanding of the economy. Congressional legislation could guide the Federal Reserve in this direction. However the Federal Reserve may be best placed to select the simple rule and could embrace this improvement on its own, within its current mandate, with the publication of a simple rule along the lines of its statement of longer-run goals.
This paper investigates the effect of a change in informational environment of borrowers on the organizational design of bank lending. We use micro-data from a large multinational bank and exploit the sudden introduction of a credit registry, an information-sharing mechanism across banks, for a subset of borrowers. Using within borrower and loan officer variation in a difference-in-difference empirical design, we show that expansion of credit registry led to an improvement in allocation of credit to affected
borrowers. There was a concurrent change in the organizational structure of the bank that involved a dramatic increase in delegation of lending decisions of affected borrowers to loan officers. We also find a significant expansion in scope of activities of loan officers who deal primarily with affected borrowers, as well as of their superiors. There is suggestive evidence that larger banks in the economy were better able to implement similar changes as our bank. We argue that these patterns can be understood within the framework of incentive-based and information cost processing theories. Our findings could help rationalize why improvements in the information environment of borrowers may be altering the landscape of lending by moving decisions outside the boundaries of financial intermediaries.
This chapter outlines the conditions under which accounting-based smoothing can be beneficial for policyholders who hold with-profit or participating payout life annuities (PLAs). We use a realistically-calibrated model of PLAs to explore how alternative accounting techniques influence policyholder welfare as well as insurer profitability and stability. We find that accounting smoothing of participating life annuities is favorable to consumers and insurers, as it mitigates the impact of short-term volatility and enhances the utility of these long-term annuity contracts.
We investigate the determinants of firms’ implicit insurance to employees, using a difference-in-difference approach: we rely on differences between family and non-family firms to identify the supply of insurance, and exploit variation in unemployment insurance across and within countries to gauge workers’ demand for insurance. Using a firm-level panel from 41 countries, we find that family firms feature more stable employment, greater wage flexibility and lower labor cost than non-family ones. Employment stability in family firms is greater, and the wage discount larger, in countries with more generous public unemployment insurance: private and public provision of employment insurance are substitutes.
We propose a multivariate dynamic intensity peaks-over-threshold model to capture extreme events in a multivariate time series of returns. The random occurrence of extreme events exceeding a threshold is modeled by means of a multivariate dynamic intensity model allowing for feedback effects between the individual processes. We propose alternative specifications of the multivariate intensity process using autoregressive conditional intensity and Hawkes-type specifications. Likewise, temporal clustering of the size of exceedances is captured by an autoregressive multiplicative error model based on a generalized Pareto distribution. We allow for spillovers between both the intensity processes and the process of marks. The model is applied to jointly model extreme returns in the daily returns of three major stock indexes. We find strong empirical support for a temporal clustering of both the occurrence of extremes and the size of exceedances. Moreover, significant feedback effects between both types of processes are observed. Backtesting Value-at-Risk (VaR) and Expected Shortfall (ES) forecasts show that the proposed model does not only produce a good in-sample fit but also reliable out-of-sample predictions. We show that the inclusion of temporal clustering of the size of exceedances and feedback with the intensity thereof results in better forecasts of VaR and ES.
Expectations of Sterling returning to Gold have been disregarded in empirical work on the US dollar – Sterling exchange rate in the early 1920s. We incorporate such considerations in a PPP model of the exchange rate, letting the probability of a return to gold follow a logistic function. We draw several conclusions: (i) the PPP model works well from spring 1919 to spring 1925; (ii) wholesale prices outperform consumer prices; (iii) allowing for a return to gold leads to a higher speed of adjustment of the exchange rate to PPP; (iv) interest rate differentials and the relative monetary base are crucial determinants of the expected return to gold; (v) the probability of a return to Gold peaked at about 72% in late 1924 and but fell to about 60% in early 1925; and (vi) our preferred model does not support the Keynes’ view that Sterling was overvalued after the return to gold.
Since the 1970s, the overarching view in the literature has been that a Phillips curve relationship did not exist in Ireland prior to the 1979 exchange rate break with Sterling. It was argued that, as a small open economy, prices were determined externally. To test this relationship, we study the determination of inflation between 1926 and 2012, a longer sample period than any previously used. We find that the difference between unemployment and the NAIRU is a significant determinant of inflation both in the full sample and in the subsamples spanning the periods before and after the Sterling parity link.
In this paper we assemble an annual data set on broad and narrow money, prices, real economic activity and interest rates in Ireland from a variety of sources for the period 1933-2012. We discuss in detail how the data set is constructed and what assumptions we have made to do so. Furthermore, we estimate a simple SVAR model to provide some empirical evidence on the behaviour of these time series. Money supply shocks appear to be the most important drivers of both money and prices. Interest rate shocks, which capture monetary policy, play an important role driving output and, of course, interest rates. The GDP shocks, which raise prices, seem of less importance.
We model education as an investment in human capital that, like other investments, is appropriately evaluated in a framework that accounts for risk as well as return. In contrast to dominant wage-premia approach to calculating the returns to education, but which implicitly ignores risk, we evaluate the returns by treating the value of human capital as the price of a non-tradable risky asset. We do so using a lifecycle framework that incorporates risk preferences and earnings risk, as well as a progressive income tax and social insurance system. Our baseline estimate is that a college degree provides a $440K dollar increase in annual certainty-equivalent consumption. Although significantly smaller than traditional estimates of the value of education, these returns are still large enough to offset both the direct and indirect cost of college education for a large range of plausible preference parameters. Importantly, however, we find that accounting for risk reverses the finding from the education wage-premia literature regarding the trends in the returns to education. In particular, we find that the risk-adjusted gains from college completion actually decreased rather than increased in the recent period. Overall, our results show the importance of earnings risks in assessing the value of education.
We examine how U.S. monetary policy affects the international activities of U.S. Banks. We access a rarely studied US bank‐level dataset to assess at a quarterly frequency how changes in the U.S. Federal funds rate (before the crisis) and quantitative easing (after the onset of the crisis) affects changes in cross‐border claims by U.S. banks across countries, maturities and sectors, and also affects changes in claims by their foreign affiliates. We find robust evidence consistent with the existence of a potent global bank lending channel. In response to changes in U.S. monetary conditions, U.S. banks strongly adjust their cross‐border claims in both the pre and post‐crisis period. However, we also find that U.S. bank affiliate claims respond mainly to host country monetary conditions.
