Refine
Year of publication
- 2009 (25) (remove)
Document Type
- Doctoral Thesis (20)
- Article (3)
- Conference Proceeding (2)
Language
- English (25) (remove)
Has Fulltext
- yes (25)
Is part of the Bibliography
- no (25)
Keywords
Institute
- Institut für Physik (10)
- Institut für Geographie und Geologie (2)
- Abteilung für Mikrobiologie und Molekularbiologie (1)
- Institut für Anglistik/Amerikanistik (1)
- Institut für Biochemie (1)
- Institut für Epidemiologie u. Sozialmedizin (1)
- Institut für Immunologie u. Transfusionsmedizin - Abteilung Immunologie (1)
- Institut für Mathematik und Informatik (1)
- Institut für Slawistik (1)
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung (UMG) (1)
- Klinik für Psychiatrie und Psychotherapie (1)
- Klinik und Poliklinik für Neurologie (1)
- Poliklinik für Kieferorthopädie, Präventive Zahnmedizin und Kinderzahnheilkunde (1)
- Zoologisches Institut und Museum (1)
Publisher
- IOP Publishing (4)
- De Gruyter (1)
ZfSl 54 (2009) 2, 224-240 Ulrike Jekutsch Zur Schau gestellte Fiktion: Die Erfindung polnischer Frühgeschichte in Słowackis Tragödien „Balladyna“ und „Lilla Weneda“SummaryJuliusz Słowacki’s tragedies “Balladyna” (1834, publ. 1839) and “Lilla Weneda” (1840) are set in legendary pre-historical times. Reflecting the Polish nation-building process, they outline invented episodes und char-acters in the beginnings of the first Polish state. With these plays, Słowacki wanted to give his people poeti-cally created legends, which would enrich their scanty stock of stories from pre-historical times and fill out the gaps in their national historical knowledge. Słowacki’s foreword to “Balladyna” serves as an introduc-tion to a projected cycle of plays about Polish pre-history. Here, the playwright openly exposes the fictional-ity of both characters and plot, and he draws attention to the many historical inconsistencies and anachro-nisms in the text. At the same time, he claims that the intrinsic truth of poetry ranks higher than mere factual accuracy, and that his plays, despite their historical inaccuracy, may become Polish-pre-history. His inven-tion of new episodes of Polish pre-history is aimed polemically against contemporary historiography – espe-cially against two issues, i. e. first, romantic historiography’s pretension to play the role of universal art (Universalwissenschaft), and secondly, the traditional Polish idealization of known figures of pre-history. The article discusses these two aspects of Słowacki’s plays, focussing on his polemics against contemporary Polish historiography and especially against Joachim Lelewel.
Application of quantum cascade laser absorption spectroscopy to studies of fluorocarbon molecules
(2009)
The recent advent of quantum cascade lasers (QCLs) enables room-temperature mid-infrared spectrometer operation which is particularly favourable for industrial process monitoring and control, i.e. the detection of transient and stable molecular species. Conversely, fluorocarbon containing radio-frequency discharges are of special interest for plasma etching and deposition as well as for fundamental studies on gas phase and plasma surface reactions. The application of QCL absorption spectroscopy to such low pressure plasmas is typically hampered by non-linear effects connected with the pulsed mode of the lasers. Nevertheless, adequate calibration can eliminate such effects, especially in the case of complex spectra where single line parameters are not available. In order to facilitate measurements in fluorocarbon plasmas, studies on complex spectra of CF4 and C3F8 at 7.86 μm (1269 – 1275 cm-1) under low pressure conditions have been performed. The intra-pulse mode, i.e. pulses of up to 300 ns, was applied yielding highly resolved spectral scans of ∼ 1 cm-1 coverage. Effective absorption cross sections were determined and their temperature dependence was studied in the relevant range up to 400 K and found to be non-negligible.
Fluorocarbon containing capacitively coupled radio frequency (cc-rf) plasmas are widely used in technical applications and as model systems for fundamental investigations of complex plasmas. Absorption spectroscopy based on pulsed quantum cascade lasers (QCL) was applied in the mid-IR spectral range of 1269-1275 cm-1. Absolute densities of the precursor molecule CF4 and of the stable product C3F8 were measured with a time resolution of up to 1 ms in pulsed CF4/H2 asymmetrical cc-rf (13.56 MHz) discharges. For this purpose both the non-negligible temperature dependence of the absorption coefficients and the interference of the absorption features of CF4 and C3F8 had to be taken into account in the target spectral range. Therefore, at two different spectral positions composite absorption spectra were acquired under the same plasma conditions in order to discriminate between CF4 and C3F8 contributions. A total consumption of∼ 12 % was observed for CF4 during a 1 s plasma pulse, whereas C3F8 appeared to be produced mainly from amorphous fluorocarbon layers deposited at the reactor walls. A gas temperature increase by ∼ 100 K in the plasma pulse was estimated from the measurements. Additionally, not yet identified unresolved absorption (potentially from the excited CF4 molecule) was found during the àon-phase'.
Tunable diode laser absorption spectroscopy of argon metastable atoms in Ar/C2H2 dusty plasmas
(2009)
The tunable diode laser absorption spectroscopy method was used to measure Ar metastable density in order to study the dust growth process in hydrocarbon-containing plasmas. A simple model was proposed that successfully interprets the experimental results of pristine plasmas. The model is also suitable for explaining the influence of dust particle size on metastable density and for examining the dust growth process. The metastable density responded strictly to the formation of dust particles and their growth in processing plasmas. Using metastable density as an indicator is, therefore, a non-intrusive and effective method for the study of the dust growth process in hydrocarbon-containing plasmas.
