Halogen-Kupfer-Austausch mit Kupferhypersilanid und Organylhalogeniden

Die Reaktion von Kupfertris(trimathylsilyl)silan (= Hypersilylkupfer, CuHyp) mit Iodoorganylverbindungen sollte analog zum Ullmann-Protokoll zum Halogen-Nukleophil-Austausch führen. Tatsächlich beobachteten wir zumeist die Bildung von Cuprio-Organylen, isolierbar in Form von mehrkernigen Neutralkomplexen aus dem Produkt und weiteren Äquivalenten von Hypersilylkupfer. Nach Zugabe von (weichen) Basen wie Trimethylphosphan kam es zur Auflösung dieser Komplexe und zur Bildung der erwarteten Silylorganyle. Von der systematischen Variation der eingesetzten Arene, Alkene und Alkine sowie ihrer Liganden versprachen wir uns tiefere Einsicht in die mechanistischen Zusammenhänge. Neben dem üblichen Halogen-Kupfer-Autausch konnten wir bei orthosubstituierten, bzw. zusätzlich tetramethylsubstituierten Diiodarenen einen einfachen Iod-Siyl-Autausch beobachten (vermutlich über Arinzwischenstufen), für Alkinedukte sogar eine doppelte Silylierung. Tatsächlich zeigen quantenchemische Berechnungen für CuHyp-Iodoorganyl-Systeme eine klare Präferenz von ullmannartigen Verläufen; andererseits führte Basenzugabe erst nachträglich zur Bildung von Ullmann-Produkten über die Auflösung der primären Komplexe. Innerhalb der üblicherweise gebildeten mehrkernigen Komplexe kommen Bindungen durch die Wechselwirkung unbesetzter σ*-Molekülorbitalee am Kupferzentrum von CuHyp und elektronenreichen bindenden Orbitalen in den Kupferorganyleinheiten zustande. Freie Elektronenpaare am Phosphor bei PMe3 könnten analog die Auflösung der Neutralkomplexe und die Bildung von vierkernigen Kupfer(III)-Intermediaten zwischen den Kupferorganyleinheiten und Iodsilan in der Lösung bewirken, die aufgrund ihrer strukturellen und energetischen Besonderheiten zu den erwarteten Ullmann-Produkten weiterreagieren würden. Die beobachteten Primärreaktionen verliefen dann offensichtlich über vergleichbare, aber unterschiedlich strukturierte Intermediate, vermutlich aufgrund der Tatsache, dass das eingesetzte CuHyp als Trimer vorliegt. Diese Annahme wird durch die direkte Silylierung von Iodalkinen gestützt, deren Dreifachbindungen möglicherweise als interne Base die trimeren in monomere CuHyp-Einheiten überführen. In eine ähnliche Richtung wäre die jüngst berichtete direkte Silylierung von Allylen bei Anwesenheit von elektronenreichen CN-Gruppen zu deuten.

Process-based modelling of lichens and bryophytes and their role in global biogeochemical cycles

This thesis presents a process-based modelling approach to quantify carbon uptake by lichens and bryophytes at the global scale. Based on the modelled carbon uptake, potential global rates of nitrogen fixation, phosphorus uptake and chemical weathering by the organisms are estimated. In this way, the significance of lichens and bryophytes for global biogeochemical cycles can be assessed. The model uses gridded climate data and key properties of the habitat (e.g. disturbance intervals) to predict processes which control net carbon uptake, namely photosynthesis, respiration, water uptake and evaporation. It relies on equations used in many dynamical vegetation models, which are combined with concepts specific to lichens and bryophytes, such as poikilohydry or the effect of water content on CO2 diffusivity. To incorporate the great functional variation of lichens and bryophytes at the global scale, the model parameters are characterised by broad ranges of possible values instead of a single, globally uniform value. The predicted terrestrial net uptake of 0.34 to 3.3 Gt / yr of carbon and global patterns of productivity are in accordance with empirically-derived estimates. Based on the simulated estimates of net carbon uptake, further impacts of lichens and bryophytes on biogeochemical cycles are quantified at the global scale. Thereby the focus is on three processes, namely nitrogen fixation, phosphorus uptake and chemical weathering. The presented estimates have the form of potential rates, which means that the amount of nitrogen and phosphorus is quantified which is needed by the organisms to build up biomass, also accounting for resorption and leaching of nutrients. Subsequently, the potential phosphorus uptake on bare ground is used to estimate chemical weathering by the organisms, assuming that they release weathering agents to obtain phosphorus. The predicted requirement for nitrogen ranges from 3.5 to 34 Tg / yr and for phosphorus it ranges from 0.46 to 4.6 Tg / yr. Estimates of chemical weathering are between 0.058 and 1.1 km³ / yr of rock. These values seem to have a realistic order of magnitude and they support the notion that lichens and bryophytes have the potential to play an important role for global biogeochemical cycles.