No. And not only for the reason you think. In a world with multiple inefficiencies the single policy tool the central bank has control over will not undo all inefficiencies; this is well understood. We argue that the world is better characterized by multiple inefficiencies and multiple policy makers with various objectives. Asking the policy question only in terms of optimal monetary policy effectively turns the central bank into the residual claimant of all policy and gives the other policymakers a free hand in pursuing their own goals. This further worsens the tradeoffs faced by the central bank. The optimal monetary policy literature and the optimal simple rules often labeled flexible inflation targeting assign all of the cyclical policymaking duties to central banks. This distorts the policy discussion and narrows the policy choices to a suboptimal set. We highlight this issue and call for a broader thinking of optimal policies.
We examine firms’ simultaneous choice of investment, debt financing and liquidity in a large sample of US corporates between 1980 and 2014. We partition the sample according to the firms’ financial constraints and their needs to hedge against future shortfalls in operating income. In contrast to earlier work, our joint estimation approach shows that cash flows affect the corporate decisions of unconstrained firms more strongly than those of constrained firms. Investment-cash flow sensitivities are particularly intense for unconstrained firms with high hedging needs. Investment opportunities (as proxied by Q), however, play a larger role for constrained firms with the effects being strongest in case of low hedging needs. Interestingly, constrained firms with low hedging needs are found to employ more debt to finance their investment opportunities and build up significant cash holdings at the same time. Our results hence indicate overinvestment behavior for unconstrained firms but no underinvestment for constrained firms if they have low hedging needs.
We develop a dynamic recursive model where political and economic decisions interact, to study how excessive debt-GDP ratios affect political sustainability of prudent fiscal policies. Rent seeking groups make political decisions – to cooperate (or not) – on the allocation of fiscal budgets (including rents) and issuance of sovereign debt. A classic commons problem triggers collective fiscal impatience and excessive debt issuing, leading to a vicious circle of high borrowing costs and sovereign default. We analytically characterize debt-GDP thresholds that foster cooperation among rent seeking groups and avoid default. Our analysis and application helps in understanding the politico-economic sustainability of sovereign rescues, emphasizing the need for fiscal targets and possible debt haircuts. We provide a calibrated example that quantifies the threshold debt-GDP ratio at 137%, remarkably close to the target set for private sector involvement in the case of Greece.
In 2000 Italy replaced its traditional system of severance pay for public employees with a new system. Under the old regime, severance pay was proportional to the final salary before retirement; under the new regime it is proportional to lifetime earnings. This reform entails substantial losses for future generations of public employees, in the range of €20,000-30,000, depending on seniority. Using a difference-in-difference framework, we estimate the impact of this unanticipated change in lifetime resources, on the current consumption and wealth accumulation of employees affected by the reform. In line with theoretical simulations, we find that each euro reduction in severance pay reduces the average propensity to consume by 3 cents and increases the wealth-income ratio by 0.32. The response is stronger for younger workers and for households where both spouses are public sector employees.
We examine the inter-linkages between financial factors and real economic activity. We review the main theoretical approaches that allow financial frictions to be embedded into general equilibrium models. We outline, from a policy perspective, the most recent empirical papers focusing on the propagation of exogenous shocks to the economy, with a particular emphasis on works dealing with time variation of parameters and other types of nonlinearities. We then present an application to the analysis of the changing transmission of financial shocks in the euro area. Results show that the effects of a financial shock are time-varying and contingent on the state of the economy. They are of negligible importance in normal times but they greatly matter in conditions of stress.
In many European countries poverty migration and its impact on the European continent are currently widely discussed topics. Many seem to forget about grave migration problems taking place in Asia, where in Hong Kong, for example, the working and living conditions for approximately 320,000 foreign domestic workers (mostly women) are often intolerable.
With only a 2.6 Å resolution laboratory powder diffraction pattern of the θ phase of Pigment Yellow 181 (P.Y. 181) available, crystal-structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom, was determined in three stages by a combination of simulated annealing, partial Rietveld refinement with dummy atoms replacing the solvent molecules and further simulated annealing. The θ phase not being of commercial interest, additional experiments were not economically feasible and additional dispersion-corrected density functional theory (DFT-D) calculations were employed to confirm the correctness of the crystal structure. After the correctness of the structure had been ascertained, the bond lengths and valence angles from the DFT-D minimized crystal structure were fed back into the Rietveld refinement as geometrical restraints (‘polymorph-dependent restraints’) to further improve the details of the crystal structure; the positions of the H atoms were also taken from the DFT-D calculations. The final crystal structure is a layered structure with an elaborate network of hydrogen bonds.
Background: Due to the large amount of data produced by advanced microscopy, automated image analysis is crucial in modern biology. Most applications require reliable cell nuclei segmentation. However, in many biological specimens cell nuclei are densely packed and appear to touch one another in the images. Therefore, a major difficulty of three-dimensional cell nuclei segmentation is the decomposition of cell nuclei that apparently touch each other. Current methods are highly adapted to a certain biological specimen or a specific microscope. They do not ensure similarly accurate segmentation performance, i.e. their robustness for different datasets is not guaranteed. Hence, these methods require elaborate adjustments to each dataset.
Results: We present an advanced three-dimensional cell nuclei segmentation algorithm that is accurate and robust. Our approach combines local adaptive pre-processing with decomposition based on Lines-of-Sight (LoS) to separate apparently touching cell nuclei into approximately convex parts. We demonstrate the superior performance of our algorithm using data from different specimens recorded with different microscopes. The three-dimensional images were recorded with confocal and light sheet-based fluorescence microscopes. The specimens are an early mouse embryo and two different cellular spheroids. We compared the segmentation accuracy of our algorithm with ground truth data for the test images and results from state-of-the-art methods. The analysis shows that our method is accurate throughout all test datasets (mean F-measure: 91%) whereas the other methods each failed for at least one dataset (F-measure≤69%). Furthermore, nuclei volume measurements are improved for LoS decomposition. The state-of-the-art methods required laborious adjustments of parameter values to achieve these results. Our LoS algorithm did not require parameter value adjustments. The accurate performance was achieved with one fixed set of parameter values.
Conclusion: We developed a novel and fully automated three-dimensional cell nuclei segmentation method incorporating LoS decomposition. LoS are easily accessible features that ensure correct splitting of apparently touching cell nuclei independent of their shape, size or intensity. Our method showed superior performance compared to state-of-the-art methods, performing accurately for a variety of test images. Hence, our LoS approach can be readily applied to quantitative evaluation in drug testing, developmental and cell biology.