An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles with the surrounding plasma for diagnostic purposes. Local electric fields can be determined from the behaviour of particles in the plasma, e.g. particles may serve as electrostatic probes. Since in many cases of applications in plasma technology it is of great interest to describe the electric field conditions in front of floating or biased surfaces, the confinement and behaviour of test particles is studied in front of floating walls inserted into a plasma as well as in front of additionally biased surfaces. For the latter case, the behaviour of particles in front of an adaptive electrode, which allows for an efficient confinement and manipulation of the grains, has been experimentally studied in terms of the dependence on the discharge parameters and on different bias conditions of the electrode. The effect of the partially biased surface (dc and rf) on the charged micro-particles has been investigated by particle falling experiments. In addition to the experiments, we also investigate the particle behaviour numerically by molecular dynamics, in combination with a fluid and particle-in-cell description of the plasma.
The Syilx Okanagan environmental ethic is a philosophy expressed in the practice of Indigeneity as a social (cultural) paradigm and is identified by an inter-reliant experience in the land, as demonstrated in land-use practice which is shaped by the land’s realities as observed, learned and communicated to succeeding generations. Syilx Okanagan Indigeneity reflects an epistemology that optimum human wellbeing cannot be achieved through a human centered ethic but must focus on the optimum ability for the environment to regenerate itself. Syilx Okanagan stories convey the social experience and act as a records system to preserve, maintain and transfer the knowledge of the land. On one level, captikwl contain essential specific environmental knowledge as an oral documentation method, while on another level, as literature, captikwl reconstructs the ethos of interdependency specific to the ecology of the Syilx Okanagan territory through reenactment of nature’s interactions. captikwl in the Nsyilxcen language mimics the dynamic aspects of nature’s required regenerative principles to each succeeding generation, and acts as a feed-back loop reconstructing the social paradigm as an environmental ethic. captikwl might be seen as a distinctly Indigenous human adaptive response scheme within a natural system as it constructs the Syilx Okanagan world and results in behavior with sustainable outcome in the environment. captikwl is a distinct oral artistry that must be read through a literary framework cognizant of oral memory device, structure and Syilx Okanagan context. Okanagan author Morning Dove’s collection of Okanagan stories, as well as, the Mattina and DeSautel bilingual collections and other original version captikwl were consulted. Captikwl demonstrates the concept of tmixw which better translates as a life-force. The word for land is tmxwulaxw, which translates better as a life-force-place, rather than land as location or ecology type. Syilx society demonstrates an “ecological conscience” as the common text through captikwl which is enacted in their social institutions in the manner theorized by respected American conservationist Aldo Leopold, as desirable to achieve within society. The Syilx environmental ethic, rather than a sustainable human ethic of utility, is a willingness to live within a strict imperative to continuously sustain a unity of existence through societal knowledge and reverent practice of respect toward all life-forms. The Syilx environmental ethic diverges from ecocentrism, as articulated by Callicott, in recognizing a fundamental distinction between non-life forms and life forms, in their ability for self-regeneration through inter-reliance, as the focus for delineating moral considerability. The Syilx environmental ethic differs from biocentrism, as articulated by Taylor, in recognizing moral considerability as resting with the on-going life form which is capable of regeneration within its ecology, rather than the singular biological unit. The Syilx environmental ethic also differs from the concept of the ethics of place, as articulated by Berthold-Bond and characterized as an ethical bioregional human utility of a location. Tmixw is the life-force which makes up the tmxwulaxw or life-force-place and the humans are only “placed” as a life-force themselves through Indigeneity as a social paradigm within a criteria of full reciprocity in the regeneration of all life forms of a place. The Syilx environmental ethic also differs from the ethic of sustainability proposed by Daly as a steady state economic model of human utilitarianism, in the positioning of nature treated as capital, to be prudently developed in a way that off-sets depletions of renewable and non-renewable resources in meeting human requirements. The Syilx Okanagan view of economy, while structurally a sustainability model, does not construct value based on human utility as a defining line in decision-making as to which life forms are to be devalued and displaced. Syilx Indigeneity is guided through a societal dialogue practice of Enowkinwixw, a process of decision-making structured to include living within the requirements of the land to fully regenerate. Syilx Okanagan Indigeneity frames an environmental ethic from a tmixwcentric position and offers a model proposing an ethic of re-indigenization as a path to sustainability. The thesis proposes a common text for human society in the form of such literatures, since literature is widely accessible, which demonstrate, imbed and advocate a regenerative land ethic towards the re-indigenization of place.
Tourette syndrome has been associated with impairments of performance monitoring and alterations of attentional and executive functions. This impairment has been linked to fronto-striatal dysfunctions, which comprise the same braincircuits that are actively engaged in the suppression of tics. We compared behavioral performance and performance monitoring in nineteen boys with Tourette syndrome (TS) (mean age 12.64 years, ± 2.05) and nineteen age-matched controls (mean age 13.16 years, ± 2.29) in a Go/NoGo paradigm. This paradigm was designed to test for problems with inhibition and attention when withholding the response to NoGo targets following repetitive Go targets. The results indicated similar performance accuracy in the TS group and the control group. TS participants showed the expected pattern of Post-Error Slowing, but responded significantly also slower to correct Go trials than the controls. The reaction times (RT) to NoGo targets in commission errors, however, did not differ between the groups. The results suggest that boys with TS develop inhibitory adaptive strategies (overall slower reaction times) to maintain high performance accuracy. These effects may be suspended prior to and during NoGo commission errors.