Methodenentwicklung zur Charakterisierung von metallischen Nanopartikeln und deren potentieller Einsatz bei der Analyse von Biomolekülen mittels ICP-MS Kopplungstechniken

Die qualitative und quantitative Analyse von Biomolekülen hat in den letzten Jahren und Jahrzehnten immer mehr an Bedeutung gewonnen. Durch das Aufkommen und die kontinuierliche Weiterentwicklung neuer Separations- und Detektionsmethoden und deren Verbindung miteinander zu leistungsfähigen Einheiten, erlangte man Schritt für Schritt neue Erkenntnisse bei ihrer Untersuchung. Die Elementmassenspektrometrie als nachweisstarke Detektionsmethode wird von vielen wissenschaftlichen Arbeitsgruppen bei der Trennung und Quantifizierung von Proteinen und Metalloproteinen mittels Detektion der in den Biomolekülen vorkommenden Metalle und Heteroatome angewendet. Heteroatome (z.B. Schwefel, Phosphor) haben im Plasma des ICP-MS (inductively coupled plasma - mass spectrometer) schlechte Ionisationseigenschaften und dementsprechend deutlich höhere Nachweisgrenzen als Metalle. Ein Ansatz, schlecht oder nicht detektierbare Verbindungen (also solche, die keine Metalle oder Heteroatome enthalten) mit dem ICP-MS sichtbar zu machen, ist die Markierung der selbigen mit Metallionen oder -cluster. rnIn dieser Arbeit ist es gelungen, der Analyse ganz unterschiedlicher Substanzklassen, zum einen metallische Nanopartikel und zum anderen Proteine, neue Impulse zu geben und zukünftiges Potential bei der Anwendung gekoppelter Techniken zur Separation und Detektion aufzuzeigen. Durch die Verwendung einer alten, aber neu konzipierten Trenntechnik, der Gelelektrophorese (GE), und deren Kopplung an einen modernen Detektor, dem ICP-MS, kann die für die Proteinanalytik weit verbreitete Gelelektrophorese ihr enormes Potential bei der Trennung verschiedenster Verbindungsklassen mit der exzellenten Nachweisstärke und Elementspezifität des ICP-MS verbinden und dadurch mit deutlich weniger Arbeitsaufwand als bisher qualitative und auch quantitative Ergebnisse produzieren. Bisher war dies nur mit großem präparativem Aufwand unter Verwendung der laser ablation möglich. Bei der Analyse von Nanopartikeln konnte aufgezeigt werden, dass durch die GE-ICP-MS-Kopplung aufgrund der guten Trenneigenschaften der GE vorhandene Spezies bzw. Fraktionen voneinander separiert werden und mit Hilfe des ICP-MS Informationen auf atomarem Niveau gewonnen werden können. Es war möglich, das atomare Verhältnis der Metallatome im Kern und der Schwefelatome in der Ligandenhülle eines Nanopartikels zu bestimmen und damit die Größe des Partikels abzuschätzen. Auch konnte die Anzahl der Goldatome in einem dem Schmid-Cluster ähnlichen Nanopartikel bestimmt werden, was vorher nur mit Hilfe von MALDI-TOF möglich war. Bei der Analyse von Biomolekülen konnte auf einfache Weise der Phosphorylierungsgrad verschiedener Proteine bestimmt werden. Auch bei kleinen Molekülen erzielt die Gelelektrophorese ausgezeichnete Trennergebnisse, wie z. B. bei der Analyse verschiedener Brom- und Iodspezies.rnDie stöchiometrische Kopplung eines Proteins an einen Nanopartikel, ohne eine der beiden Verbindungen in einem größeren Maße zu verändern, stellte jedoch eine Herausforderung dar, die im Rahmen dieser Arbeit nicht vollständig gelöst werden konnte. Verschiedene Ansätze zur Kopplung der beiden Substanzen wurden erprobt, jedoch führte keine zu dem gewünschten Ergebnis einer stöchiometrisch vollständigen und spezifischen Modifikation eines Proteins mit einem Nanopartikel. Durch das Potential der GE-ICP-MS-Kopplung bei der Analyse beider Substanz-klassen und dem Beweis der Praktikabilität und Zuverlässigkeit der Methode ist jedoch der Grundstein für weitere Forschungen auf diesem Gebiet gelegt worden. Ist eine geeignete chemische Kopplung der beiden Substanzklassen gefunden und beherrscht, steht auf analytischer Seite eine leistungsstarke Kombination aus Trennung und Detektion zur Verfügung, um die Quantifizierung von Proteinen entscheidend zu verbessern.rn