Snake bite envenoming often results in disability or death of breadwinners of poor families in the rural tropics and the subtropics of Nepal. Identification of the medically relevant snake species, circumstances of venomous snake bites, prehospital care of their bites and human responses to snakes and snake bite is, therefore, crucial to enable victims or first aider to select the appropriate first aid measures, physicians to anticipate complications and to use appropriate treatment protocols as well as the local community to implement prevention strategies. Inadequate educational gaps exist in Nepal and hinder identification of snakes involved in bites. To fill this gap, I aim to provide an evidence-based list of medically relevant snake species. Snake specimens brought by patients bitten or their attendants from the tropical and subtropical regions in southeastern, southcentral, and southwestern Nepal to snake bite treatment centres over a period from 2010 through 2014, were taxonomically identified and medical records of envenoming were evaluated.
In Nepal, the epidemiology of snake bite is poorly known. Here I describe the ecological circumstances of proven krait (Bungarus spp.) and Russell´s Viper (Daboia russelii) bites to elucidate and examine, whether environmental circumstances or human behaviour contributed to envenoming. In a cross-sectional study, data about prehospital care, environmental circumstances of 46 krait and 10 Russell´s Viper bites were evaluated. Patients were interviewed using structured interview forms. Snake bite prone communities were surveyed to test people´s knowledge on snakes and their attitude towards venomous snakes in general.
Of 349 snakes involved in bites, 199 (57%) specimens were found to be medically relevant venomous snakes that included 11 species belonging to six genera and two families. Among them, Naja naja (n = 76, 22%), Bungarus caeruleus (n = 65, 19%) and Trimeresusurs albolabris (n = 10, 3%) were the most widely distributed snakes. Daboia russelii (n = 10, 3%) was found to be restricted to the southwestern part of Nepal. For B. walli, a previously poorly known species, 13 voucher specimens represent the first country records of this species as well as the first documented cases of involvement in snake bite envenoming by this species in Nepal.
Numerous snake bites (33%) occurred at night, during the rainy season, and are mainly due to Bungarus species, particularly B. caeruleus. Bites of cobras and Russell’s Vipers are a risk at daytime. Evaluation of data regarding the place where the bite happened, indicates that the snake bite risks appear to be as high in residential areas, in and around houses, as in rural areas. In cases of kraits (n = 46), 61% of the bites occurred while the victim was sleeping indoors, those of Russell´s Vipers mainly during agricultural activities in the fields. Analysis of socio-demographic data revealed that both krait and viper bites predominantly affected farmers or their family members. However, snake bites involved also people of higher socio-economic status, which suggests that it is not a health problem of poor people only living in the rural areas of Nepal.
A small number of snake bite victims (n = 7) sought help from traditional healers, but most patients went to hospitals for medical treatment using motorbikes (65%) or were transferred by ambulance cars (22%). As a first aid measure, most patients (78%) had used a tourniquet, which is of doubtful value and has often severe sequelae, instead of applying the WHO recommended pressure immobilisation bandage or local compression pad. The overall case fatality rate was calculated to be 10%, but up to 17% in cases of Bungarus spp. bites.
Rural community people were found to be extremely afraid of snakes, a major reason for indiscriminate killing of even harmless snakes, e.g., Lycodon aulicus, which were wrongly considered to be venomous. This is mainly due to the poor knowledge on snakes in general and on their role in providing ecological services, which may eventually lead to a decline in snake populations and even the extinction of rare species.
The results of the present study strongly emphasize that snake bite is an important public health issue in Nepal. There is an urgent need to improve the knowledge of people on snakes and to try changing their attitudes towards these reptiles, in addition to documenting the biodiversity and distribution of medically relevant snakes, the epidemiology and circumstances of their bites. Avoiding high-risk behaviour (e.g., killing of snakes), using screened doors and windows are some of the suggested measures preventing snake bite. Early and accurate identification of the snakes involved should help physicians to apply timely treatment, eventually referring the patient to the appropriate hospital. This also has important implications in developing public health and conservation strategies, to the benefit of the people of Nepal.
Demographic change belongs to the mega-trends of the 20th and the 21st century. The ongoing aging process in major industrialized countries gives rise to the relative scarcity of raw labor and the relative abundance of physical capital. Standard macroeconomic models suggest that this depresses asset returns and increases wages which, in turn, provides incentives for more human capital accumulation. This thesis quantifies the macroeconomic effects of demographic change and reveals the importance of human capital adjustments for price and welfare effects within and across generations. Chapter 1 investigates the distributions of income, skills, and welfare in the German economy along the inter- and the intra-generational dimension. It shows that demographic change leads to a more capital- and skill-intensive economy and that high-school households loose compared to college households in terms of welfare. Chapter 2 disentangles the effect of demographic change on returns to risk-free and risky assets in the U.S. and measures the net effect on the equity premium. It shows that both returns decline while the equity premium increases slightly. Endogenous human capital adjustments are crucial for relatively small effects. Chapter 3 develops a method for computing transitional dynamics in heterogeneous agent models with aggregate risk if these transitions are induced by exogenous deterministic dynamics such as demographic change. The application of the method to a simple illustrative example shows a large reduction in total computing time while approximation errors are small.
In conclusion our data show, that Flightless I function is essential for striated muscle development in zebrafish. Myofibrillar bundling and focal adhesion formation represent the basis for this development, and are ultimately a prerequisite for cardiac trabeculation. Future analysis of Actin polymerization in trabeculation will provide addition knowledge about the sensitivity of the developing and adult heart to a disequilibrium in F-actin versus G-actin availability.
In this study we found a novel ErbB2-dependent cardiomyocyte maturation process which affects both cardiac chambers. It will be of great interest to further study the nature of the Memo1-GFP cell-cell junctions and other junction proteins in order to unravel the significance of this maturation process for heart development.
Interestingly we found, that memo1bns4 homozygous mutant animals, which we generated with CRISPR/Cas9 technology, develop indistinguishable from siblings, suggesting that zygotic memo1 expression is dispensable for zebrafish development. Future studies will address the question if maternal zygotic memo1bns4 mutants will develop a heart or vascular phenotype as reported form Memo1 knockout mice or as observed in memo1 morphants in this study.
In cultured C2 mouse skeletal muscle cells the Golgi-apparatus relocalizes dependent on centrosomal proteins and independent of microtubules. We describe here that zebrafish cardiomyocytes have a similar Golgi-complex distribution suggesting a similar differentiation-dependent reorganization. This striated muscle specific, fragmented Golgi distribution might be an advantage for these cells in order to shuttle vesicles through the densely packed sarcomere structures. Future studies could address the timing of the Golgi-reorganization in cardiomyocytes during development and possibly use this Golgi-zebrafish line as a tool to study cardiomyocyte maturation in disease models and in heart regeneration.
