| Title | Synthese von Chlorinen mit annellierten Lactamringen als Untereinheiten für künstliche Photosynthese-Modellsysteme |
| Author or Creator | Haake, Elmar |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | Photosynthetic-Reaction-Center-Modelsystem,Cyclohept-4-enopyrrole, 5-Formyl-2-cyanopyrrole Nitrile Aldehyde, Ketal-Cleavage, Beckmann-Rearrangement |
| Description | The dissertation subsumes to the actual photosynthetic research, which is engaged in discussions about details of biological photosynthetic processes. At the present time the synthesis of artificial modelsystems is aimed to abstract functional and structural aspects of natural photosynthetic-reaction center. These modelsystems allow investigations of processes under defined conditions. The dissertation describes the synthesis of chlorines with annellated lactame rings from cyclohept-4-enone and pyrrolic building blocks, which should be used as potential subunits for artificial photosynthtetic-reactioncenters. On attemps to synthesize differrent pyrrolic chlorin prebuilding blocks the synthesis of 5-formyl-2-cyanopyrrole was evolved. After linkage of this pyrrolic building block with an ABC-tricycle the cyclisation to chlorins containing an annellated ring were successful. After cleavage of a protecting group the chlorines underwent Beckmann-rearrangement which delivers chlorines with annellated lactame rings as potential subunits for photosynthetic-modelsystems. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000028.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000289 |
| Title | Messungen von Peroxyradikalen in unterschiedlichen Luftgebieten |
| Author or Creator | Behmann, Thomas |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | peroxy radicals; free radicals; tropospheric ozone; chemical amplification; fieldvoc; price |
| Description | Peroxy Radicals have been measured in different regions in Europe. These different environmentsare characterized by mean or moderate anthropogenic impacts at the lower atmosphere(troposphere). Measurements were performed during the projects FIELDVOC and OCTA in 1993and 1994. The aim of these projects is an improved investigation of tropospheric ozone generation.The first measurements during both campaigns in 1993 were performed using an instrument, whichwas developed at the Max-Planck-Institut für Chmie (Mainz). For the measurements in 1994 theinstrument and the calibration method was improved for operation during field campaigns. Themeasured data are compared with results of a photochemical model to identify the role of Non-Methane-Hydrocarbons and to determine local ozone production. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000031.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000317 |
| Title | Strahlungstransport und Inversions-Algorithmen zur Ableitung atmosphaerischer Spurengasinformationen aus Erdfernerkundungsmessungen in Nadirgeometrie im ultravioletten bis nahinfraroten Spektralbereich am Beispiel SCIAMACHY |
| Author or Creator | Buchwitz, Michael |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | remote sensing, radiative transfer, inversion algorithm, correlated-k distribution method, ESFT, SCIAMACHY, GOME, DOAS, climate change |
| Description | Retrieval of atmospheric constituents from remote sensing measurements requires a radiative transfer forward model and appropriate inversion algorithms. A fast and accurate correlated-k (c-k) distribution radiative transfer scheme has been developed for the simulation of radiance spectra to be measured in nadir viewing geometry by the SCIAMACHY satellite diode array grating spectrometer. SCIAMACHY is part of the atmospheric sciences payload of the European Space Agencies ENVISAT-1 satellite to be launched in mid 2001. SCIAMACHY covers the spectral region 240-2385 nm with moderate spectral resolution (0.2-1.6 nm FWHM) and observers solar radiation scattered and reflected back to space by the Earths atmosphere and surface. The spectral region 440-2385 nm is dominated by molecular line absorption due to CO, CO2, CH4, H2O, N2O, and O2. The most accurate approach for the calculation of the spectrally averaged radiance - if line absorption needs to be considered - is the line-by-line approach. This approach, however, is very time consuming and can only be used for reference purposes. Therefore, a much faster c-k scheme has been developed. It is based on parameters that can be interpreted as trace gas absorption cross-sections representative for narrows spectral intervals. In this context a new method (alpha-mixing scheme) has been developed to consider spectrally overlapping line absorption. This method is shown to be more accurate (at SCIAMACHY resolution) and flexiblethan any previously developed method. The c-k and a line-by-line schemes have been implemented in the radiative transfer. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000033.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000338 |
| Title | Bestimmung von Verweilzeiten und Transportraten in der Warmwassersphaere des Suedatlantiks aus Tracerdaten |
| Author or Creator | Butzin, Martin |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | oceanography, South Atlantic, water masses, Central Water, age, dating, subduction, transport, tracer, tritium, isotopes, CFC´s, hydrologic cycle |
| Description | Tritium and CFC-11 data obtained from the programmes WOCE (1990-1995) and SAVE (1987-1989, CFC-11 data only) are used for an analysis of the upper level circulation in the South Atlantic Ocean (density range sigma-0 = 26.0-27.1 kg/m**3). A new bomb tritium input function for the South Atlantic is presented. The atmospheric deposition is based on previous work by Doney et al. [1992]. The new input function also accounts for tritium deposition due to river runoff and for tritium exchange with other ocean basins. The calculated total tritium input for 1960-1995 between 0°S-50°S and the observed tritium inventory in 1995 agree well (within 1%). This agreement supports a value of 0.70 for the liquid/vapor isotopic fractionation factor of tritium, disproving GCM model calculations by Koster et al. [1989] that yielded a fractionation factor of 0.35. Tritium surface water concentrations are inferred from a simple mixed layer model driven by atmospheric tritium fluxes and calibrated using GEOSECS and WOCE data. The surface water concentrations of the South Atlantic are lower than in the North Atlantic. The highest surface values in the 1990´s are found in the subtropics where the surface water concentrations are still slowly increasing. As boundary condition for CFC-11 it is assumed that the sea surface is in a solubility equilibrium with the atmosphere. For quasi synoptic analyses the tritium and CFC-11 data are projected to the year 1993 using a 1D advection-diffusion model. Meridional sections show tracer concentrations decreasing with depth. Maximum penetration of tritium and CFC-11 is found in the subtropical region. North of about 20°S there is a concentration decline in both tracers indicating upwelling processes. Distributions on isopycnal surfaces show high tritium values in the western South Atlantic which may be due to the formation of Subtropical and Subantarctic Mode Waters. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000034.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000340 |
| Title | Ein Inversmodell fuer den Suedatlantik mit der Methode der finiten Elemente |
| Author or Creator | Dobrindt, Uwe |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | finite elements, inverse model, adjoint method, advection-diffusion problem, oceanography, South Atlantic, unstructured mesh, large-scale circulation |
| Description | The large scale flow field of the South Atlantic and its associated heat and fresh water budget are studied with an inverse model. The model relies on traditional assumptions of mass, heat and salt conservation. A 3-dimensional velocity field which is in steady state and obeys geostrophy is derived. Using this flow field, the steady state advective-diffusive equations for temperature and salinity are solved and the corresponding density is calculated. An optimization approach is used that adjusts reference velocities such that modeled temperature and salinity are close to observations and that velocities are in geostrophic balance with the modeled density field. In order to allow for a variable spatial resolution, the finite element method is used. Its mesh is totally unstructured and the 3-dimensional elements are tetrahedra. Climatological hydrographic data, observations of sea surface height (SSH) from satellite altimetry and wind data are assimilated in the model. The advantages of the finite element method make it possible to use an easy representation of the model parameters on the tetrahedra. It is not difficult to find the adjoint form of the discrete equations. The unstructured mesh agrees well with the complex geometry of bottom topography. The model results show, that the reference velocities return the structure of the SSH data. In general the upper-level circulation corresponds to the circulation known from the literature. The volume transport through Drake Passage is constrained to be 130 Sv. At the open boundaries (Drake Passage, 30S, 20E) the mass, heat and salt transports are in agreement with the literature. This is also true for the transports of surface, intermediate, deep and bottom water.9.6 Sv of bottom water is formed in the South Atlantic. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000035.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000352 |
| Title | Selektive Totalsynthese von Chlorinen mit annellierten Chinonen zur Untersuchung des Symmetrieeinflusses auf den Lichtinduzierten Elektronentransfer |
| Author or Creator | Abel, Yvonne |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | Chlorin-Quinone Dyades, Light Induced Electron Transfer, Symmetry Effects, Chlorin Total Synthesis, Synthesis of Pyrroles bearing Quinone Moities |
| Description | Um den Einfluss von Symmetrieeffekten auf den lichtinduzierten Elektronentransfer zu untersuchen, wurden zwei unterschiedlich mit Chinonstrukturen annellierte Chlorine als Donor-Akzeptor-Modellsysteme synthetisiert. Das Chinon ist entweder entlang der x-Achse orientiert, welche den gesaettigten und den diesem gegenueberliegenden Ring durschschneidet oder entlang der y-Achse, so dass das Chinon benachbart zum gesaettigten Ring lokalisiert ist, Im Rahmen dieser Dissertation konnte ein totalsynthetischer Zugang zu den angestrebten Chlorin-Chinon-Diaden in 12 bzw.17 Reaktionsschritten erarbeitet werden. Die zur Untersuchung von Symmetrieeinfluessen auf den lichtinduzierten Elektronentransfer notwendigen Substitutionsmuster beider Diaden wurden im Verlauf der Synthese durch den Einbau der entsprechenden, bereits die Chinonuntereinheit tragenden Pyrrolbausteine erhalten.Letztere konnten ausgehend von Naphthochinon aus einfachen Grundchemikalien aufgebaut werden.In order to investigate the effect of the molecular symmetry on the light induced electron transfer in chlorin-quinone dyades two chlorin-quinone donor-acceptor model systems were synthesized. The quinone is either be orientated along the x-axis, by which the chlorin is intersected at the reduced ring and the opposite ring or along the y-axis, so that the quinone ist located adjacent to the reduced ring. The target donor-acceptor systems could be obtained according to a general synthetic approach which was developed for the synthesis of chlorins and corrins. The concept of this ynthesis requires altogether four monocyclic building blocks. A new synthetic pathway was developed for the preparation of the pyrrole rings bearing the quinone moieties. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000036.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000367 |
| Title | Untersuchungen zum Verhalten von insektizidhaltigen Waessern bei Prozessen der chemischen Nassoxidation |
| Author or Creator | Bernecker, Axel |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | AOP, biochemical degradation, Daphnia-Test, Imidacloprid,insecticides, lumination-bacteria-Test, Ozone, Photocatalysis, Pirimicarb, Titandioxide |