We present classical and hybrid modeling approaches for genetic regulatory networks focusing on promoter analysis for negatively and positively autoregulated networks. The main aim of this thesis is to introduce an alternative mathematical approach to model gene regulatory networks based on piecewise deterministic Markov processes (PDMP). During somitogenesis, a process describing the early segmentation in vertebrates, molecular oscillators play a crucial role as part of a segmentation clock. In mice, these oscillators are called Hes1 and Hes7 and are commonly modeled by a system of two delay differential equations including a Hill function, which describes gene repression by their own gene products. The Hill coefficient, which is a measure of nonlinearity of the binding processes in the promoter, is assumed to be equal to two, based on the fact that Hes1 and Hes7 form dimers.However, by standard arguments applied to binding analysis, we show that a higher Hill coefficient is reasonable. This leads to results different from those in literature which requires a more sophisticated model. For the Hes7 oscillator we present a system of ordinary differential equations including a Michaelis-Menten term describing a nonlinear degradation of the proteins by the ubiquitinpathway. As demonstrated by the Hes1 and Hes7 oscillator, promoter behavior can have strong influence on the dynamical behavior of genetic networks. Since purely deterministic systems cannot reveal phenomenons caused by the inherent random fluctuations, we propose a novel approach based on PDMPs. Such models allow to model binding processes of transcription factors to binding sites in a promoter as random processes, where all other processes like synthesis, degradation or dimerization of the gene products are modeled in deterministic manner. We present and discuss a simulation algorithm for PDMPs and apply it to three types of genetic networks: an unregulated gene, a toggle switch, and a positively autoregulated network. The different regulation characteristics are analyzed and compared by numerical means. Furthermore, we determine analytical solutions of the stationary distributions of one negatively, and three positively autoregulated networks. Based on these results, we analyze attenuation of noise in a negative feedback loop, and the question of graded or binary response in autocatalytic networks.
In 1992, the international regime 'Agenda 21' was agreed upon. Accordingly, countries worldwide have been undergoing reforms in their water management into Integrated Water Resources Management (IWRM). The implementation is promoted by international actors. The main institutional aspects of IWRM are the river basin approach, clear property rights allocation, and application of economical instruments. In former centrally planned economies, the process of IWRM implementation has been coincided with transformation for the market economy. The implementation of institutional aspects of IWRM in countries under transition is connected with high transaction costs. Against this background, the comparative empirical study was initialised in order to analyse institutional change of water management towards IWRM in Vietnam and in Poland. Two models of river basin organisations were examined. Consequently, pros and cons of decentralised polycentric and hierarchical unicentric river basin organisations have been evaluated. Formal institutions were studied with the use of an in-depth review of legislation in Vietnam and in Poland. The EU Water Frame Directive (EU WFD) and other international policies were also examined. For the empirical study in Vietnam and in Poland, actors were interviewed as experts. The results of the study on both countries were discussed separately, and conclusions were drawn in a comparative manner. Water management reforms towards IWRM in Vietnam and in Poland have been generating multi-level governance processes including international, national and sub-national levels. The implementation of IWRM in Vietnam is supported by international donor agencies. In Poland, the implementation of the EU WFD is coordinated by the European Commission in a hierarchical manner. In comparison to international joint-development projects in Vietnam, the European Commission enforces international IWRM policy more effectively. Since the resumption of ODA in early 1990s, water resources management has been institutionalised in Vietnam by international support. In 1998, a Water Law was established in Vietnam. The intended separation of water resources management from water service provisions caused fragmentation between the Ministry of Natural Resources and Environment, and the Ministry of Agriculture and Rural Development, respectively. This ‘silo-effect’ has been intensified by the competition for international ODA. The power struggles affect even agencies within ministries. Polycentric river basin committees have been established as entities subordinated to the Ministry of Agriculture and Rural Development, as well as the Ministry of Natural Resources and Environment. However, because of weak property rights allocation and the absence of administrative powers, the river basin organisations work ineffectively. The river basin has not yet been established as a sub-national area of political action. Decisions sustained to be made at central level and are affected by the information problem due to largely centralised organisations of Vietnamese water management. The sub-national level is characterised by very low planning and management capacities. In Poland, unicentric river basin organisations were established in 1991. They are aligned with hydrological borders. Water resources planning and management are carried out according to river basins and water regions in order to implement the EU WFD. The river basin has been established as a new area of decision-making. Conflicts between local-governments have been resolved after the reforms. Nevertheless, spatial management planning, environmental protection planning, water service delivery, etc., are further carried out by local self-governments. To integrate water resources planning and management with these services, horizontal coordination is of critical importance. However, this is hampered by problems of ‘spatial fit’. Moreover, a high degree of horizontal cross-border communication increases information problems in hierarchical organisations. Thus, features of polycentric governance models become increasingly important in order to fully implement the EU WFD in Poland.
Discovery of novel Baeyer-Villiger monooxygenases and their application in organic synthesis.