The knowledge of three-dimensional structures of biomolecules is fundamental for the understanding of their function. Nuclear magnetic resonance (NMR) spectroscopy represents besides X-ray crystallography one of the two most widely used techniques to study macromolecules at atomic resolution. Its application has long been a laborious task that could take months and required the expertise of an experienced scientist, however, owing to the tremendous effort that has been put into the development of respective computer algorithms, structure determination by NMR spectroscopy of small- to medium sized proteins is nowadays routinely performed. CYANA is one widely used software package, which combines the majority of individual steps towards a three-dimensional structure. The most common application of the program, however, restricts to the combined automated NOE assignment and structure calculation based on NOESY peak lists and an existing chemical shift assignment. Completely automated structure determination starting from NMR spectra is to date technically possible with CYANA, however, not yet routinely applied. In order to achieve this long-term goal, the individual steps need to become more robust with regard to data imperfections such as peak overlap, spectral artifacts or a limited amount of NMR data. The work presented in this thesis should be placed within the context of increasing the reliability and improving the accuracy of structures determined by CYANA on the basis of solution- as well as solid-state NMR data.
The chapter “Systematic evaluation of combined automated NOE assignment and structure calculation with CYANA” comprises an extensive study on the robustness of the combined automated NOE assignment and structure calculation algorithm based on experimental solution NMR data sets that were modified in multiple ways to mimic different kinds of data imperfections. The results show that the algorithm is remarkably robust with regard to imperfections of the NOESY peak lists and the chemical shift tolerances but susceptible to lacking or erroneous resonance assignments, in particular for nuclei that are involved in many NOESY cross peaks.
In the chapter “Peakmatch – A simple and robust tool for peaklist matching” a method to achieve self-consistency of the chemical shift referencing among a set of peak lists is presented. The Peakmatch algorithm matches a set of peak lists to a specified reference peak list, neither of which have to be assigned, by optimizing an assignment-free match-score function. The algorithm has been extensively tested on the basis of experimental NMR data sets of five different proteins. The results show that peak lists from many different types of spectra can be matched reliably as long as they contain at least two corresponding dimensions.
NMR structures are represented by bundles of conformers whose spread indicates the precision of the atomic coordinates. However, there is as yet no reliable measure of structural accuracy, i.e. how close NMR conformers are to the “true” structure. Instead, the precision of structure bundles is widely (mis)interpreted as a measure of structural quality. Attempts to increase the precision thus often yield tight structure bundles where the precision overestimates the accuracy. To overcome this problem, the chapter “Increased reliability of NMR protein structures by consensus structure bundles” introduces a new protocol for NMR structure determination with the software package CYANA that produces bundles of conformers with a realistic precision that is throughout a large number of test data sets a much better estimate of the structural accuracy than the precision of conventional structure bundles.
Solid-state NMR is a powerful technique to study molecules which are not amenable to either solution NMR or X-ray crystallography. Despite the reporting of individual atomic resolution structures of membrane proteins and amyloid fibrils based on solid-state NMR data, the application is far from routine. One major obstacle that hinders structure determination by solid-state NMR is the overall lower quality of the solid-state NMR spectra. It is therefore necessary to increase the robustness of the computer algorithms in order to improve the results when using lower quality solid-state NMR spectra. The chapter “Structure calculations of the model protein GB1 from solid-state NMR data” presents structure calculations on the basis of a set of two-dimensional solid-state NMR experiments of the model protein GB1. The most important result obtained from these test calculations is that the limitation of structural accuracy can be attributed to inaccurate distance information resulting from the limited correlation between peak intensities and distance, which is especially severe in spin diffusion-based solid-state NMR experiments.
The chapter “Full relaxation matrix-based correction of relayed polarization transfer for solid-state NMR structure calculation” therefore introduces a method which corrects experimental peak intensities for spin diffusion in order to improve the distance information from solid-state NMR spectra. The results show that the structural accuracy can be significantly improved when using the corrected distance information, however, strongly dependent on the preliminary structural model that is required as input for the method.
Stechmücken (Dipteren: Culicidae) sind weltweit mit über 3500 Arten und mit Ausnahme der arktischen Regionen ubiquitär vertreten. Die medizinische Relevanz dieser Tiergruppe, begründet durch die hämatophage Lebensweise der Weibchen, erschloss sich bereits Ende des 19. Jh. und hat bis heute Bestand. Jedes Jahr sterben rund 600.000 Menschen an den Folgen der Malaria und fast 100 Mio. Menschen infizieren sich mit dem Denguefieber. Zwar beziehen sich diese Zahlen fast ausschließlich auf die Entwicklungsländer, aber im Zuge des Klimawandels und des immer stärkeren Welthandels kommt es auch in Europa und den USA immer wieder zu Ausbrüchen vorher nicht relevanter Krankheiten. So hat sich das West-Nil- Virus seit 1999 in Nordamerika rasant verbreitet. Im Jahr 2013 gab es dort rund 2500 Fälle, von denen 119 zum Tod führten. In Europa traten hingegen Krankheiten wie das Chikungunyafieber (Italien 2007) oder das Denguefieber (Frankreich 2010/2013) auf. Die Gründe für diese Ausbrüche sind vor allem in der Einschleppung neuer Vektorspezies und Krankheitserreger sowie in den veränderten Wirtspräferenzen einheimischer Stechmückenarten zu suchen. Das Wissen um das Vektorpotential der in Deutschland heimischen Stechmücken konnte vor allem durch die seit 2009 initiierten Monitoring-Programme stetig erweitert werden. Auch die Veränderung der heimischen Fauna durch invasive Arten wie Ochlerotatus japonicus japonicus oder Aedes albopictus wird intensiv erforscht. Dennoch ist hinsichtlich der Biologie, Ökologie sowie Genetik vieler Arten noch immer wenig bekannt.
Die vorliegende Dissertation, welche auf Basis von vier (ISI-) Einzelpublikationen kumulativ angefertigt wurde, beschäftigte sich mit der Analyse der genetischen Variabilität sowie der Zoogeographie der untersuchten Arten und der Etablierung einer schnellen und kostengünstigen Methode zur Artdiagnostik. Besonderes Augenmerk wurde bei den Analysen auf die beiden heimischen Arten Culex pipiens und Culex torrentium sowie die invasive Art Ochlerotatus japonicus japonicus gelegt. Ziel war es, die noch bestehenden Wissenslücken zu füllen, um zukünftige Monitoring-Programme besser koordinieren sowie Analysen zur Vektorkompetenz und Genetik dieser Arten gezielter durchführen zu können.