| Description | The aim of the present work was the investigation of the behavior of insecticide-containing water in different wet-oxidation-processes. As model pollutants the insecticides pirimicarb and imidacloprid were selected. Destination of these investigations was the optimization of the process influencing parameters like temperature, pH-value and added concentration of oxidizing agent and/or catalyst. It could be shown, that under laboratory conditions the utilization of the different oxidation processes, the - photolytical oxidation with ultraviolet light and hydrogen peroxide, - photolytical oxidation with ultraviolet light and ozone - photocatalysis with ultraviolet light and titanium oxide, leads to a degradation of both insecticides. The evaluation of the performed toxicity tests shows that in the luminescent bacteria test for both pesticides before and after treatment no inhibition of the light intensity occurred. In the Daphnia tests however it was shown that in the case of pirimicarb the toxicity towards Daphnia mobility decreases during all irradiation experiments. In the case of imidacloprid it was shown that the with hydrogen peroxide photolytically treated samples are all on the same toxic level. In the case of the with ozone photolytically and the photocatalytically treated samples of imidacloprid the toxicity increases in the first phase of treatment. At the end of the experiments the toxicity against Daphnia was reduced below the initial value of toxicity of imidacloprid. The evaluation of the biochemical degradation, expressed by the quotient of the biological- and the chemical oxygen demand, shows, that for both pesticides for all three applications an improvement could be achieved. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000038.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000384 |
| Title | Schnelle 1H-NMR-spektroskopische Bildgebung mittels angepasster Phasenkodierung der chemischen Verschiebung |
| Author or Creator | Ebel, Andreas |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | nuclear magnetic resonance, NMR, spectroscopic imaging, proton MRSI, chemical shift,U-FLARE, rat brain, in vivo |
| Description | The minimum total measuring time T is a crucial parameter for the clinical application of a1H NMR spectroscopic imaging (SI) experiment. To keep it as short as possible is not onlyfor the benefit of the patient, but is also necessary to suppress motion artifacts in thespectroscopic images. In this thesis, Adjusted Chemical Shift Phase Encoding (APE) hasbeen developed as an alternative to the phase encoding scheme used conventionally forspectroscopic U-FLARE, which aims at FFT reconstruction of NMR spectra. For APE,advantage is taken of the fact that often the number of strong resonances K is considerablysmaller than the number of conventional phase encoding steps N. Systematic descriptionand analysis of the NMR signal acquired using the ``constant time´´ encoding scheme leadsto a system of linear equations. Provided that N >= K, this can be solved in the leastsquares sense by exploiting prior knowledge about all resonance frequencies with onlyminor restrictions regarding the choice of encoding times. Thus, the minimum totalmeasuring time, which is proporional to N can be reduced such that an extension ofspectroscopic U-FLARE towards a fast 3D SI method becomes feasible. APE providessimilar signal-to-noise-ratio per unit measuring time as the conventional procedure and hasallowed a reduction of T in recent experiments by a factor of 4. APE lends itself not only toapplications of 1H NMR SI on clinical whole-body scanners, but also to 2D NMRspectroscopic experiments. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000039.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000395 |
| Title | Verwendung einer neuartigen Ringschlussreaktion zur Totalsynthese von Chlorin-Fulleren- und Chlorin-Chinon-Dyaden als Modellsysteme fuer die Photosynthese |
| Author or Creator | Kutzki, Olaf |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | chlorin total synthesis, porphyrinoids, artificial photosynthesis, light induced electron transfer, heterocyclic o-quinodimethanes, chlorin-fullerene dyad, chlorin-quinone dyad |
| Description | The aim of this dissertation was the total synthesis of model compounds for an elementary step of photosynthesis, the light induced charge separation. In contrast to many known model systems in literature, in which porphyrins have been used as electron donors, the donor used in this case was the chromophore of the naturally photosynthetic pigments, a chlorin derivative (dihydroporphyrine). As an electron acceptor a fullerene C60 has been used, which is known to be an excellent electron and energy acceptor since a few years. Another acceptor, which has been used was a quinone, which serves also as an acceptor in the naturally photosynthetic systems. Based on a model synthesis a total synthetic approach to a chlorin derivative with an anellated sulfolene ring could be achieved. This chlorin derivative, which is a precursor for a dimethylene chlorin (heterocyclic o-quinodimethane), could be used for many functionalisations by Diels-Alder reactions. Further a new ring closure method has been developed which has some advantages in preparative use. This new ring closure method involves a thermic cyclization of a carboethoxy-substituted hydrobiline derivative to the corresponding chlorin macrocycle. The cyclization is part of a cascade of reactions during which also the dienophile like fullerene C60 or quinone is covalently linked to the chlorin framework by a Diels-Alder reaction. This led to the desired dyads, in which the luminescence is quenched, which indicates an intramolecular transfer of electrons or energy from the chlorin moiety to the acceptor moiety. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000040.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000403 |
| Title | Untersuchung von Ionen-Molekuel- und Ion-Ion-Reaktionen mit einem Ionen Cyclotron Resonanz Massenspektrometer |
| Author or Creator | Malek, Robert |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | FT/MS ICR Ion Cyclotron Resonance Mass Spectrometry Gallium(III)Chloride Hexachlorobenzene Ion/Ion - Reactions Ion/Molecule - Reactions Trajectory Calculation Ion Traps |
| Description | The fundamentals of simultaneous trapping of positive and negative ions in a static electromagnetic trap are described. A typical application of this type of traps is ion cyclotron resonance mass spectrometry (ICR-MS). Analytical expressions for the potentials of common traps are derived, and used to study the dynamics of simultaneously stored positive and negative ions. The theory of motion of ions in ICR-Traps is expanded to deal with simultaneously trapped positive and negative ions. The proper frequencies of stored ions in the field are calculated to the high accuracy needed for precise mass measurements. The predictions for common magnetical traps are improved too. The theory of the duffing oszillator is applied to the motion of ions in a special trap for simultaneous storage of positive and negative ions. Possibilities for ion manipulation are derived. Corresponding experiments verify the predictions about proper frequencies of ions. A new ICR-cell for simultaneous storage of positive and negative ions is studied in detail. The new experimental methods are applied to the study of inert gases, gallium(III)chloride and hexachlorobenzene. Cooling of charged particles by oppositely charged ions is observed, as well as increased speed of reactions with negative ions. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000041.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000411 |
| Title | Selektive Synthese von neuartigen Chlorinen für die Photodynamische Therapie |
| Author or Creator | Pont, Francesc |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | Chlorin-Horse-raddish-Peroxidase-Model-oxidation, Mamma-Carcinome, Breast-Cancer, Estrogen-Receptor, Photosensibilisator, Chlorin-Estrogenderivative, Krownether-Chlorin |
| Description | From Deuteroporphyrin through partial synthesis derived chlorins were taken in this work as starting products for the synthesis of regioisomeric formylchlorins, crown ether- and estron-chlorin adducts. The cis- trans- stereoisomeric chlorins can be through appropriate protonating conditions interconverted. The difference in the bathochromic shift of the UV/Vis bands of the formylchlorins were investigated and qualitatively interpreted on the basis of similar in the literature described phenomena. The binding through esterification of an enantiomeric estron derivative to the propionic side chains of a racemic chlorin yields two through open column chromatography separable optical active diastereomers which can be deployed as fluorescence pigments and photosensibilisators for the tumor detection and/or destruction. The binding through amidation of crown ether to the propionic side chains of a chlorin produce derivatives which could be of interest for a variety of host-guest relations concerning molecular recognition and catalysis. The last part of the work deals with the novel enzymatic and catalytic oxidation of deuteroporphyrin to chlorins and oxochlorins which should carry significant consequences for the biosynthesis and synthesis of similar natural hydroporphyrins. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000042.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000421 |
| Title | Synthese von Porphyrin- und Chlorinderivaten zur Immobilisierung auf Elektrodenoberflächen und Darstellung von Porphyrin-Fulleren-Dyaden |
| Author or Creator | Wedel, Michael |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Immobilisierung, Elektropolymerisation, Oberflaechenkoordination,Dyade, Gold, Titandioxid, Glaskohleelektrode, Cyclovoltammetrie,Epoxidierung, Sensor, Bingel-Reaktion |
| Description | This work describes on the one hand the synthesis of porphyrin and chlorin derivatives for the immobilization on electrode surfaces and on the other hand the synthesis of porphyrin fullerene dyads. In all syntheses hemin was used as the educt. The electrode surfaces were titanium dioxide, carbon and gold. The immobilization on titanium dioxide and gold was done by a surface coordination process of phosphonic acid side chains and disulfide groups. The immobilization on glassy carbon electrodes was achieved by electropolymerization of pyrrole groups. An important aspect of this work was the incorporation of different metal ions (iron, manganese and cobalt) into the macrocycles. The metal ions could then be reduced and oxidized by cyclovoltammetry. The modified electrodes were used as sensor for cyanide and alkyl halides. In the same way an epoxidation of ethylene with atmospheric oxygen was possible. The porphyrin fullerene dyads were synthesized for the investigation of the photosynthetic primary step, namely the light induced charge separation. The fullerene was attached via a Bingel reaction to the porphyrin. UV/Vis and luminescence measurements indicated no interaction in the ground state but an almost quantitative luminescence quenching in the excited state. Photophysical measurements showed that this is due to an electron transfer from the donor to the acceptor with a lifetime of the charge separated state of 5.2 ns. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000043.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000430 |
| Title | Entwicklung eines Nachweisverfahrens für gentechnische Veraenderungen im Genom von Mikroorganismen aus Starter- und Schutzkulturen |
| Author or Creator | Käse, Mario |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | genetic, engineering, modified, modification, microorganisms, GMO, detection, novel,food, RDA, 2D-PAGE, starter, subtractive, hybridization, Lactobacillus,Lactobacteriaceae, Penicillium |
