Multidimensionale Segmentierung in Bildfolgen und Quantifizierung dynamischer Prozesse

Im Rahmen dieser interdisziplinären Arbeit habe ich Methoden der Bildverarbeitung entwickelt, um reproduzierbare, quantitative Aussagen über dynamische Phänomene zu ermöglichen. Der Anwendungsschwerpunkt liegt im Bereich von Biologie und Medizin. Die verarbeiteten Daten stammen aus konfokalen Mikroskopaufnahmen, die biologischen Strukturen wurden mit fluoreszierenden Markern gefärbt. Aufgrund eines schlechten Signal-zu-Rausch Verhältnisses mußte ich robuste Verfahren entwickelt. Geeignete Vorverarbeitungsschritte waren nötig um die Qualität der Bilder zu erhöhen. Ich entwickelte ein Verfahren, um sowohl 2D- als auch 3D-Objekte mit aktiven Konturen in Bildern zu segmentieren. Dabei konnte ich in 2D zeigen, daß der Bereich der Attraktion der aktiven B-spline Kontur durch ein spezielles externes Kräftefeld erhöht werden konnte. Dies stellt einen Vorteil gegenüber den bisherigen parametrischen aktiven Konturen dar, besonders dann, wenn die Initialkurve weit von dem zu segmentierenden Objekt gelegt wird. In 3D wurde von mir eine Methode vorgestellt, um mehrere Objekte separat zu segmentieren. Hier setzte ich für diesen Spezialfall der Zellteilung einen Clusteralgorithmus ein, um zuvor extrahierte Kantenpunkte den Objekten zuzuordnen. Damit konnte ich die Volumen- und Oberflächenveränderung quantifizieren. Um segmentierte Objekte in beliebigen Dimensionen über die Zeit zu verfolgen, wurde von mir ein Particle-Tracking Algorithmus auf der Grundlage einer Fuzzy-Entscheidungslogik entwickelt. Eine Reihe von Anwendungen aus der biologischen Grundlagenforschung veranschaulichen die Wirkungsweise der entwickelten Methoden

Bestimmung von Transferfaktoren Boden - Pflanze von natürlichen Radionukliden

In der Arbeit werden nach einer detaillierten Beschreibung der eingesetzten Böden mit erhöhter Konzentration an den Radionukliden 210Pb, 226Ra, 227Ac, 230Th und 238U und der angewandten Analysenverfahren eine umfangreiche Übersicht über die Transferfaktoren Boden - Pflanze für die einzelnen Pflanzenteile der in der menschlichen Ernährung genutzten Gemüse und in Futterpflanzen vorgestellt. Die gammaspektrometrischen Bestimmungen von geringen Radioaktivitäten wurden einem Untertagemesslabor durchgeführt. Die Unterschiede in den Transferfaktoren für die Pflanzen und deren Teile und Böden und die Beziehungen zwischen Transferfaktoren und eluierbaren Anteilen der Böden, Pflanzenteile; sowie zwischen den radioaktiven Elementen Radium und Actinium und den Elementen Barium und Lanthan wurden dargestellt. Es wurde bei den Pflanzen eine Abnahme der Radioaktivität von der Wurzel über Stängel und Blatt zur Frucht festgestellt. Die Transferfaktoren für das bisher kaum bestimmten 227Ac ist relativ hoch und liegt in der Größenordnung der sehr konservativ angesetzten Richtwerte des Strahlenschutzes, während sie für die anderen Radionuklide weit unter den Richtwerten liegen.The used soils with enhanced activity of the radionuclides 210Pb, 226Ra, 227Ac, 230Th, and 238U and the analytical methods for the determination of soil-plant transfer factors are described and a survey of the obtained values for parts of plants used for human nutrition are presented. Gamma spectrometric determination of low radioactivities has been performed in an underground laboratory. For comparison the factors are determined for the plants of similar elements Ba for Ra and La for Ac. In all cases the values decreases from the roots over the leaves to the fruits. The values for 227Ac are relatively high and are in the magnitude of the „Richtwerte“ for radiation protection, in spite of the other radionuclides, which are lower than the „Richtwerte“

I-BEAT: New ultrasonic method for single bunch measurement of ion energy distribution

The shape of a wave carries all information about the spatial and temporal structure of its source, given that the medium and its properties are known. Most modern imaging methods seek to utilize this nature of waves originating from Huygens' principle. We discuss the retrieval of the complete kinetic energy distribution from the acoustic trace that is recorded when a short ion bunch deposits its energy in water. This novel method, which we refer to as Ion-Bunch Energy Acoustic Tracing (I-BEAT), is a generalization of the ionoacoustic approach. Featuring compactness, simple operation, indestructibility and high dynamic ranges in energy and intensity, I-BEAT is a promising approach to meet the needs of petawatt-class laser-based ion accelerators. With its capability of completely monitoring a single, focused proton bunch with prompt readout it, is expected to have particular impact for experiments and applications using ultrashort ion bunches in high flux regimes. We demonstrate its functionality using it with two laser-driven ion sources for quantitative determination of the kinetic energy distribution of single, focused proton bunches.Comment: Paper: 17 Pages, 3 figures Supplementary Material 16 pages, 7 figure

Mechanisms governing the pioneering and redistribution capabilities of the non-classical pioneer PU.1