Es konnte gezeigt werden, dass Cx. pipiens und Cx. torrentium deutliche Unterschiede in ihren Populationsstrukturen aufwiesen welche auf verschiedene evolutive Prozesse hindeuten. Die geringere genetische Variabilität in Cx. pipiens lässt auf positive Selektion durch z.B. Insektizidresistenz im Zuge durchgeführter Bekämpfungsmaßnahmen oder die Infektion mit Wolbachien schließen. Die analysierte Populationsstruktur von Cx. torrentium spricht hingegen für eine geringe Ausbreitung, wodurch der genetische Austausch reduziert wurde und so die untersuchten Populationen genetisch stärker voneinander abwichen. Des Weiteren ließen die Analysen des Cytochrom c Oxidase Untereinheit 1-Fragmentes (cox1) Rückschlüsse auf die Zoogeographie dieser Arten in Deutschland zu - wobei beide Arten über das Untersuchungsgebiet verteilt waren, Cx. torrentium jedoch in den neuen Bundesländern weniger häufig nachgewiesen wurde als in den alten und eine geringere gefangene Individuenzahl aufwies. Basierend auf der ökologischen Nischenmodellierung konnten potentiell neue Verbreitungsgebiete für die Art Ochlerotatus japonicus japonicus identifiziert werden. Als klimatisch besonders günstig zeigten sich dabei Südhessen, das Saarland sowie nördliche Teile Nordrhein-Westfalens. Mit Hilfe der etablierten Methode der direct-PCR wird in Zukunft eine schnellere und kostengünstigere Identifizierung von Stechmücken erfolgen können, welche aufgrund bestimmungsrelevanter Merkmale nicht mehr morphologisch zu identifizieren sind.
Um das Wissen über die Stechmücken in Deutschland fortlaufend zu intensivieren, ist sowohl das Weiterführen der Monitoring-Programme als auch die molekularbiologische Aufarbeitung der Proben nötig. Durch die Anwendung neuer Techniken und weiterer molekularer Marker wird es möglich sein, weitere Krankheitserreger sowie genetische Besonderheiten der heimischen Stechmückenfauna nachzuweisen. Aber auch die Überwachung invasiver Stechmückenarten durch die Modellierung potentieller Verbreitungsgebiete und die Anwendung molekularbiologischer Analysemethoden zum Detektieren der Arten und möglicher Krankheitserreger wird ein wichtiger Bestandteil der weiteren Forschung sein.
Die Parkinson Erkrankung ist die zweithäufigste neurodegenerative Erkrankung in industrialisierten Ländern. Die charakteristischen Symptome sind schwere Beeinträchtigungen des Bewegungsablaufes welche auf den Verlust dopaminerger Neurone der Substantia nigra und der damit einhergehenden Reduktion des striatalen Dopamin Gehaltes zurückzuführen sind. Alpha-Synuklein (SNCA) ist ein Protein welches zum einen mit sporadischen aber auch mit idiopathischen Erkrankungen assoziiert ist. Mutationen welche einen Funktionsgewinn von SNCA zur Folge haben konnten mit autosomal dominanten Varianten der Parkinson Erkrankung assoziiert werden und genetische Veränderungen an beiden Genenden agieren als Risikofaktor für sporadische Formen der Erkrankung. Des Weiteren wird SNCA als Hauptbestandteil der Lewy Körperchen gefunden, einem pathologischen Kennzeichen der parkinsonschen Erkrankung. Die charakteristischen Bewegungsstörungen können mittels L-DOPA, einer metabolischen Vorstufe von Dopamin, behandelt werden. Neben dem enorm positiven Effekt auf die Bewegungsstörungen, geht die Behandlung mit L-DOPA jedoch auch mit ernsten Nebenwirkungen einher, welche als Levodopa induzierte Dyskinesien (LID) beschrieben werden.
Ziel der Arbeit war die Analyse von Effekten eines SNCA Funktionsgewinns sowie des Pink1 Funktionsverlustes auf molekulare Signalwege der synaptischen Plastizität unter Verwendung dreier PD Mausmodelle (A53T-SNCA überexprimierendes Modell (PrPmtA), Pink1KO Modell sowie A53T-SNCA + Pink1KO Doppelmutante (DM)). Es wurden Kandidatengene welche eine Rolle für synaptische Plastizität spielen in 6 Monate alten Mäusen aller drei PD Mauslinien untersucht. Die Analyse von PrPmtA zeigte erhöhte mRNA Spiegel von Glutamatrezeptor-Untereinheiten und von Kandidatengenen welche eine Rolle bei der synaptischen Signalweiterleitung spielen, sowie reduzierte mRNA Spiegel von IEGs und Transkriptionsfaktoren. Die Analyse der DM zeigte nur geringe Expressionsänderungen der Glutamatrezeptor-Untereinheiten und die Analyse von IEGs und Transkriptionsfaktoren zeigte erneut reduziert mRNA Spiege. In Pink1KO Tieren konnten nur minimale Expressionsveränderungen der Kandidatengene gefunden werden, was den Schluss zulässt, dass die zuvor beschriebenen Expressionsveränderungen in PrPmtA und DM Mäusen eindeutig auf den SNCA Funktionsgewinn zurückzuführen sind. Um frühe Effekte des SNCA Funktionsgewinns zu studieren wurde die Analyse auf 3 Monate alte PrPmtA Mäuse ausgeweitet. Diese ergab, Expressionsveränderungen für Homer1, cFos, NOR1, Nurr1 und Nur77.
In einem weiteren Versuchsansatz wurde die Auswirkung des SNCA Funktionsgewinns auf das Verhalten sowie auf molekulare Parameter nach Apomorphin Behandlung analysiert. Die Analyse ergab ein erhöhtes Niveau an unwillkürlichen Bewegungsmustern mit stereotypen und dystonischen Eigenschaften in PrPmtA im Vergleich zu Wildtypen (wt). Die molekulare Analyse von striatalem Gewebe wurde zu zwei Zeitpunkten durchgeführt, 30 min nach Apomorphin Injektion und 100 min nach Injektion. Die Analyse von striatalem Gewebe welches zum Zeitpunkt 30 min nach Injektion entnommen wurde ergab eine erhöhte Apomorphin abhängige Phosphorylierung von ERK1/2, sowie eine erhöhte Apomorphin abhängige Expression von Dusp1, Dusp6 und cFos in transgenen und wt Tieren. Genotyp abhängige Unterschiede ergaben sich für cFos, welches signifikant höher in PrPmtA induziert wurde. 100 min nach Apomorphin Injektion ergab die gleiche Analyse eine erhöhte Apomorphin abhängige Phosphorylierung von ERK1 und eine erhöhte Apomorphin abhängige Expression von Dusp1, Dusp6, cFos und Nur77 in PrPmtA im Vergleich zu wt. Die Daten unterstreichen die fundamentale Rolle von SNCA auf die Neurotransmission und synaptische Plastizität und zeigen auf, dass PrPmtA ein zuverlässiges Modell für die Analyse von präsynaptischer Dysfunktion in Frühstadien der Parkinson Erkrankung darstellt.
