• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 30
  • 19
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 62
  • 34
  • 33
  • 26
  • 22
  • 22
  • 21
  • 21
  • 19
  • 19
  • 19
  • 19
  • 13
  • 11
  • 10
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Excited-State Dynamics in Open-Shell Molecules / Dynamique des états excités dans des molécules à couche ouverte / Dynamik angeregter Zustände in offenschaligen Molekülen

Röder, Anja 10 July 2017 (has links)
Dans cette thèse, la dynamique des états excités des radicaux et biradicaux a été examinée en utilisant la spectroscopie pompe-sonde résolu en temps à l'échelle femto-seconde. Les molécules à couche ouverte jouent un rôle primordial comme intermédiaires dans les processus de combustions, dans la formation de la suie et des hydrocarbures aromatiques polycycliques, dans la chimie atmosphérique ou dans la formation des molécules organiques complexes dans le milieu interstellaire et dans les nuages galactiques. Dans tous ces processus les molécules sont souvent excitées, soit par échauffement thermique, soit par irridation. En conséquence la réactivité et la dynamique de ces états excités sont particulièrement intéressantes afin d'obtenir une compréhension globale de ces processus. Les radicaux et biradicaux ont été produits par pyrolyse à partir de molécules précurseur adaptées et ont été examinés dans un jet moléculaire dans des conditions sans collisions. Les radicaux ont ensuite été portés dans un état excité bien défini, et ionisés avec un deuxième laser. La spectrométrie de masse à temps de vol permet une première identification de la molécule qui est complété avec des spectres de photoélectrons, si le spectre de masse ne montre majoritairement qu'une seule masse. Les spectres de photoélectron ont été obtenus par l'imagerie de vitesse, permettant d'obtenir des informations sur l'état électronique au moment de l'ionisation des électrons. L'imagerie de vitesse des ions permets de distinguer des ions issu d'une ionisation directe et ceux issu d'une ionisation dissociative. Pendant cette thèse un algorithme modifié de pBasex a été développé et implémenté en python, un algorithme qui inverse des images sans interpolation des points expérimentaux. Pour des images bruitées cet algorithme montre une meilleure performance. / In this thesis the excited-state dynamics of radicals and biradicals were characterized with femto-second pump-probe spectroscopy. These open-shell molecules play important roles as combustion intermediates, in the formation of soot and polycyclic aromatic hydrocarbons, in atmospheric chemistry and in the formation of complex molecules in the interstellar medium and galactic clouds. In these processes molecules frequently occur in some excited state, excited either by thermal energy or radiation. Knowledge of the reactivity and dynamics of these excited states complete our understanding of these complex processes. These highly reactive molecules were produced via pyrolysis from suitable precursors and examined in a molecular beam under collision-free conditions. A first laser now excites the molecule, and a second laser ionizes it. Time-of-flight mass spectrometry allowed a first identification of the molecule, which was completed by the photoelectron spectrum. The photoelectron spectrum was obtained via velocity-map imaging, providing an insight in the electronic states involved. Ion velocity map imaging allowed separation of signal from direct ionization of the radical in the molecular beam and dissociative photoionization of the precursor. During this thesis a modified pBasex algorithm was developed and implemented in python, providing an image inversion tool without interpolation of data points. Especially for noisy photoelectron images this new algorithm delivers better results. / In der vorliegenden Dissertation wurde die Dynamik angeregter Zustände von Radikalen und Biradikalen mittels femtosekunden-zeitaufgelöster Anrege-Abfragespektroskopie untersucht. Radikale und Biradikale sind nicht nur wichtige Zwischenprodukte in Verbrennungsprozessen, sondern auch bei der Bildung von Ruß und polyzyklischen aromatischen Kohlenwasserstoffen beteiligt. Des Weiteren spielen sie eine wichtige Rolle in der Atmosphärenchemie und bei der Bildung komplexer Moleküle im interstellaren Medium. Von entscheidender Bedeutung ist in den genannten Prozessen die Anregung der Radikalen und Biradikale in energetisch höhere Zustände, dies geschieht entweder durch thermische Energie oder mittels Strahlung. Für das Verständnis der ablaufenden Vorgänge ist es zwingend erforderlich die Dynamik der angeregten zu verstehen. Die Radikale und Biradikale wurden dafür mittels Pyrolyse eines geeigneten Vorläufers erzeugt, und anschließend unter kollisionsfreien Bedingungen im Molekularstrahl spektroskopisch untersucht. Hierbei regt ein erster Laser das Molekül an, ein zweiter Laser ionisiert es. Mittels Flugzeitmassenspektrometrie wurden die Moleküle identifiziert, und mittels Photoelektronenspektroskopie weiter charackterisiert - unter der Bedingung, dass im Massenspektrum eine Masse dominiert. Das Photoelektronenspektrum wurde mittels Velocity-Map Imaging aufgenommen und gibt einen Einblick in den elektronischen Zustand im Augenblick der Ionisations. Die Velocity-Map Imaging-Technik von Ionen erlaubt außerdem die Unterscheidung von Ionen aus direkter Ionisation und dissoziativer Photoionisation. In diesem Rahmen wurde auch ein modifizierter pBasex-Algorithmus entwickelt und in Python implementiert. Dieser kommt im Gegensatz zum herkömmlichen pBasex-Algorithmus komplett ohne Interpolation der Datenpunkte aus. Besonders bei verrauschten Photoelektronenspektren liefert dieser Algorithmus bessere Ergebnisse.
22