Osseointegration of hollow cylinder based spinal implants in normal and osteoporotic vertebrae: a sheep study

INTRODUCTION: Osteoporosis is not only responsible for an increased number of metaphyseal and spinal fractures but it also complicates their treatment. To prevent the initial loosening, we developed a new implant with an enlarged implant/bone interface based on the concept of perforated, hollow cylinders. We evaluated whether osseointegration of a hollow cylinder based implant takes place in normal or osteoporotic bone of sheep under functional loading conditions during anterior stabilization of the lumbar spine. MATERIALS AND METHODS: Osseointegration of the cylinders and status of the fused segments (ventral corpectomy, replacement with iliac strut, and fixation with testing implant) were investigated in six osteoporotic (age 6.9 +/- 0.8 years, mean body weight 61.1 +/- 5.2 kg) and seven control sheep (age 6.1 +/- 0.2 years, mean body weight 64.9 +/- 5.7 kg). Osteoporosis was introduced using a combination protocol of ovariectomy, high-dose prednisone, calcium and phosphor reduced diet and movement restriction. Osseointegration was quantified using fluorescence and conventional histology; fusion status was determined using biomechanical testing of the stabilized segment in a six-degree-of-freedom loading device as well as with radiological and histological staging. RESULTS: Intact bone trabeculae were found in 70% of all perforations without differences between the two groups (P = 0.26). Inside the cylinders, bone volume/total volume was significantly higher than in the control vertebra (50 +/- 16 vs. 28 +/- 13%) of the same animal (P<0.01), but significantly less (P<0.01) than in the near surrounding (60 +/- 21%). After biomechanical testing as described in Sect. "Materials and methods", seven spines (three healthy and four osteoporotic) were classified as completely fused and six (four healthy and two osteoporotic) as not fused after a 4-month observation time. All endplates were bridged with intact trabeculae in the histological slices. CONCLUSIONS: The high number of perforations, filled with intact trabeculae, indicates an adequate fixation; bridging trabeculae between adjacent endplates and tricortical iliac struts in all vertebrae indicates that the anchorage is adequate to promote fusion in this animal model, even in the osteoporotic sheep.

Should 3K zoom function be used for detection of pneumothorax in cesium iodide/amorphous silicon flat-panel detector radiographs presented on 1K-matrix soft copies?

The purpose of the study was to evaluate observer performance in the detection of pneumothorax with cesium iodide and amorphous silicon flat-panel detector radiography (CsI/a-Si FDR) presented as 1K and 3K soft-copy images. Forty patients with and 40 patients without pneumothorax diagnosed on previous and subsequent digital storage phosphor radiography (SPR, gold standard) had follow-up chest radiographs with CsI/a-Si FDR. Four observers confirmed or excluded the diagnosis of pneumothorax according to a five-point scale first on the 1K soft-copy image and then with help of 3K zoom function (1K monitor). Receiver operating characteristic (ROC) analysis was performed for each modality (1K and 3K). The area under the curve (AUC) values for each observer were 0.7815, 0.7779, 0.7946 and 0.7066 with 1K-matrix soft copies and 0.8123, 0.7997, 0.8078 and 0.7522 with 3K zoom. Overall detection of pneumothorax was better with 3K zoom. Differences between the two display methods were not statistically significant in 3 of 4 observers (p-values between 0.13 and 0.44; observer 4: p = 0.02). The detection of pneumothorax with 3K zoom is better than with 1K soft copy but not at a statistically significant level. Differences between both display methods may be subtle. Still, our results indicate that 3K zoom should be employed in clinical practice.

Comparison of different radiography systems in an experimental study for detection of forearm fractures and evaluation of the Müller-AO and Frykman classification for distal radius fractures