| Description | In this work a system for the detection of genetically modified microorganisms is presented, that may be applied for an all-purpose, resp. non-specific identification of starter and protective cultures, which are modified by means of genetic engineering.The detection system is based on an equalization of the genome of the strain, that might be genetically modified with the genome of a near relative reference-strain, which is not genetically modified. For that purpose Representational Difference Analysis (RDA) is used, a combination of subtractive hybridisation and suppression PCR. The generated strain-specific DNA fragments are isolated by two-dimensional polyacrylamide gelelectrophoresis. Their DNA sequences are compared with resources of DNA data banks. The detection system was developed and proved using the model organisms Lactobacillus sake and Penicillium nalgiovense. It is suitable for the examination of all microorganisms, which are applied for the processing and conservation of foods. The method permits the detection of genetically modified microorganisms on condition that they contain two or three genetic elements from foreign species. Its main advantage: there is no necessity of knowledge about the DNA sequences of the foreign genetic elements. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000045.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000450 |
| Title | Bakterielle Besiedlungsmuster unter Huminstoff-Einfluss in Grundwasser-Simulationsfiltern |
| Author or Creator | Koch, Thomas |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | round-Water Humic-Substances Bacterial-Diversity Bacterial-Colonisation-Patterns in-vitro-Activity Clusteranalysis Acid-Hydrolysis BDOC LC-DOC Py-FIMS DGGE SEM |
| Description | The object of the following examinations was to find an explanation which role humic substances (HS) play within the process of bacterial colonisation in ground water and how their influence it. For long-term investigations a batch-reactor which simulate a ground water biotop was developed. More than 800 strains were isolated as pure cultures and 600 thereof examined according to their morphological, physiological, chemotaxonomical and genomic properties. Transformations of the HS were detected by acid-hydrolysis, LC-DOC-Detection and pyrolysis-fieldionisation-mass-spectrometrie. The scanning-electron-microscopie SEM was used to discribe the formation of the biofilm.In summary the following results were prooved:- The communities of the reactors as well as most of the isolated strains were able to use the HS as a sole carbon and energy source. - The HS led to decline in the diversty patterns.- The the isolated strains of the ground water showed a higher physiological activity than those isolated from the reactors.- Drastic changes occured according to the morphological and physiological properties of the isolated strains.- The influence of the HS on the diversity and colonisation patterns were stronger in the aquatic phase.- The communities were dominated by only a few species.- Bacterial transformations on the HS were proved by acid hydrolysis, LC-DOC and Py-FIMS without clear similarities in the results of this three methods.- REM images showed no differences according to the biofilm in both reactors. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000046.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000464 |
| Title | Methodenvergleich und Methodenentwicklung zur Loesung der Bewertungsproblematik in produktbezogenen Oekobilanzen |
| Author or Creator | Stahl, Beate |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | life cycle assessment, impact assessment, normalisation, valuation, weighting, sustainable development, distance-to-target, population surveys, expert surveys, delphi-technique |
| Description | Die Grundstruktur von Ökobilanzen (Zieldefinition, Sachbilanz, Wirkungsabschaetzung mitBewertung und Interpretation) ist das Ergebnis nationaler und internationaler Bemühungenzur Vereinheitlichung der Durchführung von Oekobilanzen (ISO 14040). Für den TeilBewertung, in der Sachinformationen mit Werturteilen verbunden werden müssen, wurdenach Analyse vorhandener Methoden eine Vorgehensweise entwickelt, in der die Ergebnisseder Wirkungsanalyse mit der Gesamtbelastung einzelner Wirkkategorien (Normalisierung) undder Gewichtung der Umweltproblemfelder (z. B. Treibhauseffekt, Ozonzerstörung,Versauerung etc.) verknüpft werden. Dabei werden fuer die Ableitung von Gewichtungenunterschiedliche Ansätze (Sustainable Development, politische Ziele,Bevölkerungsumfragen, Expertenumfrage) verfolgt. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000047.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000470 |
| Title | Diskussion vor verschlossener Tür: Auseinandersetzungen zur Europa-Ideologie in der Türkei im Zusammenhang mit dem Antrag auf Beitritt zur EG 1986-1987 |
| Author or Creator | Atakli, Ibrahim |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | Tuerkei; Assoziierungsabkommen; EU-Beitritt; Hindernisse, politische ForderungenEuropas; Minderheiten- und Menschenrechte; Demokratisierung und Kurdenfrage;tuerkische Medien |
| Description | Der EU-Beitritt ist ein zentrales aussenpolitisches Interesse der Tuerkei. Die Debatte, die in der Tuerkei in diesem Zusammenhang um die Frage des Beitritts gefuehrt wurde, orientiert sich nach politischen Stroemungen, die Kemalisten und die Islamisten. Die untersuchten Zeitungen vertreten in der Minderheitenfrage die tuerkische Nationalitaetenpolitik und betrachten die Forderungen Europas als eine Einmischung in die inneren nationalen Angelegenheiten. Auch im Bereich der Aussenbeziehungen vertreten sie die Interessenpolitik des Staates. Eigene Recherche, Analysen und Hintergrundinformationen zur behandelten Frage fehlen in den Zeitungen so gut wie vollstaendig - das Darstellungsmittel sind fast ausschliesslich Interviews - die Politik wird personalisiert.The EC-joining is a central foreign political concern of Turkey. The debate, which is carried on in Turkey in connection to the joining-proposal, looks about the political streamings, the kemalists and the islamists. The studied magazines take in the minority discussion the view of the turkish nationality politics and regard the receivables of europe as an intervention to the internal affairs. in the section of the foreign poltics they take the view of the official political interests. The own recherches, analysts andbackground informations to the treated question are absent in the magazines nearly complete - the working methods are hardly exclusive interviews - the politic is personalised. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000048.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000480 |
| Title | Von der Umwelterziehung zu ganzheitlicher Bildung als Ausdruck integralen Bewusstseins |
| Author or Creator | Möhring, Martin |
| Language | ger |
| Date | 1996 |
| Subject and Keywords | Umwelterziehung, Umweltbildung, Bewusstsein, Esoterik, Unterricht, Unterrichtsmaterial, ganzheitlich, Environmental-Education, Esoterics, Education, School-Education, Educational-Material, holistic |
| Description | Dieses Buch zeigt eine ganzheitliche Sichtweise fuer die Umweltbildung auf, die den technologisch erzeugten Dualismus ueberwinden und mitweltbewusstes Handeln anregen kann. Es geht um die Entfaltung des Integralen Bewusstseins, wobei an Theorien von Gebser, Maturana, Capra, Preuss u.a. angeknuepft wird und diese auf die Umwelt- bzw. Mitweltbildung bezogen werden. Eine grundlegend von vorherrschenden Denkweisen unterschiedliche Betrachtung wird dazu bei Robert Fritz gefunden, der zeigt, wie anstelle einer nur reagierenden Haltung eine wirklich kreative in den Vordergrund ruecken kann, die die Strukturen unseres Lebensbestimmt. Fuer eine ganzheitliche Bildung und ensprechende unterrichtliche Konzepte bedeutet dies, alle Bewusstseinsstrukturen der Lernenden zu beruecksichtigen. Die herkoemmliche, bloss das mental-rationale Bewusstsein ansprechende Unterrichtspraxis sollte durch erleb- und erfahrbare Elemente etwa gemaess der humanistischen Psychologie erweitert werden. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000049.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000494 |
| Title | Theory and Numeric of Spectral Value Sets |
| Author or Creator | Gallestey Alvarez, Eduardo |
| Language | eng |
| Date | 1998 |
| Subject and Keywords | spectra, pseudospectra, spectral-value-sets, stability-radius, operator-theory, robustness-analysis, spectral-approximation, delay-systems, hydrodynamical-stability |
| Description | Spectral value sets are useful in studying how the spectrum of closed linear operators on infinite dimensional spaces change under the effect of perturbations. They are also important in investigations related to the transient behaviour of linear systems driven by non-normal operators. In the thesis we show that the spectral value sets that can be achieved by perturbations of a given level can be characterized in terms of the norm of certain transfer function. Furthermore, we present an algorithm able to efficiently calculate these sets in the matrix case. In the general (operator!) case finite dimensional approximations of the corresponding transfer function are the natural approach. Thus, we state the approximation problem and solve it under certain conditions. Finally, we apply our approximation results to the robustness analysis of delay equations and of the Orr-Sommerfeld operator. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000050.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000502 |
| Title | Definition, Teilimplementation und Verifikation eines vollautomatischen Vermittlungssystems für den Personentransport |
| Author or Creator | Zegartowski, Lutz |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | routematching, ridesharing, mediation carsharing simulation, ´´public transport,´´ automatic implementation, roadmap modelling computer science |
| Description | The PeopleLogistic CORONA, developed in the Institute of Transport and Computer Science, is a complex simulation system for traffic, an analysing tool and also a real-time mediation system for a large population. CORONA mediates routes local, regional and countrywide finding the minimum of vehicle miles travelled. The strategy used is to come to high occupancy vehicles in the means of the Lean Transport. High occupancy vehicles results in reduced traffic load. Supplier of transport (public transport and rideshares) are organized in the system in a way that leads to a higher (or at least stable) mobility with less traffic. CORONA is in a first way a full automatic routefinding system using real distances from door to door. These routes are mediated with the supplied routes in an optimized way. It is possible to perform hic-et-nunc-simulations for predicting possible reductions and mediation success for each city or region individually. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000051.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000516 |
| Title | Ionentransporte in C6-Glioma-Zellen bei oxidativem Streß |
| Author or Creator | Düßmann, Heiko |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | spectroscopy, confocal microscopy, oxidative stress, ion and membranepotential sensitive fluorescent probes, glioma cells |
| Description | In this work the dose dependent disorders of ion transport processes and mitochondrial membrane potential caused by hydrogen peroxide were investigated with fluorescencespectroscopic methods in C6-Glioma-Cells. These cells served as a model system for one glial subtype, the astrocytes. The transition pore is known to precede the programmed cell death, apoptosis. The apoptotic pathway is interrupted if all mitochondria of the affected cell undergo depolarisation. The following deficiency of high energy substrates leads to cell swelling and plasmamembrane disrupture, the so called onkosis. The results of this work indicate that the mitochondria are involved in the signal cascade of the oxidative stress response in C6-Glioma-Cells. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000052.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000527 |
| Title | Untersuchung der elektrischen Eigenschaften breitlueckiger Halbleiterschichtstrukturen für optoelektronische Anwendungen |