In-Hospital Outcomes after Radical Cystectomy for Bladder Cancer: Comparing National Trends in the United States and Germany from 2006 to 2014

Groeben, Christer, Koch, Rainer, Baunacke, Martin, Borkowetz, Angelika, Wirth, Manfred P., Huber, Johannes 07 August 2020 (has links)
Background: Radical cystectomy (RC) still poses a significant risk for mortality and morbidity. Objectives: We compared in-hospital outcomes after RC in the United States and Germany using population-based data. Methods: We compared data from the US Nationwide Inpatient Sample to the German hospital billing database. Mortality and transfusion during hospital stay and length of stay (LOS) were evaluated. Results: In all, 17,711 (the United States) and 60,447 (Germany) cases were included. The share of robot-assisted RC increased to 20.5% in the United States vs. 2.3% in Germany (p < 0.001). In-hospital mortality was 1.9% (the United States) vs. 4.6% (Germany), transfusion rates were 34.2% (the United States) vs. 58.7% (Germany), and LOS was 10.7 (the United States) vs. 25.1 days (Germany; all p < 0.001). On multivariate analysis, higher patient age and lower annual hospital caseload were associated with increased mortality and longer LOS. Minimalinvasive surgery was associated with less blood transfusion and shorter LOS in the United States vs. hospital caseload and choice of urinary diversion in Germany. Conclusions: Healthcare systems might exert a relevant impact on outcomes of oncologic surgery. Increased in-hospital mortality rates in Germany seem to be partly explained by much longer LOS compared to those in the United States. Annual caseload seems to be influential on in-hospital outcomes raising the question of centralization of RC.
23

Impact of Myeloperoxidase-derived oxidants on the product profile of human 5-Lipoxygenase