OBJECTIVES: We sought to compare the diagnostic performance of screen-film radiography, storage-phosphor radiography, and a flat-panel detector system in detecting forearm fractures and to classify distal radius fractures according to the Müller-AO and Frykman classifications compared with the true extent, depicted by anatomic preparation. MATERIALS AND METHODS: A total of 71 cadaver arms were fractured in a material testing machine creating different fractures of the radius and ulna as well as of the carpal bones. Radiographs of the complete forearm were evaluated by 3 radiologists, and anatomic preparation was used as standard of reference in a receiver operating curve analysis. RESULTS: The highest diagnostic performance was obtained for the detection of distal radius fractures with area under the receiver operating curve (AUC) values of 0.959 for screen-film radiography, 0.966 for storage-phosphor radiography, and 0.971 for the flat-panel detector system (P > 0.05). Exact classification was slightly better for the Frykman (kappa values of 0.457-0.478) compared with the Müller-AO classification (kappa values of 0.404-0.447), but agreement can be considered as moderate for both classifications. CONCLUSIONS: The 3 imaging systems showed a comparable diagnostic performance in detecting forearm fractures. A high diagnostic performance was demonstrated for distal radius fractures and conventional radiography can be routinely performed for fracture detection. However, compared with anatomic preparation, depiction of the true extent of distal radius fractures was limited and the severity of distal radius fractures tends to be underestimated.

Flame Synthesis of Complex Fluoride-Based Nanoparticles as Upconversion Phosphors

Recent improvements in precursor chemistry, reactor geometry and run conditions extend the manufacturing capability of traditional flame aerosol synthesis of oxide nanoparticles to metals, alloys and inorganic complex salts. As an example of a demanding composition, we demonstrate here the one-step flame synthesis of nanoparticles of a 4-element non-oxide phosphor for upconversion applications. The phosphors are characterized in terms of emission capability, phase purity and thermal phase evolution. The preparation of flame-made beta-NaYF4 with dopants of Yb, Tm or Yb, Er furthermore illustrates the now available nanoparticle synthesis tool boxes based on modified flamespray synthesis from our laboratories at ETH Zurich. Since scaling concepts for flame synthesis, including large-scale filtration and powder handling, have become available commercially, the development of industrial applications of complex nanoparticles of metals, alloys or most other thermally stable, inorganic compounds can now be considered a feasible alternative to traditional top-down manufacturing or liquid-intense wet chemistry.

Optimizing infrared to near infrared upconversion quantum yield of β-NaYF4:Er3+ in fluoropolymer matrix for photovoltaic devices

The present study reports for the first time the optimization of the infrared (1523 nm) to near-infrared (980 nm) upconversion quantum yield (UC-QY) of hexagonal trivalent erbium doped sodium yttrium fluoride (β-NaYF4:Er3+) in a perfluorocyclobutane (PFCB) host matrix under monochromatic excitation. Maximum internal and external UC-QYs of 8.4% ± 0.8% and 6.5% ± 0.7%, respectively, have been achieved for 1523 nm excitation of 970 ± 43 Wm−2 for an optimum Er3+ concentration of 25 mol% and a phosphor concentration of 84.9 w/w% in the matrix. These results correspond to normalized internal and external efficiencies of 0.86 ± 0.12 cm2 W−1 and 0.67 ± 0.10 cm2 W−1, respectively. These are the highest values ever reported for β-NaYF4:Er3+ under monochromatic excitation. The special characteristics of both the UC phosphor β-NaYF4:Er3+ and the PFCB matrix give rise to this outstanding property. Detailed power and time dependent luminescence measurements reveal energy transfer upconversion as the dominant UC mechanism.

Comparison of two fiber-optical temperature measurement systems in magnetic fields up to 9.4 Tesla.

PURPOSE Precise temperature measurements in the magnetic field are indispensable for MR safety studies and for temperature calibration during MR-guided thermotherapy. In this work, the interference of two commonly used fiber-optical temperature measurement systems with the static magnetic field B0 was determined. METHODS Two fiber-optical temperature measurement systems, a GaAs-semiconductor and a phosphorescent phosphor ceramic, were compared for temperature measurements in B0 . The probes and a glass thermometer for reference were placed in an MR-compatible tube phantom within a water bath. Temperature measurements were carried out at three different MR systems covering static magnetic fields up to B0  = 9.4T, and water temperatures were changed between 25°C and 65°C. RESULTS The GaAs-probe significantly underestimated absolute temperatures by an amount related to the square of B0 . A maximum difference of ΔT = -4.6°C was seen at 9.4T. No systematic temperature difference was found with the phosphor ceramic probe. For both systems, the measurements were not dependent on the orientation of the sensor to B0 . CONCLUSION Temperature measurements with the phosphor ceramic probe are immune to magnetic fields up to 9.4T, whereas the GaAs-probes either require a recalibration inside the MR system or a correction based on the square of B0 . Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.