| Author or Creator | Fehrer, Michael |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | ZnSe, GaN, optoelectronic devices, laser diodes, magnetotransport |
| Description | For electrical characterization, experimental setups for current-voltage-, capacitance-voltage- and theHall-effect-technique were installed and used to get an insight into the electrical behaviourand degradation of the grown devices. Parallel to the optimization of the growth of deviceswithin other PhD theses, the main focus of this work was the investigation of metallizationschemes for laser and light emitting diodes. Two complete different technological proceduresto contact laser diodes grown on different substrate materials have been developed. Thus itis possible to distinguish between technology- and epitaxy-relevant problems and thereforeto optimize these topics separately. As a result, laser diodes on GaAs- and ZnSe-substrateshave been demonstrated operating in continuous-wave excitation from several seconds up tothree minutes, which is the best result ever obtained at an university. In the field of the III-Vmaterial GaN, the main topic was to investigate the basic electrical properties of molecularbeam epitaxial grown layers. Temperature dependent Hall effect measurements have beenperformed at a new Hall experiment setup to extract parameters for growth optimization. Twodifferent charge transport models for layers grown with two different plasma sources for thenitrogen supply were adopted successfully from other material systems and depositiontechniques. The advantage of molecular beam epitaxy for obtaining p-type conductivity withMagnesium without post-growth annealing could be shown. Also the search for alternativedopands for GaN was heavily investigated in connection with another PhD-work at thisinstitute. The contact technology for all used investigation techniques and for future lightemitting devices was established. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000054.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000540 |
| Title | Anwendung der Roentgenbeugung zur Analyse der strukturellen Eigenschaften von homo- und heteroepitaktischen Halbleiterschichten auf ZnSe-Basis |
| Author or Creator | Grossmann, Volker |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Hochaufloesende Roentgenbeugung, ZnSe, Homoepitaxie, Heteroepitaxie, Variable Messtemperatur, Thermische Verspannung |
| Description | An asymmetric relaxation was observed for the azimuth directions [110] and [1-10]. The dislocation density before and after heating was estimated from the diffuse scattering. Values of 3.3 *10^3 /cm and 13 *10^3 /cm were derived for the [110]-azimuth direction. The residual strain of single ZnSe layers on GaAs substrates due to work hardening was found to be 2.0 *10^(-4) in agreement with theoretical predictions. A critical layer thickness for work hardening of about 2.0 µm was derived. Comparing the thermal expansion of homo- and heteroepitaxially grown device relevant MgZnSSe layers showed nearly equal thermal expansion coefficients of both layer types. These measurements could be utilized to extrapolate the thermal expansion coefficient of MgSe in the zincblende structure. A value of 4.2 * 10^(-6) /K was derived for the temperature range from 300 K to 500 K. In the second part of the work, the influence of two different growth start procedures on the structural perfection of homoepitaxially grown ZnSe-based layers is discussed. A drastic increase in crystalline quality of the epitaxial layers resulted from various changes in growth procedure. The most important was the introduction of an {\em in situ} hydrogen plasma cleaning of the ZnSe substrates prior to the ZnSe growth. It provides a substrate surface free from contamination enabling to reduce the defect densities in the epitaxial layers by two orders of magnitude. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000055.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000558 |
| Title | Quantifizierung von Strukturen, Kinetik und Dynamik nekrobiologischer Prozesse mit Hilfe bildverarbeitender konfokaler Fluoreszenzmikroskopie |
| Author or Creator | Härtel, Steffen |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | el-4 ipc-81 hce image processing confocal microscopy fluorescent membrane dyes chromatin condensation DiI Laurdan DPH Syto13 segmentation scaling indices SIM |
| Description | Translocation of phosphatidylserine (PS) from the inner to the outer plasma membrane leaflet is presently discussed as a hallmark of apoptosis. The signalling which initialises the process and the translocation mechanism itself are still under investigation. Diffusion or enzymatic transport is suspected. Staurosporine induced PS-translocation was monitored in HCE-cells and in mouse lymphocytes (EL-4) by Annexin V-FITC (AV) fluorescence. QFM could not only reveal the percentage of AV positive and AV negative cells in both cultures, it could also derive that once initiated, PS-translocation in single HCE-cells is completed within less than ½h. This and other observations support nondiffusive PS-translocation. For toxicological investigations, early apoptotic parameters are essential. QFM detected two very early staurosporine induced effects in HCE- and EL-4-cells. In HCE-cells, a morphologic form of Karyorrhexis was discovered as early as 10min after induction. This form of chromatin condensation is probably initiated by the mitochondrial apoptotic inducing factor (AIF), which was recently discovered. Activated caspase-3, which is also discussed to initialise PS-translocation and chromatin condensation could be excluded for both events in HCE-cells. In EL-4-cells, perturbation of cellular migration and the exclusion of small cellular vesicles were detected within minutes after staurosporine induction. The results presented in this and other scientific publications validate the OFM method as a promising tool for future investigations. The method should work on many cellular events, in which fluorescent or non fluorescent texture or morphological features must be connected with statistical information. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000056.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000561 |
| Title | Inversion globaler Ozonvertikalverteilungen aus Messungen des Satelliteninstruments GOME |
| Author or Creator | Hoogen, Ricarda |
| Language | ger |
| Date | 1998 |
| Subject and Keywords | remote sensing, ozone, ozone profiles, retrieval theory, radiative transfer, GOME, GOMETRAN, ERS-2 Fernerkundung, Ozon, Ozonprofile, Inversionstheorie, Strahlungstransport |
| Description | Die stratosphaerische Ozonschicht schuetzt die Biosphaere vor der schaedlichen kurzwelligen UV-Strahlung. Spaetestens seit der Entdeckung des antarktischen Ozonlochs gilt es als erwiesen, dass diese wichtige Schutzschicht durch den Menschen akut gefaehrdet ist. UmVeraenderungen der Ozonverteilung rechtzeitig zu erkennen und um die chemischen und dynamischen Prozesse zu erforschen, die die Ozonverteilung bestimmen, benoetigt man globale Messungen der Ozonvertikalverteilung mit hinreichender raeumlicher und zeitlicher Aufloesung. Hier leistet das Global Ozone Monitoring Experiment (GOME) einen wichtigen Beitrag. GOME ist ein Spektrometer, das 1995 an Bord des zweiten europaeischen Fernerkundungssatelliten ERS-2 ins All gebracht wurde. Es misst die direkte Sonnenstrahlung und die von der Erde rueckgestreute solare Strahlung in Nadir-Geometrie. Dabei wird der Spektralbereich 240-790nm mit einer spektralen Aufloesung von 0.1-0.3nm abgedeckt. Im Rahmen der vorliegenden Arbeit wurde der Algorithmus FURM fuer die Ableitung von Ozonprofilen aus GOME-Messungen entwickelt. FURM beruht auf der sogenannten Kozlov-Informationsmatrix-Methode. Dabei handelt es sich um ein verbessertes Optimal-Estimation-Verfahren, das im Rahmen von FURM erstmals fuer die Auswertung von Satellitenmessungen eingesetzt wird. Ein weiterer Schwerpunkt der Arbeit ist die umfangreiche Validation der GOME-Ozonprofile mit Ozonsonden-, Lidar-, Mikrowellen- und SAGE-II-Satellitenmessungen. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000057.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000576 |
| Title | Strukturelle Charakterisierung von Gruppe-III-Nitriden mit Hilfe der hochaufloesenden Roentgenbeugung |
| Author or Creator | Kirchner, Verena |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | X-ray diffraction, group-III nitrides, strain, defects |
| Description | The investigation of typical defects in GaN layers is based on both X-ray results and transmission electron microscopy investigations from H. Selke. The defect structure in GaN layers grown on GaN nucleation layers is dominated by edge type threading dislocations and inversion domains. Furthermore, possible ion induced damages during molecular beam epitaxy were investigated, where acivated nitrogen for the GaN growth is delivered by a plasma discharge. By applying a substrate bias, nitrogen ions can be attracted or rejected during growth. Remarkable ion induced damages were found in GaN layers grown with an electron cyclotron resonance plasma source at negativ bias. The damages are comparable to those induced by ion implantation though the energies are much lower. The correlation of different kinds of defects with electrical and optical properties of the layers are presented in the last section of the work. It was found that not only the threading edge type dislocations can influence the Hall mobility and the full width at half maximum of the (D^0,X) emission but also the screw dislocations and stacking faults if the density of edge dislocations is approximately constant. Layers grown by molecular beam epitaxy on a GaN nucleation layer show an unknown emission around 3.440 eV. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000058.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000585 |
| Title | Analyse hydrographischer Schnitte mit Satellitenaltimetrie |
| Author or Creator | Losch, Martin |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | oceanography, hydrography, sea-surface height, satellite altimetry, geoid, inverse methods, adjoint method |
| Description | Dedicated satellite missions that will lead to high precision, high resolution geoid models are planned and/or in preparation. In this study, a particular method is presented that allows the use of sea surface height data, that is consistent with its error covariance. A first test of the model in a scenario with a small data set demonstrates some of the model´s characteristics. One has to handle the mathematical under-determination of the model by introducing sufficient prior information about the state of the ocean. This independent information could be taken from a hydrographic atlas. Twin experiments with a data set taken from a general circulation model of the FLAME group reveal the importance of improved geoid models for estimating the flow field along a hydrographic section. When the sea surface height data is weighted according to the error estimates of the future geoid models GRACE and GOCE integrated transports of volume and temperature can be determined with an accuracy that is improved over the case with no sea surface height data by 55%. With the error estimates of the currently available geoid model EGM96 the reduction of the estimated errors does not exceed 18%. The inverse model estimates integrated volume transports through the WOCE hydrographic section SR3, one of the choke point sections of the Antarctic Circumpolar Current, of 145-166 Sv. These values agree with the ones found by other authors. The error estimates range from 13 Sv without to 11 Sv with sea surface height data. The sea surface height data is referenced to the EGM96 geoid model and weighted according to its error covariance. Sea surface height data and an estimate of the sea surface height by the model are found to deviate from each other by more than the error estimates. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000059.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000593 |
| Title | Langfristige Variabilität der thermohalinen Zirkulation in einem gekoppelten Ozean-, Meereis-, Atmosphaerenmodell |