Zschaler, Josefin, Dorow, Juliane, Schöpe, Louisa, Ceglarek, Uta, Arnhold, Jürgen January 2015 (has links)
Human 5-lipoxygenase (5-LOX) oxidizes arachidonic acid to 5S-hydroperoxy-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-HpETE) and leukotriene (LT) A4. In neutrophils, LTA4 is further converted to the potent chemoattractant LTB4. These cells also contain the heme enzyme myeloperoxidase (MPO), which produces several potent oxidants such as hypochlorous acid (HOCl), which are involved in pathogen defense and immune regulation. Here, we addressed the question whether MPO-derived oxidants are able to affect the activity of 5-LOX and the product profile of this enzyme. Human 5-LOX was incubated with increasing amounts of HOCl or HOBr. Afterward, arachidonic acid metabolites of 5-LOX were analyzed by reverse-phase high-performance liquid chromatography as well as by liquid chromatography-electrospray ionization-tandem mass spectrometry. The incubation of 5-LOX with the MPO-derived oxidants significantly changed the product profile of 5-LOX. Thereby, HOCl and HOBr increased the ratio of 5-H(p)ETE to 6-trans-LTB4 in a concentration-dependent manner. At low oxidant concentrations, there was a strong decrease in the yield of 6-trans-LTB4, whereas 5-HpETE did not change or increased. Additionally, the formation of 8-HpETE and 12-HpETE by 5-LOX rose slightly with increasing HOCl and HOBr. Comparable results were obtained with the MPO-H2O2-Cl– system when glucose oxidase and glucose were applied as a source of H2O2. This was necessary because of a strong impairment of 5-LOX activity by H2O2. In summary, MPO-derived oxidants showed a considerable impact on 5-LOX, impairing the epoxidation of 5-HpETE, whereas the hydroperoxidation of arachidonic acid was unaffected. Apparently, this was caused by an oxidative modification of critical amino acid residues of 5-LOX. Further work is necessary to assess the specific type and position of oxidation in the substrate-binding cavity of 5-LOX and to specify whether this interaction between 5-LOX and MPO-derived oxidants also takes place in stimulated neutrophils.
24

Adjuvant Hormonal Treatment for Prostate Cancer: The Bicalutamide Early Prostate Cancer Program

Wirth, Manfred P., Fröhner, Michael January 2003 (has links)
Adjuvant hormonal therapy has been demonstrated to be able to delay disease progression in nonmetastatic prostate cancer. To date, however, a favorable impact on survival has only been demonstrated in lymph-node-positive disease and in external-beam radiotherapy series with locally advanced and probably mainly micrometastatic tumors. The Bicalutamide Early Prostate Cancer Program is the largest study under way to define the role of adjuvant treatment in early prostate cancer and identify subgroups of patients likely to benefit from immediate hormonal therapy. At the time of the most recently published analysis, the risk of objective clinical progression was significantly reduced in the bicalutamide arm (hazards ratio 0.58, 95% confidence interval 0.51–0.66, p < 0.0001). However, further maturation of data is needed to see whether this difference will lead to a survival advantage. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
25

Treatment of Locally Advanced Prostate Cancer – The Case for Radical Prostatectomy

Hakenberg, Oliver W., Fröhner, Michael, Wirth, Manfred P. January 2006 (has links)
The treatment of clinically locally advanced prostate carcinoma (stage cT3) remains controversial. One of the main reasons for this controversy results from the substantial staging error attached to the clinical diagnosis cT3 with overstaged T2 tumors and understaged node-positive cases. Treatment options in this situation include radical prostatectomy, external beam radiotherapy, immediate or delayed androgen deprivation treatment and the so-called ‘watchful waiting’. Acceptable and often surprisingly good tumor-specific survival rates have been reported for radical prostatectomy in pT3 series – based on good clinical case selection – approaching those of pT2 series. In lymph node-positive pT3 cases, adjuvant hormone deprivation seems to prolong survival which it does not in lymph node-negative pT3 disease. A benefit of adjuvant external beam radiotherapy after radical prostatectomy for pT3 cases in prolonging overall survival has not been shown, despite the fact that it can prevent or delay biochemical and local recurrence. External beam radiotherapy as the only treatment for cT3 disease results in unfavorable tumor-specific survival rates, which can be significantly improved with adjuvant hormonal treatment with LHRH agonists. If, in case of advanced age and/or significant comorbidity, primary hormonal treatment is chosen, early hormonal deprivation therapy seems to offer marginal benefits in survival compared to delayed treatment. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
26

Perspectives in Adjuvant Treatment of Prostate Cancer

Wirth, Manfred P., Fröhner, Michael January 2002 (has links)
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
27