Biotic and abiotic controls of nitrogen and phosphorus cycling in Central European forests

The functioning and services of Central European forests are threatened by global change and a loss of biodiversity. Nutrient cycling as a key forest function is affected by biotic drivers (e.g., dominant tree species, understory plants, soil organisms) that interact with abiotic conditions (e.g., climate, soil properties). In contrast to grassland ecosystems, evidence for the relationship of nutrient cycles and biodiversity in forests is scarce because the structural complexity of forests limits experimental control of driving factors. Alternatively, observational studies along gradients in abiotic conditions and biotic properties may elucidate the role of biodiversity for forest nutrient cycles. This thesis aims to improve the understanding of the functional importance of biodiversity for nutrient cycles in forests by analyzing water-bound fluxes of nitrogen (N) and phosphorus (P) along gradients in biodiversity in three regions of Germany. The tested hypotheses included: (1) temperate forest canopies retain atmospheric N and retention increases with increasing plant diversity, (2) N release from organic layers increases with resource availability and population size of decomposers but N leaching decreases along a gradient in plant diversity, (3) P leaching from forest canopies increases with improved P supply from recalcitrant P fractions by a more diverse ectomycorrhizal fungal community. In the canopies of 27 forest stands from three regions, 16 % to 51 % of atmospheric N inputs were retained. Regional differences in N retention likely resulted from different in N availability in the soil. Canopy N retention was greater in coniferous than in beech forests, but this was not the case on loessderived soils. Nitrogen retention increased with increasing tree and shrub diversity which suggested complementary aboveground N uptake. The strength of the diversity effect on canopy N uptake differed among regions and between coniferous and deciduous forests. The N processing in the canopy directly coupled back to N leaching from organic layers in beech forests because throughfall-derived N flushed almost completely through the mull-type organic layers at the 12 studied beech sites. The N release from organic layers increased with stand basal area but was rather low (< 10 % of annual aboveground litterfall) because of a potentially high microbial N immobilization and intensive incorporation of litter into the mineral soil by bioturbation. Soil fauna biomass stimulated N mineralization through trophic interactions with primary producers and soil microorganisms. Both gross and net leaching from organic layers decreased with increasing plant diversity. Especially the diversity but not the cover of herbs increased N uptake. In contrast to N, P was leached from the canopy. Throughfall-derived P was also flushed quickly through the mull-type organic layers and leached P was predominantly immobilized in non directly plant-available P fractions in the mineral soil. Concentrations of plant-available phosphate in mineral soil solution were low and P leaching from the canopy increased with increasing concentrations of the moderately labile P fraction in soil and increasing ectomycorrhiza diversity while leaf C:P ratios decreased. This suggested that tree P supply benefited from complementary mining of diverse mycorrhizal communities for recalcitrant P. Canopy P leaching increased in years with pronounced spring drought which could lead to a deterioration of P supply by an increasing frequency of drought events. This thesis showed that N and P cycling in Central European forests is controlled by a complex interplay of abiotic site conditions with biological processes mediated by various groups of organisms, and that diverse plant communities contribute to tightening the N cycle in Central European forests and that diverse mycorrhizal communities improve the limited P availability. Maintaining forest biodiversity seems essential to ensure forest services in the light of environmental change.

14-3-3 zeta overexpression in early stage breast disease and tumor progression

Recent progress in diagnostic tools allows many breast cancers to be detected at an early pre-invasive stage. Thus, a better understanding of the molecular basis of early breast cancer progression is essential. 14-3-3 is a family of highly conserved and ubiquitously expressed proteins that are expressed in all eukaryotic organisms. In mammals there are seven isoforms, which bind to phosphor-serine/threonine residues regulating essential cellular processes such as signal transduction, cell cycle progression, and apoptosis. Our laboratory has discovered that a particular 14-3-3 family member, Zeta, is overexpressed in over 40% of breast tumor tissues. Furthermore, I examined the stage of breast disease in which 14-3-3ζ overexpression occurs and found that increased expression of 14-3-3ζ begins at the stage of atypical ductal hyperplasia, a very early stage of breast disease that confers increased risk for progress toward breast cancer. To determine whether 14-3-3ζ overexpression is a decisive early event in breast cancer, I overexpressed 14-3-3ζ in MCF10A cells, a non-transformed mammary epithelial cell (MEC) line and examined its impact on acini formation in a three dimensional (3D) culture model which simulates a basic unit of structure in the mammary gland. I discovered that 14-3-3ζ overexpression severely disrupted the acini architecture resulting in the disruption of polarity and luminal filling. Both are critical morphological events in the pre-neoplastic breast disease. This thesis focuses on the molecular mechanism of luminal filling. Proper lumen formation is a result of anoikis, a specific type apoptosis of cells not attached to the basement membrane. I found that 14-3-3ζ overexpression conferred a resistance to anoikis. Additionally, 14-3-3ζ overexpression in MCF10A cells and in MECs from 14-3-3ζ transgenic mice reduced expression of p53, which is known to mediate anoikis. Mechanistically, 14-3-3ζ induced hyperactivation of the PI3K/Akt pathway which led to phosphorylation and translocation of the MDM2 to the nucleus resulting in increased p53 degradation. Ectopic expression of p53 restored luminal apoptosis in 14-3-3ζ overexpressing MCF10A acini in 3D cultures. These data suggest that 14-3-3ζ overexpression is a critical event in early breast disease and down-regulation of p53 is one of the mechanisms by which 14-3-3ζ alters MEC acini structure and may increase the risk of progression to breast cancer. ^