(2009)
The application of BVMOs in kinetic resolution is a versatile alternative for the synthesis of optically pure esters. Within this thesis BVMOs proved to be highly active against a broad range of linear and aryl aliphatic ketones yielding a variety of enantiopure products. Among the beta-hydroxy ketones several CHMOs and BVMOPsfl showed the best results (E > 100), whereas the application of the latter enzyme also allowed access to the abnormal esters (regioisomeric excess > 40%). Interestingly, some enzymes showed a reduced activity and selectivity with a growing chain length of the ketone, suggesting that middle-chain ketones (C8-C10) might be preferred. Moreover, the production of optically pure 1,2-diols was observed (yields 8-50%), resulting from an in vivo hydrolysis of the 2-hydroxy alkyl acetates. Regarding the N-protected beta-amino ketones, results were different. While the majority of CHMOs catalyzed linear substrates showing high enantioselectivities (for CHMOBrevi1 and CHMOBrachy E > 100, c = 40-50%), BVMOPsfl did not convert nitrogen bearing linear ketones, although this might also be justified with the methylcarbamate protecting group. Interestingly, the number of BVMOs catalyzing oxidation of spatially more demanding linear branched beta-amino ketones was greatly reduced, indicating steric hindrance that was also combined with a decrease in selectivity. Similar to the observation for beta-hydroxy ketones, also the 2 amino alkyl acetates hydrolyzed furnishing 2-amino alcohols (yields 9-52%). Moreover, hydrolysis of the “abnormal“ esters allowed an alternative access to valuable native and non-native β-amino acids. In a two step process, using CDMO from R. ruber and CAL-B, it was possible to generate N-protected (+)-beta-leucine. During kinetic resolutions of aryl aliphatic ketones it was observed that the highest enantio¬selectivities could be achieved utilizing HAPMOJD1, HAPMOACB and PAMO, enzymes typically preferring aromatic substrates. Biotransformation with 3-phenyl-2-butanone revealed an E-value > 100 for HAPMOJD1 (S-selective). Nevertheless, also BVMOPsfl converted this sub¬strate (E = 43), and also CHMOAcineto and CPMO oxidized it, although selectivity was rather low (E < 5). Interestingly, BVMOKT2440 was the only examined enzyme showing R selectivity (E = 13). Additionally, increasing the scale and performing biotransformation in a baffled flask could increase enantioselectivity of BVMOPsfl from E = 43 to 82. The discovery of novel enzymes with diverse properties is still a main goal of the biotechnological industry. Within these studies, two BVMOs (BVMOKT2440 and HAPMOJD1) could be successfully amplified from genomic DNA using different PCR-methods. Then, expression in E. coli was optimized, revealing that the reduction of expression temperature, implementation of E. coli JM109 or RosettaTM (DE3), possessing the pRARE plasmid to facilitate translation of rare codons in the latter case, and/or co-expression of chaperones (pGro7: GroEL/ES-familiy) could increase the amount of soluble and active protein. Both enzymes were subjected to biocatalysis and it was found that BVMOKT2440 preferentially oxidized linear ketones, while HAPMOJD1 dominantly converted aryl aliphatic ketones. The latter enzyme could be purified by anion exchange and affinity chromatography allowing examination of kinetic parameters. Thereby, HAPMOJD1 displayed lowest KM-values for acetophenone derivatives bearing their substituent in para-position (KM < 320 µM). Moreover, also aldehydes and heteroaromatic compounds were oxidized and also sulfoxidation was observed. Interestingly it was found, that both BVMO genes are located in the direct neighborhood of a dehydrogenase and a hydrolase. This led to the suggestion that these enzymes may be metabolically connected in the degradation of their natural substrate.
This thesis constitutes a computational study of charge and ion drag force on micron-sized dust particles immersed in rf discharges. Knowledge of dust parameters like dust charge, floating potential, shielding and ion drag force is very crucial for explaining complex laboratory dusty plasma phenomena, such as void formation in microgravity experiments and wakefield formation in the sheaths. Existing theoretical models assume standard distribution functions for plasma species and are applicable over a limited range of flow velocities and collisionality. Kinetic simulations are suitable tools for studying dust charging and drag force computation. The main aim of this thesis is to perform three dimensional simulations using a Particle-Particle-Particle-Mesh ($P^3M$) model to understand how the dust parameters vary for different positions of dust in rf discharges and how these parameters on a dust evolve in the presence of neighboring dust particles. At first, rf discharges in argon have been modelled using a three-dimensional PIC-MCC code for the discharge conditions relevant to the dusty plasma experiments. All necessary elastic and inelastic collisions have been considered. The plasma background is found collisional, charge-exchange collisions between ions and neutrals being dominant. Electron and ion distributions are non-Maxwellian. The dominant heating mechanism is Ohmic. Then, simulations have been done to compute the dust parameters for various sizes of dust located at different positions in the rf discharges. Dust charge and floating potential in the presheath are slightly larger than the values in the bulk due to the higher electron flux to the dust particle in the presheath. From presheath to the sheath the charge and floating potential values decrease due to the decrease of the electron current to the dust. A linear dependence of dust potential on dust size has been found, which results in a nonlinear dependence of the dust charge with the dust size when the particle is assumed to be a spherical capacitor. This has been verified by independently counting the charges collected by the dust. %where indeed it has been noted that the dust charge %scales nonlinearly with the dust size. The computed dust parameters are also compared with theoretical models. Simulated dust floating potentials are comparable to values obtained from Allen-Boyd-Reynolds (ABR) and Khrapak models, but much smaller than the values obtained from Orbit Motion Limited (OML) model. The dust potential distribution behaves Debye-H\"{u}ckel-like. The shielding lengths are in between ion and electron Debye lengths. % indicating shielding by both ions and electrons. Further, the orbital drag force is typically larger than the collection drag force. The total drag force for the collisional case is larger than for the collisionless case and it scales nonlinearly with the dust size. The collection drag values and size-scaling agrees with Zobnin's model. The charging and drag force computation is then extended to two and multiple static dust particles in the rf discharge to study the influence of neighboring dust particles on the dust parameters. Initially, the dust parameters on two dust particles are computed for various interparticle separation distances and for dust particles placed at different locations in the rf discharge. It is observed that for dust separations larger than the shielding length the dust parameters for the two dust particles match with the single dust particle values. As the dust separation is equal to or less than the shielding length the ion drag force increases due to the buildup of a parallel drag force component. However, the main dust properties like charge, potential, vertical component of ion drag are not affected considerably. This is attributed to the smaller collection impact parameter values compared to the dust separation. %This is because the %collection impact parameter values in the sheath and the presheath are smaller %than the smallest dust separation and in case of the dust in the bulk, the %collection impact parameter is comparable with the dust separation. Then the dust charges on multiple dust particles located at different positions in the discharge and arranged along the discharge axis are also computed. It is found that the charges of the multiple dust particles in the bulk or presheath do not differ much from the single particle values at that location. But the dust charges of multiple dust particles located in the sheath drastically differ from the single dust parameter values. Due to ion focusing from dust particles in the upper layers, the ion current increases to dust particles in the lower layers resulting in smaller charge values. This is as well the case where dust particles are vertically aligned as in the standard experiments of dusty plasmas. In conclusion, this work used a fully kinetic (PIC and MD or $P^3M$) model to study the physics of dust charging in rf plasmas. Our simulations revealed that the dust parameters vary considerably from the bulk to the sheath. The CX collisions increase flux to the dust thereby affecting the dust parameters and their scaling with dust size. Also, a dust particle affects the charging dynamics of its neighbor only when their separation is within the shielding length. In the plasma sheath, ion focussing can cause great reduction in dust charges.