Establishing gene regulatory networks during differentiation or reprogramming requires master or pioneer transcription factors (TFs) such as PU.1, a prototype master TF of hematopoietic lineage differentiation. To systematically determine molecular features that control its activity, here we analyze DNA-binding in vitro and genome-wide in vivo across different cell types with native or ectopic PU.1 expression. Although PU.1, in contrast to classical pioneer factors, is unable to access nucleosomal target sites in vitro, ectopic induction of PU.1 leads to the extensive remodeling of chromatin and redistribution of partner TFs. De novo chromatin access, stable binding, and redistribution of partner TFs both require PU.1's N-terminal acidic activation domain and its ability to recruit SWI/SNF remodeling complexes, suggesting that the latter may collect and distribute co-associated TFs in conjunction with the non-classical pioneer TF PU.1

Quantum phase transitions

In recent years, quantum phase transitions have attracted the interest of both theorists and experimentalists in condensed matter physics. These transitions, which are accessed at zero temperature by variation of a non-thermal control parameter, can influence the behavior of electronic systems over a wide range of the phase diagram. Quantum phase transitions occur as a result of competing ground state phases. The cuprate superconductors which can be tuned from a Mott insulating to a d-wave superconducting phase by carrier doping are a paradigmatic example. This review introduces important concepts of phase transitions and discusses the interplay of quantum and classical fluctuations near criticality. The main part of the article is devoted to bulk quantum phase transitions in condensed matter systems. Several classes of transitions will be briefly reviewed, pointing out, e.g., conceptual differences between ordering transitions in metallic and insulating systems. An interesting separate class of transitions are boundary phase transitions where only degrees of freedom of a subsystem become critical; this will be illustrated in a few examples. The article is aimed on bridging the gap between high-level theoretical presentations and research papers specialized in certain classes of materials. It will give an overview over a variety of different quantum transitions, critically discuss open theoretical questions, and frequently make contact with recent experiments in condensed matter physics.Comment: 50 pages, 7 figs; (v2) final version as publishe

I-BEAT: Ultrasonic method for online measurement of the energy distribution of a single ion bunch

The shape of a wave carries all information about the spatial and temporal structure of its source, given that the medium and its properties are known. Most modern imaging methods seek to utilize this nature of waves originating from Huygens' principle. We discuss the retrieval of the complete kinetic energy distribution from the acoustic trace that is recorded when a short ion bunch deposits its energy in water. This novel method, which we refer to as Ion-Bunch Energy Acoustic Tracing (I-BEAT), is a refinement of the ionoacoustic approach. With its capability of completely monitoring a single, focused proton bunch with prompt readout and high repetition rate, I-BEAT is a promising approach to meet future requirements of experiments and applications in the field of laser-based ion acceleration. We demonstrate its functionality at two laser-driven ion sources for quantitative online determination of the kinetic energy distribution in the focus of single proton bunches

Osteoarticular Infections in Pediatric Hospitals in Europe: A Prospective Cohort Study From the EUCLIDS Consortium

BACKGROUND: Pediatric osteoarticular infections (POAIs) are serious diseases requiring early diagnosis and treatment. METHODS: In this prospective multicenter cohort study, children with POAIs were selected from the European Union Childhood Life-threatening Infectious Diseases Study (EUCLIDS) database to analyze their demographic, clinical, and microbiological data. RESULTS: A cohort of 380 patients with POAIs, 203 with osteomyelitis (OM), 158 with septic arthritis (SA), and 19 with both OM and SA, was analyzed. Thirty-five patients were admitted to the Pediatric Intensive Care Unit; out of these, six suffered from shock, one needed an amputation of the right foot and of four left toes, and two had skin transplantation. According to the Pediatric Overall Performance Score, 36 (10.5%) showed a mild overall disability, 3 (0.8%) a moderate, and 1 (0.2%) a severe overall disability at discharge. A causative organism was detected in 65% (247/380) of patients. Staphylococcus aureus (S. aureus) was identified in 57.1% (141/247) of microbiological confirmed cases, including 1 (0.7%) methicillin-resistant S. aureus (MRSA) and 6 (4.2%) Panton-Valentine leukocidin (PVL)-producing S. aureus, followed by Group A Streptococcus (18.2%) and Kingella kingae (8.9%). K. kingae and PVL production in S. aureus were less frequently reported than expected from the literature. CONCLUSION: POAIs are associated with a substantial morbidity in European children, with S. aureus being the major detected pathogen. In one-third of patients, no causative organism is identified. Our observations show an urgent need for the development of a vaccine against S. aureus and for the development of new microbiologic diagnostic guidelines for POAIs in European pediatric hospitals

PESFOR-W: Improving the design and environmental effectiveness of woodlands for water Payments for Ecosystem Services

ABSTRACT: The EU Water Framework Directive aims to ensure restoration of Europe?s water bodies to ?good ecological status? by 2027. Many Member States will struggle to meet this target, with around half of EU river catchments currently reporting below standard water quality. Diffuse pollution from agriculture represents a major pressure, affecting over 90% of river basins. Accumulating evidence shows that recent improvements to agricultural practices are benefiting water quality but in many cases will be insufficient to achieve WFD objectives. There is growing support for land use change to help bridge the gap, with a particular focus on targeted tree planting to intercept and reduce the delivery of diffuse pollutants to water. This form of integrated catchment management offers multiple benefits to society but a significant cost to landowners and managers. New economic instruments, in combination with spatial targeting, need to be developed to ensure cost effective solutions - including tree planting for water benefits - are realised. Payments for Ecosystem Services (PES) are flexible, incentive-based mechanisms that could play an important role in promoting land use change to deliver water quality targets. The PESFOR-W COST Action will consolidate learning from existing woodlands for water PES schemes in Europe and help standardize approaches to evaluating the environmental effectiveness and cost-effectiveness of woodland measures. It will also create a European network through which PES schemes can be facilitated, extended and improved, for example by incorporating other ecosystem services linking with aims of the wider forestscarbon policy nexus