Color uniformity in spotligths - visual perception and system design

La iluminación con diodos emisores de luz (LED) está reemplazando cada vez en mayor medida a las fuentes de luz tradicionales. La iluminación LED ofrece ventajas en eficiencia, consumo de energía, diseño, tamaño y calidad de la luz. Durante más de 50 años, los investigadores han estado trabajando en mejoras LED. Su principal relevancia para la iluminación está aumentando rápidamente. Esta tesis se centra en un campo de aplicación importante, como son los focos. Se utilizan para enfocar la luz en áreas definidas, en objetos sobresalientes en condiciones profesionales. Esta iluminación de alto rendimiento requiere una calidad de luz definida, que incluya temperaturas ajustables de color correlacionadas (CCT), de alto índice de reproducción cromática (CRI), altas eficiencias, y colores vivos y brillantes. En el paquete LED varios chips de diferentes colores (rojo, azul, fósforo convertido) se combinan para cumplir con la distribución de energía espectral con alto CRI. Para colimar la luz en los puntos concretos deseados con un ángulo de emisión determinado, se utilizan blancos sintonizables y diversos colores de luz y ópticas secundarias. La combinación de una fuente LED de varios colores con elementos ópticos puede causar falta de homogeneidad cromática en la distribución espacial y angular de la luz, que debe resolverse en el diseño óptico. Sin embargo, no hay necesidad de uniformidad perfecta en el punto de luz debido al umbral en la percepción visual del ojo humano. Por lo tanto, se requiere una descripción matemática del nivel de uniformidad del color con respecto a la percepción visual. Esta tesis está organizada en siete capítulos. Después de un capítulo inicial que presenta la motivación que ha guiado la investigación de esta tesis, en el capítulo 2 se presentan los fundamentos científicos de la uniformidad del color en luces concentradas, como son: el espacio de color aplicado CIELAB, la percepción visual del color, los fundamentos de diseño de focos respecto a los motores de luz y ópticas no formadoras de imágenes, y los últimos avances en la evaluación de la uniformidad del color en el campo de los focos. El capítulo 3 desarrolla diferentes métodos para la descripción matemática de la distribución espacial del color en un área definida, como son la diferencia de color máxima, la desviación media del color, el gradiente de la distribución espacial de color, así como la suavidad radial y axial. Cada función se refiere a los diferentes factores que influyen en la visión, los cuales necesitan un tratamiento distinto que el de los datos que se tendrán en cuenta, además de funciones de ponderación que pre- y post-procesan los datos simulados o medidos para la reducción del ruido, la luminancia de corte, la aplicación de la ponderación de luminancia, la función de sensibilidad de contraste, y la función de distribución acumulativa. En el capítulo 4, se obtiene la función de mérito Usl para la estimación de la uniformidad del color percibida en focos. Se basó en los resultados de dos conjuntos de experimentos con factor humano realizados para evaluar la percepción visual de los sujetos de los patrones de focos típicos. El primer experimento con factor humano dio lugar al orden de importancia percibida de los focos. El orden de rango percibido se utilizó para correlacionar las descripciones matemáticas de las funciones básicas y la función ponderada sobre la distribución espacial del color, que condujo a la función Usl. El segundo experimento con factor humano probó la percepción de los focos bajo condiciones ambientales diversas, con el objetivo de proporcionar una escala absoluta para Usl, para poder así sustituir la opinión subjetiva personal de los individuos por una función de mérito estandarizada. La validación de la función Usl se presenta en relación con el alcance de la aplicación y condiciones, así como las limitaciones y restricciones que se realizan en el capítulo 5. Se compararon los datos medidos y simulados de varios sistemas ópticos. Se discuten los campos de aplicación , así como validaciones y restricciones de la función. El capítulo 6 presenta el diseño del sistema de focos y su optimización. Una evaluación muestra el análisis de sistemas basados en el reflector y la lente TIR. Los sistemas ópticos simulados se comparan en la uniformidad del color Usl, sensibilidad a las sombras coloreadas, eficiencia e intensidad luminosa máxima. Se ha comprobado que no hay un sistema único