| Author or Creator | Meissner, Katrin Juliane |
| Language | ger |
| Date | 1999 |
| Subject and Keywords | thermohaline circulation, variability, energy and moisture balance model, paleoceanography |
| Description | The heat and moisture transports by transient eddies in the EMBM are parameterized by diffusion. The coupled model reproduces many aspects of today´s oceanic circulation. The most interesting features of the coupled model are the sensitivity of the thermohaline circulation to changes in the configuration, the multidecadal variability in the ocean-sea ice system, and the behaviour of the thermohaline circulation during transitions between glacial and interglacial periods. A very strong thermohaline circulation develops in the coupled system that is not evident in the stand-alone ocean model. An interesting aspect of this behaviour is the existence of a maximum strength in the overturning. Beyond this maximum, evaporation in the subtropics cannot balance the northward salt-transport. As a result, the watermasses over the deep water production sites become fresher, leading to a collapse of the thermohaline circulation. The associated changes in the sea ice cover prevent the system to recover. Acceleration and breakdown of the thermohaline circulation is expected during glaciation periods, when freshwater is stored on continents and the oceanic stratification in the North Atlantic is weakened by a reduced continental run-off and by enhanced cooling of surface water. Under these conditions a stronger thermohaline circulation compared to the reference case was established. Salinity was redistributed such that the deep water became more saline than today. During the following equilibrium conditions without net fresh water storage on the continents, the coupled model reproduces the shallow and weak overturning cell and many other aspects of the glacial circulation. All experiments are characterised by a highly variable thermohaline circulation on multidecadal timescales. This variability is maintained by the negative feedback between the strength of the overturning and sea ice cover. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000061.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000610 |
| Title | Untersuchung von Ceramid- und Adenosinanalogen bei der Apoptose von EL4-Zellen |
| Author or Creator | Popp, Katja |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Apoptosis, ceramide, tubercidin, plasma membrane, EL4-cells, NBD-C6, laurdan |
| Description | The lipids and the fatty acid composition are important regulators of cellular function and the membrane fluidity. The fluorescence dye laurdan was chosen to determine membrane fluidity in terms of generalised polarisation (GP) values in isolated membranes and whole cells. At the early apoptotic stages no significant alterations of the GP could be detected indicating a regulation mechanism to maintain membrane integrity. The investigation of apoptotic EL4 cell lipid compositions, ceramide metabolism, and modulation of the fatty acid spectra indicate that these variations stand for an early apoptotic phase, and that the mode of action of the lipid messenger ceramide is, compared to tubercidine, not a direct effect of the DNA fragmentation in the pathway of programmed cell death. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000062.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000623 |
| Title | Untersuchungen zum Ionentransport an der Zellinie EL-4 in Streßsituationen und während der Induktion von Apoptose |
| Author or Creator | Roboom, Arne |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | fluorescence, sodium, potassium, calcium, pH-value, apoptosis |
| Description | The increased release of protons by biochemical processes, by the Na( )/H( )-antiporter and by the H( )/lactate-symporter has an influence on the drop in the pH(int)-value. The increase of the Ca(int)(2 )-concentration takes place via Ca(2 )(ext)-ions. This increase probably is caused by the release of IP(3). The reduction of the Ca(2 )int)-concentration is achieved by the Na( )/Ca(2 )-antiporter. Ca(2 )-ion sensitive K( )-channels probably are involved in the leak of K( )-ions. Oxidative stress through H(2)O(2). The decrease of the Na( )-gradient across via the plasma membrane probably is responsible for the drop of the pH(int)-value. Another cause for this drop of pH(int)-value is the lack of ATP in the cell, wich has an influence on the H( )-ATPase and the Na( )/K( )-ATPase. The increase of the Ca(2 )(int)-concentration does not take place via the Na( )/Ca(2 )-antiporter. The depletion of intracellular Ca(2 )-stores probably opens Ca(2 )-channels in the plasma membrane which are dependent on Ca(2 )-ions. Induction of apoptosis through staurosporine. Na( )/H( )-antiporters, which are dependent on PKC are straightly affected by staurosporine. The lost of their efficiency is a cause for the drop of pH(int)-value. K( )/Cl(-)-cotransporters which are dependent on serine/threonine kinases, probably causes a decrease of the K( )(int)-concentration. The Na( )/Ca(2 )-antiporters are not involved in the increase of the Ca(2 )(int)-concentration. There was no release from intracellular stores. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000063.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000635 |
| Title | Wechselwirkungen zwischen Eis und Ozean im Weddellmeer: Studien mit einem gekoppelten Eis-Ozean-Modell des Südpolarmeeres |
| Author or Creator | Timmermann, Ralph |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | sea ice-ocean interaction, ice shelf-ocean interaction, Antarctic Circumpolar Wave, interannual variability, Maud Rise, deep convection, Weddell Gyre structure |
| Description | Quantitatively, a good agreement with observations is achieved. Investigations of sea ice-ocean interaction on the continental shelf in the southwestern Weddell Sea feature a strong correlation between fluctuations of atmospheric forcing and the variability of sea ice formation. Anomalies of meridional wind stress in the inner Weddell Sea are consistent with the phase of the Antarctic Circumpolar Wave (ACW). Positive anomalies of northward wind stress cause an increase of sea ice export in the same and of sea ice formation in the following year leading to an increased production of High Salinity Shelf Water. Driven by a varying density distribution over the continental shelf, the circulation in the Filchner-Ronne ice shelf cavity fluctuates between two modes, each of which features a characteristic distribution of basal freezing and melting regions. Thus, signals of interannual atmospheric variability propagate into the deep ocean and the sub-ice shelf cavities. The simulated Weddell Gyre features a pronounced double cell structure which is caused by the topographic effects of Maud Rise and Astrid Ridge. Flow around and across these elevations causes anomalies of vertical heat flux which affect the sea ice distribution only locally. The spring polynya in the region of Maud Rise appears as a wind-induced phenomenon which is not affected by regional topography. Deep convection in this region may be caused by modifications of the surface fresh water balance and does not depend on the existence of Maud Rise. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000064.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000640 |
| Title | Zwangskräfte bei einem Mehrkörpersystem mit drei Freiheitsgraden |
| Author or Creator | Tischenko, Oleg |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | forces of constraints, Waveletstransformation, Intermittence, Poincaré-maps, manybodysystem |
| Description | A mechanical system with three degrees of freedom in a gravitational field is analyzed for chaotic versus regular behavior, and for moments of constraint that act on its axes. The system consists of three connected rigid bodies each of which rotating about one axes. The vertical axis of the first body is fixed to the immobile base; the second body rotates about a horizontal axis which moves with the first, and the third body rotates about an axis in the second. Its moments of inertia A, B, C are assumed to obey C=A B. The motion is regular if the body is symmetric, A=B, otherwise the asymmetry parameter µ=(B-A)/B determines the degree of chaoticity. The different types of motion were identified with the help of Poincaré sections while the study of forces of constraints as functions of time was carried out using methods of time-frequency analysis: Fourier analysis in the case of regular, and wavelet analysis in the case of chaotic motion. It was noticed that for large values of µ the motion of the system shows an effect that can be described as intermittency, that is, there exist of long phases of motion during which the system behaves regularly. The reason for the occurence of such an effect is explained. It is observed that the forces of constraints obtain their maximal values in connection with the transition from one regular phase to another. In spite of the presence of chaos in the Poincaré-sections, for large intervals of µ, the wavelet transformation diagrams reflect a relatively regular behavior of the forces of constraints. Using classical statistical methods it would be possible, on the basis of analysis, to evaluate the long-term effects of chaotic motion on the wearing of materials in the bearings of the system. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000066.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000668 |
| Title | Der Transport von Wärme, Wasser und Salz in den Arktischen Ozean |
| Author or Creator | Cisewski, Boris |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Greenland Sea, Fram Strait, circulation, hydrography, watermasses, transports |
| Description | The combination of high resolution hydrographic and velocity measurements at identical grid points allows to avoid interpolation problems involved in the evaluation of mooring measurements. The mean circulation of the Greenland Sea is dominated by a large cyclonic and predominantly barotropic gyre. The calculated absolute velocities across the 75°N standard section question the existence of Koltermann´s (1991) postulated deep anticyclonic gyre. At 75°N the East Greenland Current (EGC) is identified over a distance of 140 km as a narrow jet which carries ice and polar water to the South. The total volume transport calculated for the region of the EGC is comparable with results of moored current meters and ranges between 12 and 29 Sv (Fahrbach et al., 1995 and Woodgate et al., 1999). In contrast to the EGC the Westspitsbergen Current (WSC) carries Atlantic Water (AW) to the North and exhibits a much larger mesoscale variability. The velocity field in the WSC is characterized by variable meanders and mesoscale eddies with typical horizontal dimensions of 50 km, whereas jet-like structures dominate in the EGC. Since the AW provides the major contributions to the meridional heat transport five realizations of the 75°N standard section were used to investigate its interannual variability. During the summers 1990 - 1998 the AW transports ranged between 2 and 7 Sv. The total heat transport across 75°N is estimated as 52 TW in September 1997 and 42 TW in September 1998. The total salt transport ranges between 5.2 and 5.6 e6 kg/s. Finally based upon five hydrographic sections taken between 70°N - 82°N and 25°W - 25°E during August/September 1997 a circulation and transport scheme for the principle water masses is constructed and compared to the results of Mauritzen´s inverse box model (Mauritzen, 1994). Both transport schemes are in good agreement. Between 75°N and 79°40´N the mean temperature of the AW decreases by 0.8°C while its density increases. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000067.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000672 |
| Title | Dezentralisierung des Gesundheitssystems in Brasilien: Grenzen und Möglichkeiten einer Strategie des Empowerments. |
| Author or Creator | Kleba, Maria Elisabeth |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Health Care, empowerment, Brazil |