Infrared laser absorption spectroscopy (IRLAS) employing both tuneable diode and quantum cascade lasers (TDLs, QCLs) has been applied with both high sensitivity and high time resolution to plasma diagnostics and trace gas measurements.
TDLAS combined with a conventional White type multiple pass cell was used to detect up to 13 constituent molecular species in low pressure Ar/H2/N2/O2 and Ar/CH4/N2/O2 microwave discharges, among them the main products such as H2O, NH3, NO and CO, HCN respectively. The hydroxyl radical has been measured in the mid infrared (MIR) spectral range in-situ in both plasmas yielding number densities of between 1011 ... 1012 cm-3. Strong indications of surface dominated formation of either NH3 or N2O and NO were found in the H2-N2-O2 system. In methane containing plasmas a transition between deposition and etching conditions and generally an incomplete oxidation of the precursor were observed.
The application of QCLs for IRLAS under low pressure conditions employing the most common tuning approaches has been investigated in detail. A new method of analysing absorption features quantitatively when the rapid passage effect is present is proposed. If power saturation is negligible, integrating the undisturbed half of the line profile yields accurate number densities without calibrating the system. By means of a time resolved analysis of individual chirped QCL pulses the main reasons for increased effective laser line widths could be identified. Apart from the well-known frequency down chirp non-linear absorption phenomena and bandwidth limitations of the detection system may significantly degrade the performance and accuracy of inter pulse spectrometers. The minimum analogue bandwidth of the entire system should normally not fall below 250 MHz.
QCLAS using pulsed lasers has been used for highly time resolved measurements in reactive plasmas for the first time enabling a time resolution down to about 100 ns to be achieved. A temperature increase of typically less than 50 K has been established for pulsed DC discharges containing Ar/N2 and traces of NO. The main NO production and depletion reactions have been identified from a comparison of model calculations and time resolved measurements in plasma pulses of up to 100 ms. Considerable NO struction is observed after 5 ... 10 ms due to the impact of N atoms.
Finally, thermoelectrically cooled pulsed and continuous wave (cw) QCLs have been employed for high finesse cavity absorption spectroscopy in the MIR. Cavity ring down spectroscopy (CRDS) has been performed with pulsed QCLs and was found to be limited by the intrinsic frequency chirp of the laser suppressing an efficient intensity build-up inside the cavity. Consequently the accuracy and advantage of an absolute internal absorption calibration is not achievable. A room temperature cw QCL was used in a complementary cavity enhanced absorption spectroscopy (CEAS) configuration which was equipped with different cavities of up to ~ 1.3 m length. This spectrometer yielded path lengths of up to 4 km and a noise equivalent absorption down to 4 x 10-8 cm-1Hz-1/2. The corresponding molecular concentration detection limit (e.g. for CH4, N2O and C2H2 at 1303 cm-1/7.66 μm) was generally below 1 x 1010 cm-3 for 1 s integration times and one order of magnitude less for 30 s integration times. The main limiting factor for achieving even higher sensitivity is the residual mode noise of the cavity. Employing a ~ 0.5 m long cavity the achieved sensitivity was good enough for the selective measurement of trace atmospheric constituents at 2.2 mbar.
(A paperback version is published by Logos under ISBN 978-3-8325-2345-9.)
Solifuges (Solifugae, Arachnida) are an important element of the fauna especially in arid and desert environments. Unfortunately, this animal group has only been extremely poorly studied not only in terms of morphology, but also ecology, physiology, systematics and phylogeny. The present study aimed to provide a detailed overview of their anatomy and ultrastructure. Representatives of these peculiar animals were investigated by means of light and electron microscopy in order to gain new insights in their functional morphology and also to evaluate potential characters for their systematic and future phylogenetic studies. The histology and ultrastructure of the following organ systems have been investigated: tarsal structures, sensory structures and nervous system, coxal glands, alimentary system, respiratory system, circulatory system and reproductive systems. Additionally, a camel spider in Baltic amber was described, representing the second known specimen of fossil Solifugae in Baltic amber. Further on, the entire mitochondrial genome of Nothopuga sp. was sequenced for comparison with other solifuges and chelicerates in order to reveal changes in their gene order.