Der letzte Versuchsansatz stellt die Charakterisierung des DM-Mausmodells welches sich durch einen starken Phänotyp auszeichnet, sowie die Analyse des Pink1 Effektes auf die SNCA induzierte Neurotoxizität dar. DM-Tiere zeigen deutlich reduzierte Spontanmotorik im Alter von 3 Monaten sowie einer progressiven Lähmung der Hinterläufe, was Anlass zu einer immunhistologischen Charakterisierung mittels Schnitten des Gehirns und Rückenmarks gab. Die histologische Analyse zeigte pSer129-SNCA, p62/SQSTM1 und Ubiquitin positive Aggregate innerhalb der grauen Substanz des Rückenmarks sowie innerhalb einer neuronalen Zellpopulation welche dorsal der Substantia nigra angeordnet ist. Das histologische Erscheinungsbild wurde spezifisch in gelähmten DM-Tieren gefunden und nicht in Einzelmutanten oder DM-Tieren ohne Lähmung. Dieses Modell stellt ein wertvolles Instrument für die Identifizierung von pathologischen Mechanismen und Signalkaskaden welche beiden Parkinson relevanten Genen gemeinsam sind, dar.
This work deals with so-called wh-determination. The notion of D-linking (Discourse-linking) is used to uncover and explain properties of constructions involving wh-determiners. The central claim is that there are two types of wh-determination: Token-whs and Kind-whs. These two forms of wh-determination trigger different syntactic effects. Three structural triggers for the syntactic effects exhibited by D-linked wh-phrases (DWH) are discussed. DWH are argued to be instances of Token-whs since triggers for the syntactic effects of D-linking are identical to the once for the token-reading of a wh-phrase.
In chapter 2, which-phrases are shown to be canonical DWH with a special syntax labelled DL-S(yntax). The five most prominent and frequent DL-S effects are the absence of superiority-effects with DWH, the ability of DWH to be extracted out of weak islands, the fact that DWH licence resumptive elements, the obviation of WCO effects by DWH, and the possibility for DWH to stay in-situ. The syntax of Token-whs and Kind-whs are compared. It is demonstrated that regardless of the actual form of the wh-determiner, there are only these two types of wh-determination. These data support the idea that the DL-S effects observable with DWH are triggered by structural properties of the wh-determiners heading DWH.
In chapter 3, it is demonstrated that although presuppositions projected by the Nominal Restrictor are important for triggering DL-I(nterpretation), they do not directly influence DL-S. The ambiguity of Amount-whs is also examined and the conclusion reached is that there are two #P projections: A NumP and a CardP. The dissertation proceeds with the structurally represented notions of definiteness and specificity and examines how these can help capturing the wh-determiner typology proposed. The idea that D-linking can be explained by recourse to topicality is discussed in detail. Empirical evidence is provided for the existence of wh-topics in general and for the claim that many DWH can be construed as wh-topics.
In chapter 4, the general pattern on which wh-pronouns are built are examined, and it is argued that the results bear directly on the topic of this thesis since wh-determiners are universally derived from pronouns. Wh-pronouns are diachronically built out of an element indicating the function of the proform (wh-morpheme), and an element denoting the range of the proform (Range Restrictor). Among other things, it is argued that the wh-morpheme does not mark interrogativity, leading to the adoption of a version of Q-theory. It is also briefly discussed whether the results are compatible with the hypothesis that wh-determiner phrases are Small Clauses. One claim is that all wh-pronouns are fossilized interrogative sentences, lending further support to the parallelism between sentential and nominal structures. It is then argued that Morphological Restrictors can be subdivided into Formal Features and Functional Nouns (and that elements which can become Functional Nouns are taken from the pool of Basic Ontological Categories). The question answered is how these elements synchronically contribute to the meaning of the wh-determiners. After examining the role of the Nominal Restrictor to the syntax of wh-determiners, the thesis continues investigating how Nominal Restrictor are related to Functional Nouns. Finally, the discussion expands to the structural correlates for DL-S effects. It is demonstrated how the results can formally be applied to wh-split constructions in order to explain differences between empty categories. Then, the results of the section on partitivity support the idea that the occurrences of most of the DL-S effects seem to strongly depend on the presence of a second nominal constituent in the structure of wh-phrases. This second nominal can be either a Functional Noun inside the wh-item used as wh-pronoun or an overt second noun as in wh-partitive phrases.
The contribution of this thesis to linguistic theorizing is not a full-fledged technical analysis of every single DL-S effect, but rather the systemisation proposed. Although a lot of terminology is introduced, the outcome of this proliferation of terms is a sharper picture of the intricate relations between the constituents of the wh-items used as wh-determiners and the Nominal Restrictor. Another main conclusion is that the concept of D-linking is not a basic notion. It is comprised of four components (of which DL-Syntax and Morphological-DL have been scrutinized in this thesis). This assumption explains why DWH do not constitute a homogeneous class. The gradual character of D-linking (i.e. the fact that certain wh-determiner constructions show only a subset of DL-S effects even if they are headed by what could faithfully be classified as a/the Token-wh determiner of the respective language) is argued to be related to the fact that the Token-reading itself can have several triggers.
Die Sulfonyl-Gruppe (-SO2-) ist ein weit verbreitetes Strukturmotiv in der organischen Chemie und Bestandteil vieler biologisch aktiver Moleküle, insbesondere Arzneistoffen. Zwei der am häufigsten auftretenden Gruppen sind Sulfone und Sulfonamide, die in über 100 zugelassenen Medikamenten und 10% der meistverkauften Medikamente sind. Insofern kommt der Entwicklung neuer Synthesemethoden eine große Bedeutung zu. Dabei stehen besonders einfache, wirtschaftliche und zeitsparende Vorgehensweisen im Vordergrund, die eine große Bandbreite an neuen Substanzen generieren können. Ein Ansatz hierfür sind Multikomponenten- oder Eintopfreaktionen.