| Description | The present work defends the participation of society in the construction of the health care service as a process of empowerment, and, consequently, as a factor of strengthening the individual and collective health. The empirical study has as its focus the participation of the Health Pastoral ( an organization of the Brazilian Catholic Church that offers assistance and advice to the communities) in the process of construction of the health care service in the West of Santa Catarina., situated in the south of Brazil. Active observation in encounters and courses, semi-structured interviews and reading of documents, were used as instruments of data collection, as well as others. The obtained data were interpreted through the analysis of content, and the principles of SUS were elected as uniting categories: universality, integration, decentralization and social participation. In this sense, limits and possibilities of the social participation in the sphere of the political-administrative decisions of the towns of the region coherent with such principles, were identified. The results indicate that the construction of the health care service in Brazil: 1) opens spaces and invites the citizens to be co-responsible for the social construction of health; 2) makes conflicts of interest emerge, demanding and promoting the availability of different groups to overcome selfish interests and to make decisions in favor of the collective; 3) broadens the understanding of the limits and possibilities in conformity with a system that promotes health. The transformations in which the involved actors experience, personal and collectively, reveal a process of empowerment, whose limits impose and redo themselves daily in the power game exercised in the relations and social institutions; and whose possibilities initiate in the indignation and will to change the order of things and become stronger in the recognizance. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000068.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000681 |
| Title | Soziokulturelle Wandlungsprozesse als Herausforderung an das Gesundheitswesen |
| Author or Creator | Müller, Dirk |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Health System Research. Federation, Corporatism and Social Security inGerman Health System. Social Policy. |
| Description | The present dissertation, connecting bases- and problem topics, analysesand discusses fundaments, motives and perspectives of development ingerman health system. Federation (´Bund´), counties and municipalauthorities pursue selective interests as well as corporatively unitedsuppliers do. Objectives of social securities and industry are opposingdiametrally. Hence, not known, specific singular symptoms, but techniquesand mechanisms for selfish handling-off federation and corporatism areevident, systematic challenges even to the health system. Social-economical bases of health policy are indeed directed from out of its´ realscope, and global changes of 1989 were ruling for increased significance ofpublic debate. Since then, a mainly subjective pression of competition isaccelerating, reinforcing economical divergence between incomes,expenses and tasks of social- and health policy. Employment andproductivity, demography, poverty, development of values and migration - inthose essentials for health policy, there is no release in sight. Even more,those structural problem dimensions are reinforcing mutually. Especiallyregarding epidemiological practice, health system is not competent to holdup, reduce or even to overcome harms with chronical potentials. Increasingscope of mortality, biographical extension of harmed life phases andadvance of such restrictions into more younger cohorts, are evident´epidemiological illusions´. Nevertheless, supply with empirical dataremains permanently unaltered. Given that, german federation has nointerest in a real, sustainable reform of known, structural and practicalproblem subjects. Epidemiological and economical tasks in its´comprehension, these issues are indeed market in a ´trade of future´ for anunleashed private economy. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000069.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000692 |
| Title | Aspekte der Glücksspielsucht: Selbstkonzept, Affektregulation und Achse-I-Komorbidität |
| Author or Creator | Rahman, Susanne |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Pathological Gambling - Self-Concept - Comorbidity - Affect-Regulation- Psychological Dependency |
| Description | 28 male pathological gamblers were compared to 28 controls concerning self-concept, emotionality (anger, anxiety, depression), affect regulation (alexithymia, fear/ avoidance of emotions) and achsis-I-comorbidity. Significant differences between groups concerning all variables could be found. Furthermore highly significant correlations between negative self-concept, negative affect as well as avoidance of emotions were investigated within the group of patholodical gamblers.Data served to develop a vicious-circle-model of pathological gambling. Taken into consideration atiological models of addiction as well as latest results concerning substance-related addictions the results of the present study confirm the assumption that pathological gambling is an substance-independent addiction disorder or a pychological dependency.Implications for therapy are discussed. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000070.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000700 |
| Title | Proteinstruktur und Proteinfaltungsanalysen mit Hilfe der Ramanspektroskopie: Untersuchungen an Modellpeptiden zur Optimierung der Methodik |
| Author or Creator | Mix, Guido |
| Language | ger |
| Date | 2000 |
| Subject and Keywords | Raman spectroscopy, model peptides, protein structure, protein folding, amide bands, protein structure marker |
| Description | In this study we investigated small model peptides by visible and UV resonance Raman spectroscopy to obtain a more detailed understanding about the normal modes giving rise to the protein secondary structure marker bands in Raman and infrared spectra. They predominantly arise from vibrations of the peptide groups. Additionally, the spectra of b-sheet and ´random coil´ structures display a resonance enhanced band at about 1400cm-1 which is generally assigned to the CaH bending (b) vibration. By analyzing the structure marker bands in the UV-resonance Raman spectrum it is possible to directly determine protein secondary structures in solution. Furthermore, the utility of UV resonance Raman spectroscopy to probe the earliest events of thermal unfolding of an a-helical peptide was demonstrated. In this present study we investigated di- and tripeptides, containing one and two amide linkages respectively, to obtain a deeper insight into the origin of the structure sensitive bands. The results of these investigations allow us to characterize the enhancement pattern of the CaH band in a protein or polypeptide. We show that only the N-terminal CaHb and not the C-terminal CaHb band of a peptide group is revealed in the UV-Raman spectrum. For longer peptides we found that the intensity of the CaHb depends linearly on the number of amino acid residues minus the C-terminal residue. Hence, this band can be used as a direct measure of the length of secondary structure motifs within a more complex protein structure. With respect to AIII, we provide compelling evidence that this vibration is localized in various tripeptides which sample a significant portion of the Ramachandran plot. Furthermore, we show that the AIII eigenvector contains internal coordinates of the CaHb group and that this contribution mainly determines the AIII frequency position in UV-Raman spectra of investigated molecules. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000071.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000715 |
| Title | Interfacial issues in wide-bandgap II-VI materials and related multiple quantum well structures |
| Author or Creator | Pelucchi, Emauele |
| Language | eng |
| Date | 2001 |
| Subject and Keywords | MBE, II-VI, Schottky barriers, multiple quantum wells, lattice matching, ZnMgSe |
| Description | This thesis is devoted to exploring two main processes potentially relevant to the physics and technology of wide-bandgap II-VI materials: :br:i) fabrication of Zn1-yCdySe quantum wells on lattice-matched substrates to implement strain-free blue-green emitters; :br:ii) optimization of the properties of metal/II-VI contacts through modification of the local interface environment. In the first area, we showed that graded composition InxGa1-xAs buffer layers on GaAs (001) wafers can be used to match the Zn1-yCdySe quantum well lattice parameter. Detailed studies of the electronic and structural properties of Zn1-zMgzSe alloys and Zn1 yCdySe/Zn1-zMgzSe heterojunction interfaces allowed us to design and fabricate strain-free Zn1 yCdySe/Zn1-zMgzSe multiple quantum well structures on the novel InxGa1-xAs substrates. We found that the surface corrugations of the III-V buffer do not hinder the structural quality of the quantum wells, and give only rise to long-period coherent undulations of quantum well and barrier layers. In the area of metal/II-VI semiconductor junctions, our experimental studies of Zn/ZnSe (001) interfaces stimulated new theoretical calculations of interface formation energies and electronic structure. Both experiment and theory indicate that this interface represents a unique example of ideally unreactive metal/ZnSe contact. Conversely, we found that Au/ZnSe contacts show evidence of interface reactions, in contrast with most earlier reports. Significant lateral inhomogeneities in the interface parameters are likely related to preferential reaction at steps and kinks of the ZnSe(001) surface. By inserting ultrathin layers of Zn at the interface between Au and ZnSe(001), we demonstrated the possibility of inducing large modifications in the Schottky barrier height, together with an improved lateral homogeneity and ideality of the resulting metal/ZnSe contacts. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000073.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000000737 |
| Title | A new algorithm to retrieve the sea ice concentration using weather-corrected 85GHz SSM/I measurements |
| Author or Creator | Kern, Stefan |
| Language | eng |
| Date | 2001 |
| Subject and Keywords | Microwave Remote Sensing - Polar Meteorology - Sea Ice - Radiative Transfer |
| Description | Sea ice is a very important component of the climate system. While the Arctic sea ice extent has retreated during the past 20 years, it has remained constant in the Antarctic. In order to better understand the role of sea ice in the climate system in the context of global warming currently used coupled Atmosphere-Ocean Global Circulation Models have to be improved. This requires to know the sea ice concentration C for a long period for both hemispheres and at the best possible spatial resolution. Currently used methods to obtain C like the NASA Team (NT) algorithm are based on data acquired by the Special Sensor Microwave/Imager (SSM/I) at 19 and 37GHz. The SEA LION (SL) algorithm presented here allows to infer C from the polarization P at 85GHz taking advantage of the higher spatial resolution at this frequency. However, the decrease of P caused by the weather influence leads to an overestimation of C. Therefore, P is corrected using a radiative transfer model and atmospheric data taken from Numerical Weather Prediction models and/or derived from SSM/I measurements. The various sea ice and snow properties are considered calculating monthly sea ice tie points. The average standard deviation of C derived with the SL algorithm is 12% for C < 50% and below 5% for C > 90%. The SL ice edge agrees within 10km with the one evident in VIS/IR images. The SL ice concentration gradient across the marginal ice zone (MIZ) agrees much better with the one evident in SAR images compared to results of the NT algorithm. Using the higher spatial resolution at 85GHz the SL algorithm allows to detect smaller open water areas than known algorithms. A major limitation of the SL algorithm arises from the quality of atmospheric data needed for the weather correction. A spatial resolution of these data lower than the 85GHz SSM/I channels and/or a time lag larger than half an hour between both data sets can cause relative errors above 100%, particulary in the cloud-covered parts of the MIZ. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000100.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001005 |