The introduction of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) enabled the separation and visualization of a substantial fraction of an organism’s entire proteome, and when mass spectrometry entered protein science, these proteins became even amenable to identification on a grand scale. Nevertheless, important classes of proteins elude a separation on classical 2 D gels, as the ones showing extremes in isoelectric point or molecular weight, and foremost very hydrophobic proteins naturally embedded in lipid membranes. This thesis aimed at the establishment and adaptation of alternatives to 2-D PAGE. New techniques allowing for an identification and quantification of critical protein classes were designed and adopted to physiological questions in the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. In a comprehensive study on cytoplasmic proteins of S. aureus COL the number of proteins identified by a 2-D gel based approach could be extended by 650 proteins employing gel free technologies. Application of these complementary methods resulted in the establishment of a comprehensive reference map of the cytosolic proteome in growing and non-growing S. aureus cells which can serve as basis for further physiological investigations. Gel free separation of complex protein digests was likewise used in a quantitative study on heat stress in B. subtilis. By implementation of the iTRAQ® technology four different physiological states could be relatively quantified in one experiment. A parallel generation of 2-D gel based data enabled the depiction of strengths and weaknesses of protein quantitation by both, spot intensities on 2-D gels and iTRAQ® signal intensities in MS/MS spectra. Furthermore, new insights into heat sensitivity of pivotal enzymes involved in amino acid biosynthesis could be delivered. The institution of gel free approaches and advancements in 2-D PAGE provide the tools to penetrate into yet unamenable scopes of proteomes. A review on proteome coverage in B. subtilis gives an overview on the strategies which have been explored for most comprehensive protein identification in various sub-proteomes. Although more than one third of B. subtilis’ open reading frames could be demonstrated on protein level, one has to be aware of the fact that it still is a long way to achieve complete coverage of its proteome. Integral membrane proteins make up about one quarter of the entirety of proteins in a cell. Despite their large portion they are clearly understudied due to the intricacy of identification. Their low abundance and non-accessibility of membrane-spanning domains represent major experimental difficulties. The establishment of a protocol efficiently depleting cytosolic proteins by membrane shaving and targeting trans-membrane peptides by novel digestion strategies essentially facilitated identification of highly hydrophobic integral membrane proteins. This protocol was not only successfully applied to the membrane proteome of growing S. aureus cells, but was shown to be applicable in B. subtilis as well. Both studies displayed the novel membrane shaving approach to be highly complementary to a previously established separation of membrane proteins via 1 D PAGE. A combination of the two techniques resulted in identification of about half of the theoretical membrane proteome in both bacteria, and hence layed the foundation for advanced and quantitative analyses. In this regard, 14N/15N metabolically labeled membrane samples of growing and non-growing cells of S. aureus COL were relatively quantified revealing a significant difference in amount for more than one third of the proteins. A corresponding experimental setup was used to compare the membrane proteomes of S. aureus SA113 and its mutant deficient in the lysylphosphatidylglycerol synthetase MprF. Interesting quantitative differences were obtained for proteins most likely involved in the regulation of cellular surface net charge as well as for virulence-associated proteins.
Asymmetrical capacitively coupled RF discharges in oxygen, argon and hydrogen have been experimentally investigated with the innovative technique of the phase resolved optical emission spectroscopy. This diagnostic tool allows to measure spatio-temporally resolved emission intensities of electronically excited species with a high resolution. The spatial (axial) resolution was better than 1 mm and a temporal resolution of about 1.5 ns has been achieved. Therefore the plasma induced optical emission within the RF cycle (TRF = 73.75 ns) from the RF sheath region with a typical mean sheath thickness of about 5mm has been studied. Spatio-temporally resolved optical emission patterns of the following optical transitions have been measured for a total gas pressure in the range of 20 to 100 Pa and self-bias voltages between -50 and -550 V: Oxygen plasma Emission at 777.4 nm and 844.6 nm (atomic oxygen) Argon plasma Emission at about 751 nm and 841 nm (argon) Hydrogen plasma Emission at 656.3nm (atomic hydrogen, H alpha-line) These transitions are the most prominent ones of the investigated excited species in these plasmas as could be shown from overview spectra of the plasma induced optical emission in the range from 350 to 850 nm. For the first time such extensive PROES measurements in oxygen CCRF plasmas are presented in this work. The additional investigations of argon and hydrogen plasmas serve as a reference and for a direct comparison with results from the literature. The temporal behavior of the emission intensity is influenced by the effective lifetime of the emitting states which is on the order of the nanosecond time scale of the RF cycle. Therefore, it does not represent the real temporal behavior of the excitation. A simple method has been applied to calculate relative excitation rates from the measured emission intensities to distinguish different excitation mechanisms and their correct relative temporal behavior. In a close collaboration within the framework of the Sonderforschungsbereich Transregio 24 'Fundamentals of Complex Plasmas' a newly 1d3v PIC-MCC code for simulations of capacitive RF discharges in oxygen has been developed by Matyash et al. The very close coupling of experiment and modeling allowed a really detailed and microscopic understanding of the processes and dynamics from the sheath to the bulk plasma in CCRF discharges. The spatio-temporally resolved excitation rate profiles show four different excitation structures (I-IV). Excitation processes due to the following mechanisms in CCPs could be identified and characterized: I Electrons expelled from growing sheath II Electrons detached from negative ions (collisions with neutrals) + secondary electrons from the electrode surface (ion bombardment) III Field-reversal effect, reduced mobility of electrons (electron-neutral collisions) IV Heavy-particle collisions These excitation mechanisms are characterized by different temporal and spatial behaviors of the excitation rate within the RF cycle. Additionally it has been shown that the excitation by electron impact in the investigated oxygen plasmas results mainly from dissociative electron impact excitation (O2 + e -> O + O* + e) and not from direct electron impact excitation (O + e -> O* + e). Actinometry measurements show that the results are not really credible. Thus actinometry is not applicable on the investigated oxygen RF plasma. A challenge in interpretation is the observed excitation pattern IV. Pattern IV has to be caused in connection with heavy particle collisions nearby the electrode surface and could be observed in all the three plasmas oxygen, argon and hydrogen. It is located directly in front of the powered electrode and appears during almost the whole RF cycle. The temporal modulation is nearly sinusoidal and weak in comparison to the first three patterns. This is due to the weak RF modulation of the ion flux towards the electrode surface which has been proven by a PIC simulation. It could be shown that the modulation degree of pattern IV depends on the transition time of the corresponding positive ions through the RF sheath which is influenced by the ion mass. In oxygen as well as in argon CCRF plasmas pattern IV is less modulated than in hydrogen CCRF plasmas due to the heavier ions in oxygen and argon. Additionally the modulation degree increases with increasing pressure due to the more confined plasma at higher pressures which is yielding in a stronger modulated ion current towards the powered electrode.