Aufgrund der Wichtigkeit dieser zwei Strukturklassen, sollen im Rahmen der hier vorliegenden Doktorarbeit neue Syntheserouten für Sulfone und Sulfonamide entwickelt werden. Besonderes Augenmerk wird auf die die Einführung der SO2-Einheit während der Reaktionsführung gelegt. Im Vergleich zu bereits existierenden Verfahren ist dies ein enormer Fortschritt, da die Mehrheit der bekannten Routen auf Schwefel- oder Schwefeldioxid-haltige Startmaterialien zurückgreift.
In der vorliegenden Arbeit gelang es, einen synthetischen Zugang zu Arylsulfonen basierend auf von Natrium-, Lithium-, Magnesium- und Zinksulfinaten zu finden. Diese Reaktion besitzt eine sehr große Anwendungsbandbreite und setzt sowohl Aryl- als auch Alkylsulfinate effizient um. Außerdem weisen Reaktionen mit unsymmetrischen Diaryliodoniumsalzen hohe Chemoselektivitäten auf.
Auf der Grundlage auf der Reaktion zwischen Natriumsulfinaten und Iodoniumsalzen wurde eine simple Route zur Synthese von Diarylsulfonen abgeleitet, jedoch war hierbei die Sulfonylgruppe noch Bestandteil eines der Edukte. Um die SO2-Einheit während der Reaktion einführen zu können, wurde ein praktisches Eintopf-Protokoll entwickelt, welches die direkte Umsetzung von (hetero)aromatischen und alkylischen Halogeniden zu Arylsulfonen gestattet. Diese innovative Methode besteht aus folgenden vier Schritten: (1) Generierung des Organometallreagenzes via Halogen-Metall-Austausch, direkte Metallinsertion oder Deprotonierung; (2) Reaktion des Organometallreagenzes mit SO2 zum Sulfinat; (3) Entfernen des SO2-Überschusses und flüchtiger Komponenten und (4) Umsetzung des nicht aufgereinigten Sulfinates mit einem Iodoniumsalz.
Desweiteren wird in dieser Arbeit ein neuartiger Übergangsmetall-katalysierter Ansatz zur Darstellung von Diarylsulfonen ausgehend von Arylhalogeniden und Sulfinaten diskutiert. Erste Experimente deuten auf Nickel-Katalysatoren als gute Wahl für die Reaktion. Optimierungsreaktionen zeigten eine starke Abhängigkeit der Ausbeute in Hinsicht auf die Bisswinkel der an das zentrale Nickelatom koordinierten Liganden. Da die bis dato besten Ergebnisse mit dem Komplex [o-tol-Ni(PPh2Me)2Cl] erzielt wurden, wird der [o-tol-Ni(PMe3)2Cl]-Komplex momentan in unserem Labor weiteren Studien unterzogen. Bislang ist davon auszugehen, dass dieser Katalysator hervorragende Ergebnisse liefert und zu einer allgemein gültigen Methode führt.
In weiteren Kapiteln wird die Anwendbarkeit von SO2-Surrogaten, Metabisulfiten „S2O52-„ oder DABSO; untersucht; mit dem Ziel eine Eintopf- oder Multikomponentenreaktion zu entwickeln.
Zum einen wird die Entwicklung einer Ein-Topf-Reaktion von Alkylhalogeniden mit Metabisulfiten und Organozinkreagenzien zur Darstellung von Alkylarylsulfonen vorgestellt. Darüber hinaus wird eine Übergangsmetall-katalysierte Multikomponenten Reaktion zur Synthese von Sulfonsäureamiden vorgestellt. Eine Reaktion zwischen Aminen, Arylhalogeniden und DABSO als SO2-Quelle wurde in Form einer Palladium-katalysierten Aminosulfonylierung entwickelt.
Die vorliegende Dissertation mit dem Titel: Ecophysiological monitoring of Oaks in Central Europe, introduced in the framework of proactive climate change mitigation beschäftigt sich mit der Anwendung zerstörungsfreier, radiometrischer Methoden zur Bestimmung von Pigment- und Stickstoffkonzentrationen und der photosynthetischen Funktionalität in Blättern von heimischen und gebietsfremden Eichen und ihre Beeinflussung durch Trocken-, Hitze- und Kältestress.
Die Eichenarten Quercus robur L. (Stieleiche), Q. pubescens Willd. (Flaumeiche), Q. frainetto Ten. (Ungarische Eiche), Q. ilex L. (immergrüne Steineiche) und Q. rubra L. (amerikanische Roteiche) wurden im Frühjahr 2011 auf einer Versuchsfläche im Frankfurter Stadtwald gepflanzt, um ihre Nutzung als potentielle Waldbäume in einem sich ändernden Klima zu untersuchen. Über eine Dauer von zwei Jahren wurden diese Arten mit einem hohen Maß an blattspezifischer Merkmalsvariabilität beobachtet und beprobt. Ziel war es, die interspezifischen Unterschiede und die jahreszeitliche Dynamik von morphologischen und chemischen Blattmerkmalen sowie die Beeinflussung der radiometrischen Bestimmung des Chlorophyllgehaltes (und damit assoziierten Komponenten wie z.B. Blattstickstoffgehalt und Karotinoiden) und der photosynthetischen Funktionalität durch klimatische Umweltbelastungen in Eichen zu untersuchen. Die Analyse der Blattproben zielte neben der Bestimmung der Beziehung zwischen absoluten und optisch ermittelten Pigmentgehalten auf die Ermittlung des Einflusses der Blattstruktur auf die Lichttransmission im roten und infrarotem Bereich des Elektromagnetischen Spektrums ab, sowie auf die artspezifische Korrelation von Blattstickstoff zu Blattchlorophyll zu dessen indirekte Quantifizierung. Des Weiteren wurden Versuche zur Trocken- und Hitzestressanpassung durchgeführt, um eine potentiell artspezifische Stressantwort, sowie eine mögliche Beeinflussung der aufgenommenen radiometrischen Messwerte zu ermitteln. Ein zusätzliches Monitoringprogramm im Winter 2012/2013 mit einer Dauer von sechs Monaten ermöglichte die Überprüfung der Anpassungsfähigkeit der immergrünen Steineiche (Q. ilex) an mitteleuropäische Winterbedingungen und die Veränderung der photosynthetischen Funktionalität unter Kältestress. Messungen im Zusammenhang mit der praktischen Anwendbarkeit der zerstörungsfreien, optischen Methode und zur Bereitstellung von Referenzdaten für zukünftige Evaluierungen komplementieren die Untersuchungen.