| Title | Allokative und distributive Effekte regulierten Wettbewerbs in sozialen Krankenversicherungssystemen Wirtschaftstheoretische Fundierung, tatsächliche Auswirkungen und Implementationsprobleme am Beispiel der Niederlande |
| Author or Creator | Greß, Stefan |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Health Insurance; Germany, Netherland; Competition; Competition Theory |
| Description | The concept of managed competition in health care attracts a lot of attention from policy makers not only in Germany but from countries all around the world. The aim of this concept is to increase the efficiency of health care systems as well as maintaining solidarity. Since the health care system of the Netherlands is institutionally and culturally quite similar to the German system it is promising to test the behavioral assumptions of the model and to draw conclusions for Germany. Furthermore this work tries to analyze several economic theories of competition with regard to the functions and aims of competition.The results of the research show that the spirit of competition in the Dutch health care system is quite underdeveloped. Consumers do switch sickness funds, although to a much lesser extent than expectet. Instead of competing with each other, insurers try to retain regional monopolies. There is no selective contracting between insurers and providers of care. Effects on solidarity also are very limited, although the exclusion of dental services from the basic insurance packet seems to have negative effects on the access to health care for lower income groups. The reasons for the low degree of intensity of competition are twofold. First, there are serious theoretical deficiencies of the managed competition model. Second, the incentives and instruments for competition in the Dutch system diverge to a significant degree from the ideal model of managed competion while market actors at the same time do not find it rewarding to use the incentives and instrument they have access to. Consequently, policy makers have to face considerable challenges if they try to implement managed competition model in Germany. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000115.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001154 |
| Title | Integration von galvanisch realisierten Sensorstrukturen auf mikroelektronischen CMOS-Schaltungen |
| Author or Creator | Wycisk, Michael Christian |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | inertial sensor, MEMS, electroplating, switch, electrical contact |
| Description | This dissertation describes the development of a sensor for measuring acceleration-thresholds in the low-g-range. The unusual characteristic of this sensor consists of the feature to fabricate the sensor on top of a CMOS signal processing circuit. In this context, the additive electroplating technology combines the advantages of monolithic- and hybrid-integrated sensors with respect to the reduction of interconnections, short development cycles, low tooling costs, and high design flexibility. A detailed technical concept for the fabrication of electroplated micromechanical acceleration switches is presented in this work. It comprises the aspects of the interface technology between the ASIC and the sensor structure, the sensor fabrication and the back-end processing to capsulate the dies. The microswitches are fabricated using microforms, which are moulded by an electroplating process, thus resulting in laterally moveable metallic microstructures. Therefore a low temperature ! dry process was developed to remove the sacrificial resist layer in order to eliminate the dangers of stiction. Other technological improvements were done to increase the yield of the processflow. Therefore optimised technologies considering the electroplating process and the coating of the electrical contacts have been developed. The developed packaging technology enables the hermetic sealing of these micromechanical structures and provides a mechanical overload protection. The additive electroplating technology offers an new fabrication method for a variety of further devices such as coils, interdigitated electrodes, springs and others structures which can be used in various different applications. The switch devices fabricated with this technology were tested extensively and showed very good performance characteristics. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000127.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001274 |
| Title | Bildungsurlaub für Arbeitnehmer. Ein Weg zur Verwirklichung des Grundrechts auf Bildung? |
| Author or Creator | Däubler- Gmelin, Herta |
| Language | ger |
| Date | 1975 |
| Description | |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000136.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001364 |
| Title | Entwicklung und Anwendung eines photochemischen schräge Säulen Modell-Paketes zur Interpretation von DOAS-Daten atmosphärischer Spurengase |
| Author or Creator | Müller, Richard |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Ozon,arktischer Ozonabbau, Stratosphäre, Cemie, DOAS, schräge Säulen, Modell, Atmosphäre, ozone, stratospheric chemistry, DOAS, slant path, atmospheric model |
| Description | Besides measurements of atmospheric trace gases and laboratory studies of chemical reactions, modelling has been recognised to be of increasing importance to improve our knowledge of the atmosphere and the capabilities of photochemical models. Main scope of this work was the development of a photochemical atmospheric model, which was especielly designed for the interpretation of Differential Optical Absorption measurments (DOAS). This model has been used to improve our knowledge of atmospheric chemistry. For example, for the first time it was possible to demonstrate that a significant amount of IO in a range of 0.65 to 0.8 pptv is present in the stratosphere in the polar region (Ny-Alesund,Spitzbergen). Moreover it has been shown that such amounts of stratospheric IO lead to an additional Ozone loss in the range of 10 % in cold arctic winters. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000139.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001393 |
| Title | Untersuchung der Photooxidantien Wasserstoffperoxid, Methylhydroperoxid und Formaldehyd in der Troposphäre der Antarktis |
| Author or Creator | Riedel, Katja |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Modell, Schnee, Atmosphäre, Hydroperoxide; atmospheric chemistry, photochemistry, antarctic troposphere, hydroperoxides, ozone depletion, seasonal variation, snow, remote, model calculations |
| Description | Photooxidants play an important role for the oxidation capacity of the troposphere. The presented work deals with seasonal changes of atmospheric photooxidants like hydrogen peroxide (H2O2), methylhydroperoxide (MHP) and formaldehyde (HCHO). The principal purpose was to follow and quantify the mixing-ratios of these photochemical species for the first time over a complete annual cycle in Antarctica. During two field campaigns at the German Antarctic station Neumayer (overwintering campaign from January 1997 until March 1998 and a shorter campaign from January to March 1999) continuous measurements of atmospheric mixing-ratios were performed. A continuous wet-chemical technique was used for peroxides and formaldehyde sampling and analysis. Species were quantified by fluorescence detection. In order to compare the results and measurements with well-known reaction mechanisms a photochemical box model was applied. The obtained time series show a pronounced seasonal variation with higher values during summer. For the first time atmospheric concentrations of H2O2, MHP and HCHO were documented during polar night in winter. The mixing-ratios were significantly higher than expected due to missing actinic radiation essential for photochemical production. Trajectory analyses and calculations with a three-dimensional model showed that during winter the mixing-ratios of photooxidants are mainly affected by long-range transport in the free troposphere. Investigations during the Antarctic ´´ozone hole period´´ show no significant impact of the increased UV-B radiation on the photooxidants. The findings of this work contribute to a better understanding of the photochemistry of the investigated trace gases in the clean troposphere of Antarctica and provide a useful data record for further photochemical modeling. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000144.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001440 |
| Title | Biogeochemistry of Dissolved Carbohydrates in the Arctic |
| Author or Creator | Engbrodt, Ralph |
| Language | eng |
| Date | 2001 |
| Subject and Keywords | carbohydrates, XAD, fractionation, humic substances, neutral sugars, Arctic Ocean, Russian Rivers |
| Description | A detailed characterization of dissolved carbohydrates in the Siberian rivers and shelf areas, the Kara and Laptev Seas, the central Arctic Ocean, Fram Strait, and Greenland Sea is presented. Highest concentrations of total carbohydrates (25 mM C on average) were measured in the samples of the Russian rivers. A strong decrease of the concentrations occurred during the transition into the marine environment (5.3 mM C on average). In deep waters, the total carbohydrate concentrations were below 2 mM C. The main component of dissolved carbohydrates was glucose, which was well suited for the characterization of the diagenetic state of DOM. Terrigenous and diagenetic old marine DOM had very low glucose proportions between 20 and 28% of total carbohydrates. In contrast, freshly produced DOM was characterized by high glucose proportions of up to 86%. Indicators for diagenetic modifications were also fucose, rhamnose, and arabinose, whose proportions increased with increasing diagenetic degree to approx. 40%. The composition of refractory carbohydrates was determined by extraction of recalcitrant organic matter from the seawater using a combination of XAD-2 and -4 adsorption resins. With increasing age of DOM, the proportion of the humic substances of the total DOC and of the total carbohydrates increased from 45% in surface samples to 67% in the deep sea. Part of refractory carbohydrates may be composed of chemically modified carbohydrates, which are not accessible with the chromatographic method. More than the half of the XAD-extractable sugars of surface samples and more than 70% of deep sea samples were found in the unpolar fraction. It was concluded that the majority of refractory carbohydrates were bound or associated to unpolar compounds of small molecular size. Using the ratio of the sum of the molar proportions of the deoxysugars and the sum of arabinose and xylose, the extracted humic substances were characterized with respect to their diagenetic degree. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000154.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001540 |
| Title | Die Bedeutung ektotropher Mykorrhiza fuer die Naehrstoffversorgung von Nothofagus obliqua. Untersuchungen unter Beruecksichtigung der Boden- und Naehrstoffbedingungen der Nothofagus-Waelder in Suedchile im Hinblick auf Wiederaufforstung und nachhaltige Forstwirtschaft |
| Author or Creator | Alvarez, Maricel |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Nothofagus, Ektomykorrhiza, Phosphataseaktivität, Laser Scanning Mikroskopie, ELF-97, Naehrstoffversorgung |