The Caribbean is a geologically complex region with several different plate boundary interactions. Geodynamic reconstructions of the northwestern Caribbean region have been particularly controversial in terms of the number of arcs, subduction polarity, and timing of collision. This thesis develops a refined tectonic reconstruction for the northwestern Caribbean based on a review of geological data of Cuba and a regional analysis within the northwestern Caribbean context. With regard to plausibility, significant emphasis was put on the degree and qualitiy of visualization. Three crustal sections across key areas in western, central, and eastern Cuba have been constructed in order to conduct an evolutionary interpretation in three dimensions. Western and central Cuba constitute an orogenic belt resulting from the collision of a mid- to Late Cretaceous volcanic arc - the "Great Caribbean Arc" - with the southern paleomargin of North America. The collision process apparently started in the Campanian, but major north- to northeast-directed thrusting processes at the southern Bahamas margin culminated during the Paleocene. A continous southwest-dipping polarity of the "Great Caribbean Arc", at least from the Aptian-Albian, can be infered from (1) its Late Cretaceous approach towards the North American margin, (2) the magnitude of top to the north directed tectonic transport in the Cuba orogenic belt, and (3) the internal structures of the metamorphic fore-arc assemblages and their evolution on the north side of the arc. An Early Cretaceous southwest-dipping origin of the "Great Caribbean Arc" along the northern fringe of the Chortís Block appears to be in all probability. This concept provides a link between (1) middle Late Cretaceous collision processes along the Matagua suture zone, (2) the Turonian termination of "Great Caribbean Arc"-activity on Jamaica, and (3) the late Campanian onset of collision in the Cuba orogenic belt. The collision of the "Great Caribbean Arc" with the Bahamas margin hampered relative northward motion of the Caribbean Plate from the late Campanian onward. Continued northward push finally resulted in the commencement of north-dipping subduction. Late Cretaceous commencement of north-dipping subduction was accompanied by superposition of oceanic crust and large-scale north-directed gravity sliding on the upper plate, as documented by ophiolitic slide-masses and Maastrichtian olistostromes in eastern Cuba (Nipe - Cristal and Moa Baracoa ophiolite massifs) as well as on Jamaica (ophiolites of the Bath-Dunrobin Complex) and the southern peninsula of Hispaniola. Progress of north-dipping subduction was responsible for the emergence of a Paleocene to Middle Eocene volcanic arc which spanned the northwestern Caribbean along the southern boundary of the Yucatán Basin while the Chortís Block and the Nicaragua Rise were still in a paleoposition to the south of the Maya Block. North-dipping subduction and the associated volcanic arc isolated the Yucatán Basin from its original affiliation to the Caribbean Plate. Relative northward motion of the Caribbean Plate and activity of the Paleogene volcanic arc stopped after the Eocene arrival of thickened oceanic crust of the Caribbean Large Igneous Province at the north-dipping subduction zone. After the late Early Eocene commencement of spreading at the Mid-Cayman Rise, North America - Caribbean relative motion was taken up along the sinistral Oriente Fault with estimated amounts of 800 to 1000 km offset since the Middle Eocene. This transform margin dissmembered the northwestern Caribbean extend of the Paleocene to Middle Eocene volcanic arc. Its eastern bend was uncoupled in the course of this process and may be represented by the Aves Ridge. South-central Hispaniola can be restored to a Middle Eocene position to the south of eastern Cuba, which accounts for an approximate Cenozoic displacement of 200 to 300 km. Therefore, most of the western prolongation of the Oriente Fault must be accommodated at the northern bounding-faults of the southern peninsula of Hispaniola. The proposed synthesis is in clear accordance with the paradigm of plate tectonics, corroborating its capability to incorporate even a complex region like the Caribbean.
In the present work, mass determinations of the eleven neutron-deficient nuclides (99-109)Cd, of ten neutron-rich silver nuclides (112-114,121,123)Ag, and seven neutron-rich cadmium nuclides (114,120,122-124,126,128)Cd are reported. Due to the clean production of the neutron-deficient nuclides it was possible to reduce the experimental uncertainties down to 2 keV, whereas the measurements of neutron-rich nuclides were hampered by the presence of contaminations from more stable In and Cs nuclides. In the case of 99Cd and 123Ag the masses were determined for the first time and for the other nuclides the mass uncertainties could be reduced by up to a factor of 50 as in the case of 100Cd. In the case of a potential isomeric mixture as for (115,117,119)Ag and 123Cd, where no assignment to either the ground state or the excited state was possible, the experimental results were adjusted accordingly. Afterwards all results were included in the framework of the atomic-mass evaluation and thus linked and compared with other experimental data. In the case of the neutron-deficient Cd nuclides a conflict between the mass values obtained in the present work and those published by the JYFLTRAP group could be solved by performing an atomic-mass evaluation. These mass measurements are an important step towards an understanding of the physics of the rp process that will enable a more reliable determination of the composition of the produced material at A = 99. It has been shown that the mass of 99Cd strongly affects the A = 99 production in an X-ray burst model, and that uncertainties have been significantly reduced from more than an order of magnitude to about a factor of 3. The dominant source of uncertainty is now the mass of 100In. In principle, other uncertainties will also contribute. These include those of masses of lighter Cd isotopes, where similar rp-process branchpoints occur and which might affect feeding into the 99Cd branchpoint. In addition, nuclear reaction rate uncertainties will also play a role. However, as reaction rates affect branchings in a linear fashion, while mass differences enter exponentially, mass uncertainties will tend to dominate. Also, which reaction rates are important depends largely on nuclear masses. For example, for low Sp(100In) a (p,γ)-(γ,p) equilibrium will be established between 99Cd and 100In and the 100In(p,γ) reaction rate would affect the A = 99 production, while for larger Sp(100In) the 99Cd(p,γ) reaction rate might be more relevant. Therefore, the mass uncertainties should be addressed first. The presented results are relevant for any rp-process scenario with a reaction flow through the 99Cd region. Here, an X-ray burst model has been used to investigate in detail the impact of the present measurements on such an rp process. The νp process in core collapse supernovae might be another possible scenario for an rp process in the 99Cd region. It it is planed to also explore whether in that case mass uncertainties have a similar impact on the final composition. On the neutron-rich side of the valley of stability for the Cd and Ag chains of nuclides, the r process has not yet been reached. Further technical development on suppression of contaminants are required. This includes improvements on the ISOLDE side, e.g., by improving the selectivity of the transfer line or on the ISOLTRAP setup by implementing an electrostatic ion beam trap for a fast and efficient isobaric selection. Nevertheless the obtained results contribute to the knowledge of nuclear structure. The trends in the two-neutron separation-energy S2n and the interaction between the last neutrons and last protons ΔVpn were corrected to more smooth evolutions, as already seen in other regions of the nuclear chart. The strongest corrections have been observed for even-N nuclides, were more new experimental data are available. Thus, new measurements on odd-N nuclides are suggested. This also is underlined by the trends observed in the Garvey-Kelson relations for the neutron-rich Cd nuclides. Furthermore, it has been shown, that the prominent structure of the ΔVpn for an entire chain of nuclides including inflexion points can be reproduced by using simple relations between quantum numbers of the occupied orbits. This approach connects ten values for each nuclide with only one adjusted parameter. This has been investigated for 63 ΔVpn values of even-even nuclides in the vicinity of Z = 50 and 50 ≤ N ≤ 82. The simple model works remarkably well for the elements Cd, Sn, and Te. Small deviation have been observed for the Xe and Pd nuclides which were explained with the limitations of the model to the vicinity of the close shells, where the nuclides have only few valence protons and neutrons.