Signifikante, artspezifische Unterschiede wurden in den blattmorphologischen Schlüsselmerkmalen in den Quercus-Arten ermittelt. Die artspezifischen Unterschiede in den morphologischen Blattmerkmalen beeinflussten auf signifikante Weise die Beziehung zwischen absoluten, massebasierten Pigment- und Stickstoffgehalten und deren radiometrischen Bestimmung. Wurden die Pigmentgehalte hingegen auf die Blattfläche bezogen und die Stickstoffgehalte mittels des Verhältnisses von Blattfläche zu Trockenmasse korrigiert, zeichnete sich eine Beziehung zwischen absoluten und optisch ermittelten Werten ab, der jegliche jahreszeitliche oder artspezifisch morphologische Variabilität fehlte und die somit für alle Quercus-taxa anwendbar ist. Koeffizienten für die Berechnung von flächenbezogenen Gehalten von Gesamtchlorophyll, Chl a, Chl b und Carotinoiden für die jeweiligen Quercus-taxa, wie auch für ein artübergreifendes Modell wurden ermittelt, um die Bestimmung dieser Gehalte während aller Entwicklungsstufen zu ermöglich. Aus der jahreszeitlichen Entwicklung der Pigmentgehalte konnten drei deutliche Phasen abgeleitet werden: Die Phase der Blattentwicklung im Frühling, einer Plateauphase mit geringen Veränderungen (“core vegetation time”) und die Phase des Pigmentabbaus während der Herbstlaubfärbung. Die Übergänge zwischen diesen Phasen variierten zum Teil erheblich zwischen einzelnen Individuen einer Art sowie zwischen den Arten, was Unterschiede in der potentiellen, jährlichen Kohlenstoffaufnahme nach sich zieht. Stressbedingungen, wie Hitze- Kälte- oder Trockenstress, können zu Veränderung von Fluoreszenzparametern ohne gleichzeitige Änderung des Pigmentgehaltes führen, wie auch die indirekte Bestimmung von mit Chl assoziierten Komponenten (Carotinoide, Chl a, Chl b) mittels optischer Bestimmung (durch die Veränderungen von Pigmentverhältnissen) beeinflussen.
Im Rahmen des Forschungsprojektes konnten, Modelle zur Berechnung von Blattpigmenten und Blattstickstoff aus optischem Messdaten, Veränderungen der photosynthetischen Funktionalität, sowie Referenzdaten für die zukünftig nutzbaren Eichenarten hinsichtlich artspezifischer und jahreszeitlicher Variabilität unter mitteleuropäischen Umweltbedingungen ermittelt werden, die eine Nutzung und Einordnung von zerstörungsfreien, optischen Messwerten zur Ermittlung von Vitalitätsunterschieden in Eichen ermöglichen.
ISOE Policy Briefs – Neue Reihe zu Ergebnissen der Nachhaltigkeitsforschung +++ Autonome Fahrzeuge: eine Chance für den ÖPNV +++ Trotz Hitzewelle: Noch verzichtet die Mehrheit der Deutschen auf Klimaanlagen +++ ISOE-Mobilitätsforschung: Sharing-Konzepte in der Rhein-Main-Region +++ Neues Forschungsprojekt zur sozial-ökologischen Transformation im Bereich Wohnen und Mobilität +++ Aus dem ISOE: Nachhaltigkeitspreis für ISOE-Forscherin +++ Termine +++ Publikationen
Blaue Zukunft – Die kostbare Ressource Wasser und wie wir damit umgehen (müssen) +++ Leseempfehlung: Nachhaltige Wissenschaft im Anthropozän +++ Wegweiser Hauskauf: Neueigentümer für die energetische Sanierung motivieren +++ Klima- und Umweltschutz im Alltag: Leitfaden für die Zielgruppen MigrantInnen und Geringverdienende +++ Nachhaltiges Wasserressourcen-Management für das Einzugsgebiet der Nidda +++ ISOE-Forschungsschwerpunkt Biodiversität und Bevölkerung +++ Gesellschaftliche Trends und Mobilität im urbanen Raum +++ GreenTec Award 2015 für Forschungsprojekt Semizentral +++ Thomas Jahn im Wissenschaftlichen Beirat der Zeitschrift Sustainability +++ Aus dem ISOE +++ Termine +++ Publikationen
Die Debatte, wie die Organisation des universitären Lehrbetriebs an deutschen Hochschulen verbessert werden kann, wurde in den vergangenen Monaten intensiv medial begleitet. Eine ehrliche Diskussion über realistisch umsetzbare Reformen ist notwendig. Ich plädiere vor allem für eine Diversifizierung der Prüfungsleistungen, wodurch sich gleichzeitig die Vorbereitung auf Seminare verbessern könnte. Darüber hinaus wäre ein konsensorientierteres Verhältnis zwischen Dozenten_innen, Administration und Studentenschaft wünschenswert.
Kaisers neue Kleider: Anmerkungen zur Kritik der Hochschullehre im "akademischen Kapitalismus"
(2015)
An dieser Stelle beschrieb Stefan Müller kürzlich Drei Vorschläge für eine Verbesserung der Lehre an deutschen Universitäten. Er reagierte damit auf Vorwürfe des finnischen Studenten Juuso Nisula, der unter dem Titel Acht Gründe, nie wieder in Deutschland zu studieren seinem Unmut über das intransparente und austauschhinderliche Studienklima an der Universität Köln massenmedientauglich Luft verschafft hatte – einer Universität übrigens, die ihrerseits auf Nisula reagierte, wenngleich so allgemein, wie man es auch von den standardisierten PR-Abteilungen größerer Unternehmen gewohnt ist: Mit herablassender Freundlichkeit pusten sie berechtige Verbraucherbeschwerden in den Wind und flaggen lieber ihre austauschbaren Imagesätzchen aus.
Photosynthesis is one of the most vital processes that takes place on Earth. Due to its global significance related to food, energy and material production, photosynthesis research is one of the leading scientific fields in the contemporary world. Particular interest in photosynthesis research is focused on diatoms and as one of the major players of marine phytoplankton, diatoms have a huge impact on global photosynthesis.
Diatoms originated from a secondary endosymbiosis that took place between a putative photosynthetic red algal ancestor and a heterotrophic eukaryote. Secondary endosymbiosis resulted in the formation of chloroplasts with four membranes. Centric diatoms (e.g. Thalassiosira pseudonana or Cyclotella meneghiniana) usually possess many small chloroplasts, while pennates (e.g. Phaeodactylum tricornutum) have several larger ones, or even only one which can occupy half of the cell volume...