que obtenga los mejores resultados en todas las categorías, y que una excelente uniformidad de color se pudo alcanzar por la conjunción de dos sistemas diferentes. Finalmente, el capítulo 7 presenta el resumen de esta tesis y la perspectiva para investigar otros aspectos. ABSTRACT Illumination with light-emitting diodes (LED) is more and more replacing traditional light sources. They provide advantages in efficiency, energy consumption, design, size and light quality. For more than 50 years, researchers have been working on LED improvements. Their main relevance for illumination is rapidly increasing. This thesis is focused on one important field of application which are spotlights. They are used to focus light on defined areas, outstanding objects in professional conditions. This high performance illumination required a defined light quality including tunable correlated color temperatures (CCT), high color rendering index (CRI), high efficiencies and bright, vivid colors. Several differently colored chips (red, blue, phosphor converted) in the LED package are combined to meet spectral power distribution with high CRI, tunable white and several light colors and secondary optics are used to collimate the light into the desired narrow spots with defined angle of emission. The combination of multi-color LED source and optical elements may cause chromatic inhomogeneities in spatial and angular light distribution which needs to solved at the optical design. However, there is no need for perfect uniformity in the spot light due to threshold in visual perception of human eye. Therefore, a mathematical description of color uniformity level with regard to visual perception is required. This thesis is organized seven seven chapters. After an initial one presenting the motivation that has guided the research of this thesis, Chapter 2 introduces the scientific basics of color uniformity in spot lights including: the applied color space CIELAB, the visual color perception, the spotlight design fundamentals with regards to light engines and nonimaging optics, and the state of the art for the evaluation of color uniformity in the far field of spotlights. Chapter 3 develops different methods for mathematical description of spatial color distribution in a defined area, which are the maximum color difference, the average color deviation, the gradient of spatial color distribution as well as the radial and axial smoothness. Each function refers to different visual influencing factors, and they need different handling of data be taken into account, along with weighting functions which pre- and post-process the simulated or measured data for noise reduction, luminance cutoff, the implementation of luminance weighting, contrast sensitivity function, and cumulative distribution function. In chapter 4, the merit function Usl for the estimation of the perceived color uniformity in spotlights is derived. It was based on the results of two sets of human factor experiments performed to evaluate the visual perception of typical spotlight patterns by subjects. The first human factor experiment resulted in the perceived rank order of the spotlights. The perceived rank order was used to correlate the mathematical descriptions of basic functions and weighted function concerning the spatial color distribution, which lead to the Usl function. The second human factor experiment tested the perception of spotlights under varied environmental conditions, with to objective to provide an absolute scale for Usl, so the subjective personal opinion of individuals could be replaced by a standardized merit function. The validation of the Usl function is presented concerning the application range and conditions as well as limitations and restrictions in carried out in chapter 5. Measured and simulated data of various optical several systems were compared. Fields of applications are discussed as well as validations and restrictions of the function. Chapter 6 presents spotlight system design and their optimization. An evaluation shows the analysis of reflector-based and TIR lens systems. The simulated optical systems are compared in color uniformity Usl , sensitivity to colored shadows, efficiency, and peak luminous intensity. It has been found that no single system which performed best in all categories, and that excellent color uniformity could be reached by two different system assemblies. Finally, chapter 7 summarizes the conclusions of the present thesis and an outlook for further investigation topics.