Relationship of Comorbidity, Age and Perioperative Complications in Patients Undergoing Radical Prostatectomy

Fröhner, Michael, Litz, Rainer, Manseck, Andreas, Hakenberg, Oliver W., Leike, Steffen, Albrecht, D.-Michael, Wirth, Manfred P. January 2001 (has links)
Objectives: To investigate the prevalence and distribution of comorbidity and its association with perioperative complications in patients undergoing radical prostatectomy (RPE). Methods: In 431 unselected RPE patients, the American Society of Anesthesiologists Physical Status classification (ASA-PS), the New York Heart Association classification of cardiac insufficiency (NYHA), the classification of angina pectoris of the Canadian Cardiovascular Society (CCS), height, weight, the body mass index (BMI), and the number of concomitant diseases (NCD) were assessed and related to perioperative cardiovascular complications. Results: In RPE patients less than 70 years old, comorbidity rose nearly continuously with increasing age. However, after reaching an age of 70 years, the proportion of NYHA-0 patients increased (60–64 years, 86%; 65–69 years, 85%; ≥70 years, 87%). Furthermore, the severe comorbidities decreased in patients selected for RPE aged 70 or more years. There was a nonsignificant trend towards higher comorbidity in patients with perioperative cardiovascular complications. Conclusions: These data suggest that documentation of the distribution of ASA-PS, CCS, NYHA and of concomitant diseases might be helpful to characterize the general health status and the degree of selection of prostate cancer treatment populations especially in series with a high portion of patients aged 70 or more years. Concerning perioperative complications, the individual predictive value of comorbidity seems to be poor in the radical prostatectomy setting. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
28

Is Systematic Sextant Biopsy Suitable for the Detection of Clinically Significant Prostate Cancer?

Manseck, Andreas, Fröhner, Michael, Oehlschläger, Sven, Hakenberg, Oliver W., Friedrich, Katrin, Theissig, Franz, Wirth, Manfred P. January 2000 (has links)
Background: The optimal extent of the prostate biopsy remains controversial. There is a need to avoid detection of insignificant cancer but not to miss significant and curable tumors. In alternative treatments of prostate cancer, repeated sextant biopsies are used to estimate the response. The aim of this study was to investigate the reliability of a repeated systematic sextant biopsy as the standard biopsy technique in patients with significant tumors which are being considered for curative treatment. Methods: Systematic sextant biopsy was performed in vitro in 92 radical prostatectomy specimens. Of these patients, 81 (88.0%) had palpable lesions. Results: Of the 92 investigated patients, 70 (76.1%) had potentially curable pT2-3pN0 prostate cancers. In these patients, the cancer was detected only in 72.9% of cases by a repeated in vitro biopsy. In the pT2 tumors, there was a detection rate of only 66.7%. Conclusions: This study underlines the fact that a considerable number of significant and potentially curable tumors remain undetected by the conventional sextant biopsy. A negative sextant biopsy does not rule out significant prostate cancer. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
29

Curative Treatment of Prostate Cancer

Wirth, Manfred P., Hakenberg, Oliver W. January 1999 (has links)
The guidelines for the curative treatment of prostate cancer presented by the German Society of Urology are discussed. They are based on the current knowledge of the outcomes of surgical and radiotherapeutic treatment for prostate cancer. Radical prostatectomy is recommended as the first-line treatment for organ-confined prostate cancer in patients with an individual life expectancy of at least 10 years. Radiotherapy can be considered as an alternative treatment modality, although current knowledge does not allow a definite assessment of the relative value of radiotherapy compared to radical prostatectomy. Locally advanced cT3 prostate cancer is overstaged in about 20% and curative treatment is possible in selected cases. Guidelines represent rules based on the available evidence. This implies that exceptions must be made whenever appropriate and that guidelines have to be reviewed regularly as new information becomes available. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
30

Biographien jüdischer Frauen: Rosa Luxemburg (1871-1919)

Schütrumpf, Jörg 06 December 2019 (has links)
No description available.

Page generated in 0.0401 seconds