| Description | Nothofagus species form the most important native constituents in the temperate humid forests of southern Chile. The presented work concentrates on the evaluation of the relevance of several specific and non-specific ectomycorrhiza for Nothofagus. First, a general survey of ectomycorrhiza found in association to N. obliqua and P. radiata near Valdivia (Chile) is presented. Further work concentrated on the mycorrhizal fungi Austropaxillus boletinoides, Boletus loyo, Austropaxillus statuum, Cenococcum geophilum, Paxillus involutus, Pisolithus tinctorius, and Descolea antartica. The extra-cellular and membrane bound phosphatase activity was determined in cultured mycelium, roots and entire mycorrhiza under different external parameters and growth conditions. Phosphatase activities of mycorrhiza-associations are of increased interest in areas of limited P supply. Extra-cellular and membrane bound phosphatase activity (PA) were quantified at different pH-values (3-7) in isolated cultures of A. boletinoides, P. involutus, P. tinctorius, D. antartica, and C. geophilum, which had been adapted to grow in media with varying concentrations of dissolved P. For the detection of membrane bound PA in fungal hyphae, we compared the pNPP-method with a newly developed method based on enzyme activated fluorescence of ELF-97 substrate and image processed confocal Laser-Scanning-Microscopy. For membrane bound PA, the fluorescence based method not only reproduced qualitatively the results obtained by pNPP, but additionally contributed valuable information about the structure and distribution of the phosphatase spots in the fungi. The ELF-97 method also provided reliable properties to be used for the determination of PA even in mycorrhizal and non-mycorrhizal roots of N. obliqua. In conclusion the observations underline that positive effects of mycorrhiza associations for the plant highly depend on the specific partners, the specific nutrient, and the specific external conditions (pH). |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000158.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001581 |
| Title | North Atlantic Deep Water and Antarctic Bottom Water: Their Interaction and Influence on Modes of the Global Ocean Circulation |
| Author or Creator | Brix, Holger |
| Language | eng |
| Date | 2001 |
| Subject and Keywords | Interhemisphärische Wechselwirkungen,thermohaline Zirkulation,Ozeanmodellierung |
| Description | Interhemispheric signal transmission in the Atlantic Ocean connects the deep water production regions of both hemispheres. The nature of these interactions and large scale responses to perturbations on time scales of years to millenia have been investigated using a global general circulation model based on the primitive equations coupled to a dynamic-thermodynamic sea ice model with a viscous-plastic rheology. The coupled model reproduces many aspects of today´s oceanic circulation. Testing the model´s sensitivity revealed a strong dependence of the model results from eddy diffusivities, filtering and topographic effects.:p:The internal variability in the ocean-sea ice system has been addressed by analyzing the model results with statistical techniques. A decadal oscillation could be identified in the Southern Ocean. A sequence of Kelvin and Rossby waves carries anomalies in this frequency band northward across the equator.:p:Longer-term variability in the ocean is mainly determined by advective processes. A set of experiments in which the surface boundary conditions were changed showed the necessity to continue integrations over thousands of years until new equilibria are established. Buoyancy changes in the Weddell and Labrador Seas exert a direct effect on the overturning cells of the respective hemisphere. They influence the density structure of the deep ocean and thereby lead to alterations in the strength of the ACC. The model results suggest an influence of the ACC on convective activities in the Southern Ocean. Changing the wind stress south of 30S influences the magnitude of the deep water production of both hemispheres. The interhemispheric effect in these experiments cannot be explained solely by advective mechanisms (contradicting previous studies). Switching off the wind stress over the latitude band of the Drake Passage leads to a slow gradual decrease of the water mass transport in the ACC resulting in an almost complete cessation. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000164.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001649 |
| Title | Kennwerte psychologischer Testverfahren |
| Author or Creator | Müller, Jörg Michael |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | error of measurement, usability, test selection, diagnostic, reliability, testscore distribution, quality control, IRT |
| Description | The work "Kennwerte psychologischer Testverfahren" contains an introduction and three articles. The introduction clarifies the meaning and use of coefficients to evaluate the quality of a test, such as reliability or validity. The introduction closes with five new coefficients to describe different aspects of a test: "Ausdehnung", "Ausschöpfung", "Differenziertheit", "Mess-Effizienz" and "Personenunterscheidungsvermögen". The first article concerns criteria of usability, which help to distinguish a poorly understandable coefficient from a good one. The coefficient "Differenziertheit" is based on the critical difference of test scores and shows how many of these differences fit on the whole scale. The second article proposes the term "Personenunterscheidungsvermögen" (PUV). This index allows one to estimate the expectation (probability) of (statistically) different scores. One advantage of this coefficient is that it is independent of the test theoretical foundation of psychometric assessment, which makes it possible to use the same coefficient for categorical and metric constructs. This index as well fulfils most of the criteria of usability. The last article presumes differences in the variability of a psychological dimension and shows how to display these differences. For this purpose, a new kind of standardization based on the differences of probabilities is shown which can be derived from the application of a Rasch scale. This application, to measure the spreedness (Ausdehnung) of a psychological dimension, leads to a new interpretation of a Rasch scale. This article is in press in the journal "Zeitschrift für Differentielle und Persönlichkeitspsychologie". This new coefficient offers many new possibilities, such as testing construct validity or choosing those dimensions for prediction that show bigger differences between persons. More information under http://www.joergmmueller.de/default.htm |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000165.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001654 |
| Title | Mikrosystemtechnische Sensoren in relativ bewegten Systemen für die industrielle Anwendung |
| Author or Creator | Ahrens, Oliver |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Oberflächenmikromechanik, Ultraschallwandler, elektrostatische Anregung, Herstellungsprozeß, Abstandsmessung |
| Description | The present thesis addresses two major fields. First, the dynamic measurement of displacement with a resolution of micrometers is considered. Second, the development of a new class of capacitive micromachined ultrasonic transducers (cMUT) is performed. Within the first scope, an exemplary field of application, i.e. the gripper of a robotic handling system, has been chosen. The commonly employed sensor principles for these purposes are reviewed. In addition, a number of three sensor principles has been selected for an experimental investigation. These distance sensors work within a measuring range of 200 µm up to 3 mm and a resolution of a few micrometers was targeted. Their usability has been specified in terms of repeating accuracy ("Wiederholpräzision").Going on from this preselection of sensor principles, the ultrasonic transducer has been chosen for further development. The state-of-the-art of ultrasonic transducers for air-borne ultrasound is outlined. The given drawbacks of the prevailing thickness mode resonators motivate the development of different transducer principles. One alternative is given by membrane resonators. Here, the ultrasound is generated by the electrostatic stimulation of the membrane, whereas the detection of ultrasound is performed by the measurement of changes in the capacitance of the transducer. Within this thesis it is shown that the microsystem technology offers advantageous possibilities to manufacture ultrasonic transducers with a number of new distinctive features. In particular, the technologies of surface micromachining were employed to develop a novel transducer set-up Since the fabrication of cMUT by means of microsystem technology emerged in 1994, two varying set-ups have been realized that differ from the present one. In contrast to those, the present set-up of a cMUT is particularly suitable for low voltage applications. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000168.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001686 |
| Title | Das west-östliche Lebensprinzip in Hermann Hesses Werk. Eine Antwort auf existenzielle Fragen. |
| Author or Creator | Bergold, Stephanie |
| Language | ger |
| Date | 2001 |
| Subject and Keywords | Polarität, Dualität, Bewusstsein, integtrales Bewusstsein, Jean Gebser, Ken Wilber, Taoismus, Buddhismus, Hermann Hesse, Literatur-Curriculum, DidaktikMiteinander, Antipädagogik, kreatives Schreiben |
| Description | Die Hauptthese der Arbeit ist: Wer die Verantwortung für sein Leben von sich schiebt, schiebt sein Leben von sich. Wir sind für alles verantwortlich, was wir tun, lassen und was uns widerfährt.In Hermann Hesses wie in Jean Gebsers Werk geht es im Kern um die gleiche Erkenntnis.Im ersten Teil der Arbeit werden die Vorstellungen von Bewusstsein, wie sie 'westlichem' und 'östlichem' Denken zugrunde liegen, geklärt. Anhand der Bewusstseinstheorie Jean Gebsers wird dargelegt, wie heute, mit der Herausbildung des integralen Bewusstseins, die Überwindung dieser Polarität möglich ist. Im zweiten Teil wird untersucht, inwieweit Hermann Hesse in seinem Werk diese Überwindung, die heute unsere Aufgabe ist, leistet.Im dritten Teil wird ein neues Literatur-Curriculum dargestellt, das auf Freiwilligkeit und der Übernahme der vollen Verantwortung für das eigene Leben basiert.\n\nThe main thesis of the work is that anyone who pushes away responsibility for his life pushes his life away. We are responsible for everything that we do, everything that we leave undone and everything that happens to us.In their essence the works of Hermann Hesse and Jean Gebser impart the same cognition.The first part clarifies the concepts of consciousness on which à ´westernà ´ and à ´easternà ´ thinking is based. It explains how Jean Gebserà ´s theory of consciousness allows for the possibility of overcoming this polarity today through the development of the integral consciousness, a challenge that remains a primary task for Man today.In the third part a new choice of background reading for school students (Literatur-Curriculum) is described which is based on voluntariness and undertaking responsibility for oneà ´s own life. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000170.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-00100049-13 |
| Title | Dada, Präexil und "Die Freie Zeitung" - Ernst Bloch, homo ludens und Tänzer; der rastlose Hugo Ball auf der Suche nach Heimat; und ihre Weggefährten und Gegner in der Schweiz 1916-1919. |
| Author or Creator | Korol, Martin |
| Language | ger |
| Date | 1997 |
| Subject and Keywords | Bloch, Ernst; Elsa Bloch-von Stritzki; Ball, Hugo, Hennings, Emmy Fried; Alfred Hermann; Präexil ;Exil ; Dadaismus; Haltung; Tanz, Gleichzeitigkeiten; Studentenbewegung |
| Description | Während des Ersten Weltkrieges weilten bürgerliche Oppositionelle aus Deutsch und Österreich-Ungarn in der Schweiz, warteten auf das Ende des Krieges, begründeten den Dadaismus und beteiligten sich an einem Propagandablatt der Entente. Es war ein Vorlauf zum Exil ab 1933. |
| Resource Identifier | http://elib.suub.uni-bremen.de/peid/D00000174.html |
| Source | http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000001749 |
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