AVALIAÇÃO DA COMPRESSÃO DA IMAGEM DIGITAL DA TELERRADIOGRAFIA LATERAL NA REPRODUTIBILIDADE DA MARCAÇÃO DE PONTOS CEFALOMÉTRICOS

A imagem digital adquirida pelo sistema da placa de fósforo foto ativada é visualizada no monitor do computador em um formato denominado DICOM. Este formato ocupa muito espaço para armazenamento, o que dificulta o arquivamento e transmissão da imagem pela Internet. O objetivo deste estudo foi avaliar a influência da compressão JPEG, nos Fatores de Qualidade 100, 80 e 60 na reprodutibilidade da marcação de pontos cefalométricos em imagens de telerradiografias em norma lateral comparadas com o formato DICOM. A amostra consistiu de 120 imagens de telerradiografias em norma lateral obtidas a partir de 30 indivíduos, dos quais se obteve uma radiografia digital no formato DICOM. Essas imagens foram convertidas para o formato JPEG. Após o cegamento e randomização da amostra, três Ortodontistas calibrados marcaram a localização de 12 pontos cefalométricos em cada imagem utilizando o sistema de coordenadas X e Y. Esse procedimento foi repetido após 1 mês. A reprodutibilidade intra e inter observador foi calculada usando o teste de correlação intraclasse. Para comparação entre os grupos de compressão e DICOM na reprodutibilidade de marcação dos pontos utilizou se a Análise de Variância (ANOVA) a um critério para medidas repetidas. Os resultados mostraram que as marcações dos pontos cefalométricos foram bastante reprodutíveis, exceto para o ponto Órbita na coordenada X. Os diferentes formatos de arquivo mostraram estatisticamente iguais para cada ponto e eixo aferido. As compressões JPEG estudadas das imagens de telerradiografias em norma lateral não tiveram efeito na reprodutibilidade da marcação dos pontos cefalométricos testados.

AVALIAÇÃO DA COMPRESSÃO DA IMAGEM DIGITAL DA TELERRADIOGRAFIA LATERAL NA REPRODUTIBILIDADE DA MARCAÇÃO DE PONTOS CEFALOMÉTRICOS

A imagem digital adquirida pelo sistema da placa de fósforo foto ativada é visualizada no monitor do computador em um formato denominado DICOM. Este formato ocupa muito espaço para armazenamento, o que dificulta o arquivamento e transmissão da imagem pela Internet. O objetivo deste estudo foi avaliar a influência da compressão JPEG, nos Fatores de Qualidade 100, 80 e 60 na reprodutibilidade da marcação de pontos cefalométricos em imagens de telerradiografias em norma lateral comparadas com o formato DICOM. A amostra consistiu de 120 imagens de telerradiografias em norma lateral obtidas a partir de 30 indivíduos, dos quais se obteve uma radiografia digital no formato DICOM. Essas imagens foram convertidas para o formato JPEG. Após o cegamento e randomização da amostra, três Ortodontistas calibrados marcaram a localização de 12 pontos cefalométricos em cada imagem utilizando o sistema de coordenadas X e Y. Esse procedimento foi repetido após 1 mês. A reprodutibilidade intra e inter observador foi calculada usando o teste de correlação intraclasse. Para comparação entre os grupos de compressão e DICOM na reprodutibilidade de marcação dos pontos utilizou se a Análise de Variância (ANOVA) a um critério para medidas repetidas. Os resultados mostraram que as marcações dos pontos cefalométricos foram bastante reprodutíveis, exceto para o ponto Órbita na coordenada X. Os diferentes formatos de arquivo mostraram estatisticamente iguais para cada ponto e eixo aferido. As compressões JPEG estudadas das imagens de telerradiografias em norma lateral não tiveram efeito na reprodutibilidade da marcação dos pontos cefalométricos testados.

AVALIAÇÃO DA REPRODUTIBILIDADE DE PONTOS CEFALOMÉTRICOS NAS TELERRADIOGRAFIAS DIGITAIS EM NORMA LATERAL NOS FORMATOS DICOM, TIFF E JPEG

A imagem radiográfica digital adquirida pelo sistema de placa de fósforo foto ativada é normalmente visualizada no monitor do computador no formato DICOM, caracterizado pela alta resolução das imagens. Como este formato ocupa muito espaço para armazenamento, as imagens digitais são submetidas a uma compressão, que otimiza a capacidade de espaço dos computadores e reduz o tempo de transmissão pela Internet. O objetivo desse estudo foi avaliar a influência da compressão TIFF e JPEG na reprodutibilidade intra e interexaminador da marcação de pontos cefalométricos em imagens de telerradiografias em norma lateral comparadas com o formato DICOM. A amostra consistiu de 90 imagens de telerradiografias obtidas a partir de 30 indivíduos, dos quais se obteve uma radiografia digital exibida no formato DICOM. Estas imagens foram convertidas para os formatos JPEG, com Fator de Qualidade 80 e TIFF. Após o cegamento e randomização da amostra, três ortodontistas calibrados marcaram a localização de 15 pontos cefalométricos em cada imagem utilizando o sistema de coordenadas x e y. Os resultados mostraram que as marcações dos pontos cefalométricos apresentaram concordância de reprodutibilidade tanto intra como interexaminador, exceto para os pontos Go, Po, Or, B e Pog . Os diferentes formatos de arquivo mostraram resultados estatisticamente semelhantes para cada ponto e eixo aferido. As compressões JPEG e TIFF estudadas não tiveram efeito, em imagens de telerradiografias em norma lateral, na reprodutibilidade intra e interexaminadores da marcação dos pontos cefalométricos testados.(AU)