Therapeutic Sealing of Proximal Tooth Surfaces: Two-Year Clinical and Radiographic Evaluation
(2009)
The diagnosis, prevention and treatment of proximal carious lesions comprise a constant problem in clinical dentistry. The purpose of this investigation was to test the safety and clinical effect of a new treatment for proximal caries. In 50 patients with two proximal initial lesions (D1-3 without cavitation, bitewing X-ray), orthodontic rubber rings were applied to gain access to the interproximal space. One of the lesions was sealed with a thin polyurethane-dimethacrylate foil using a bonding agent (Heliobond®, Vivadent, Schaan/Liechtenstein); the other lesion received oral home-care with dental floss and fluoridated toothpaste and was left as control. In clinical follow-ups after 6 and 12 months and X-ray evaluation after two years, clinical retention of proximal tape and the underlying sealant, marginal adaptation, discoloration, tooth vitality, proximal plaque and gingivitis were checked. In addition, caries was assessed clinically and radiographically. The sealants showed good retention, marginal adaptation and colour. After two years, vitality of all teeth was still positive and no relevant differences in plaque accumulation or gingival status were found between sealed and control teeth. Two sealed surface had to be filled due to caries progression (D3 with cavitation). 9 sealed lesions showed caries regression. In contrast, only 4 control lesions regressed and also two showed progression. The loss of tape had no significant influence on the lesion progression indicating the effect of the underlying bond. All other sealants and control lesions were stable indicating an arrest of the lesion. In conclusion, sealing initial proximal lesions showed no clinical problems and mostly arrest of initial carious lesions on bitewing X-rays.
The experimental determination of the electron energy distribution of a low pressure glow discharge in neon from emission spectroscopic data has been demonstrated. The method extends an approach by Fischer and Dose [5]. The spectral data were obtained with a simple overview spectrometer and analyzed using a strict probabilistic, Bayesian data analysis. It is this Integrated Data Analysis (IDA) approach, which allows the significant extraction of non-thermal properties of the electron energy distribution function (EEDF). The results bear potential as a non-invasive alternative to probe measurements. This allows the investigation of spatially inhomogeneous plasmas (gradient length smaller than typical probe sheath dimensions) and plasmas with reactive constituents. The diagnostic of reactive plasmas is an important practical application, needed e.g. for the monitoring and control of process plasmas. Moreover, the experimental validation of probe theories for magnetized plasmas as a long-standing topic in plasma diagnostics could be addressed by the spectroscopic method.
Effect of surgical intervention on the activation status of circulating monocytes and T-cells
(2009)
Major surgery causes alterations in immune function which results in immune suppression in post surgical patients. Deactivation of monocytes in these patients is characterised by the reduced ability of these cells to produce pro-inflammatory cytokines on stimulation with LPS in vitro and by markedly reduced HLA-DR expression. Immune suppression in patients with systemic inflammation has also been associated with a high level of apoptosis in both the circulating T and B cell populations. In addition post surgical T cells have a reduced capacity to proliferate ex vivo in response to co-ligation of the T cell receptor and CD-28. Considering these impairments of immune system, this study aimed to define the extent of immune modulation in both innate and adaptive system in a cohort of surgical patients. Measurment of the level of HLA-DR expression of monocytes in these patients showed a considerable change in monocyte phenotype in the immediate post operative period. In line with previous work, all patients showed a considerable reduction in monocytic surface HLA-DR expression which persisted for many hours and those who had post surgical septic complications showed the most severe reduction. Importantly, patients with minor surgical intervention also exhibited decreased HLA-DR expression. Gene expression analysis of monocyte in these patients showed the up-regulated transcripts of genes involved in extravasation and realignment of the cytoskeleton. Analysis of periperal T cell demonstrated a significant reduction in their number in the circulation and a sharp raise in the number of apoptotic T –cells in the immediate post surgical period. Microarray analysis of T cells from patients who developed sepsis and patients with an uneventful recovery within the post-operative period (3 days) showed a substantial reduction in the transcriptional activity of many genes in both groups. However, this down regulation of T cell transcriptional activity appears to be a rather broad and non specific effect since it is not restricted to particular functional pathways. Real time PCR analysis of both the CD4+ and CD8+ populations using selected down-regulated genes showed that the change in transcriptional profile is equally evident both in CD4+ and CD8+ T-cells. The cause of this transient immune depression following surgery remains to be established and it may represent an important enabling factor which contributes to the development of post surgical infections and inflammatory complications.