Weltklimapolitik im Kongobecken : Neue Chance oder Ökorente für die Eliten?

The objective with this Master’s thesis was to develop, implement and evaluate an iterative procedure for hierarchical clustering with good overall performance which also merges features of certain already described algorithms into a single integrated package. An accordingly built tool was then applied to an allergen IgE-reactivity data set. The finally implemented algorithm uses a hierarchical approach which illustrates the emergence of patterns in the data. At each level of the hierarchical tree a partitional clustering method is used to divide data into k groups, where the number k is decided through application of cluster validation techniques. The cross-reactivity analysis, by means of the new algorithm, largely arrives at anticipated cluster formations in the allergen data, which strengthen results obtained through previous studies on the subject. Notably, though, certain unexpected findings presented in the former analysis where aggregated differently, and more in line with phylogenetic and protein family relationships, by the novel clustering package

Moisture-induced stresses and distortions in spruce cross-laminates and composite laminates

The crosswise gluing of cross-laminated panels made of solid wood can cause problems when exposed to moisture variations. In the present study, the substitution of the spruce middle layer by a wood composite is tested for its influence on moisture-induced stresses and deformations in laboratory tests and numerical simulations. Furthermore, slits in the spruce middle layer were investigated. The hygroscopic warping due to a moisture gradient, stresses caused by moistening and cracks due to drying were studied. The results show larger warping in composite laminates compared to the spruce cross-laminate, which is governed by the modulus of elasticity of the middle layer. The in-plane swelling was found to be larger in composite laminates, while stresses were lower. The drying test discovered that cracks develop in the middle layer of spruce-medium density fiberboard laminates due to shear stresses and tensile stresses in the thickness direction. It was concluded that slits can be applied in the middle layer, as they have no significant influence on moisture-induced stresses but increase the thermal insulation. If the substitution of the spruce layer is required, the application of oriented strand board in the middle layer is recommende

Ethnic diversity, poverty and social trust in Germany: evidence from a behavioral measure of trust

Several scholars have concluded that ethnic diversity has negative consequences for social trust. However, recent research has called into question whether ethnic diversity per se has detrimental effects, or whether lower levels of trust in diverse communities simply reflect a higher concentration of less trusting groups, such as poor people, minorities, or immigrants. Drawing upon a nationally representative sample of the German population (GSOEP), we make two contributions to this debate. First, we examine how ethnic diversity at the neighborhood level-specifically the proportion of immigrants in the neighborhood-is linked to social trust focusing on the compositional effect of poverty. Second, in contrast to the majority of current research on ethnic diversity, we use a behavioral measure of trust in combination with fine-grained (zip-code level) contextual measures of ethnic composition and poverty. Furthermore, we are also able to compare the behavioral measure to a standard attitudinal trust question. We find that household poverty partially accounts for lower levels of trust, and that after controlling for income, German and non-German respondents are equally trusting. However, being surrounded by neighbors with immigrant background is also associated with lower levels of social trust

Finite element analysis of wood adhesive joints

Engineered wood products such as glulam or cross-laminated timber are widely established in the construction industry. Their structural behaviour and reliability clearly bases on the adhesive bonding. In order to understand and improve the performance of glued wood members a finite element modelling of standard single lap shear samples was carried out. A three-dimensional model of a longitudinal tensile-shear specimen with quasi-centric load application was developed. The main influences of wood and adhesive parameters on structural performance were identified. Therefore, variations of the elasticity, the annual ring angle, fibre angle, and the interface zone and their effect on the occurring stresses in the adhesive bond line were investigated numerically. The adhesive bond line is most significantly sensitive to the Young´s modulus of the adhesive itself. A variation of the fibre angle of the glued members in the standard test is an essential criterion and to be considered when preparing lap shear specimens. A model wit

Identification of moisture-induced stresses in cross-laminated wood panels from beech wood ( Fagus sylvatica L.)

The crosswise bonding of the layers in laminated solid wood panels results in internal stresses when the humidity varies. The layers hinder one another as a result of the anisotropy of wood. The purpose of this study was to determine the internal stress state in free and constrained swelling. The expansion properties in the three panel directions were measured. Furthermore, the swelling of samples was constrained while the resulting forces were recorded. Hygroscopic warping experiments were carried out inducing a climate gradient within the panels. Afterwards the stresses were calculated from released deformations and non-destructive measurements of the Young's modulus. The materials used were untreated and heat-treated beech wood, the latter modified in two levels. In addition to homogenously structured panels, treated top layers were combined with an untreated middle layer. Swelling, swelling pressure, warping and internal stresses considerably decreased from untreated to treated wood. If layers from treated and untreated material were combined, stresses and deformations increased as compared to the variants produced only from treated wood. It was concluded that the lower equilibrium moisture content of heat-treated beech wood improves its dimensional stability, which results in smaller deformation differences between the layers. Hence, the stresses were less distinctiv

Experimental and numerical determination of the hygroscopic warping of cross-laminated solid wood panels

The moisture-induced warping of three-layered cross-laminated solid wood panels made of Norway spruce was studied. The panels were exposed to different climate conditions at 65% and 100% relative humidity at the two panel faces. The results showed increasing cup deformation with an increasing relative thickness of the outer layers. The annual growth ring orientation was found to have a significant influence on the magnitude of the cup deformation. Measurements and numerical simulations of the moisture distribution within the panel were made in order to provide data for numerical simulations of the warping. A distinctive moisture profile with a conspicuous influence of the adhesive bond lines was found. The coefficient of diffusion of the adhesive bond lines was determined from the measurements and simulations. The mechanical material model used for the warping simulations takes into account elastic strain, moisture-induced swelling, and mechano-sorptive strain. The simulations showed good agreement with the warping test results. The most important material parameters for the cup deformation, which were identified in a parametric study of a panel with vertically oriented annual rings, are the moduli of elasticity and the swelling coefficients in the longitudinal and radial direction. Furthermore, the mechano-sorptive coefficient in radial direction was found to have a significant influence on war

Die Wechselbeziehung zwischen autoreaktiven T Zellen und alveolaren Typ II Epithelzellen in Entzündungs- und Toleranzreaktionen

It is well established, that the lung is an organ with tolerogenic properties to avoid an immunological collapse due to infection and inflammation. However, little is known about the mechanisms underlying peripheral tolerance induction in the lung. To dissect the immunological and molecular mechanisms underlying autoimmune-mediated lung disease, CD4+ T cell reactivity to a lung-specific antigen was studied by transgenic expression of hemagglutinin (HA) in alveolar type II epithelial cells. Concomitant expression of HA and a MHC class II-restricted T cell receptor specific for HA in double transgenic mice resulted in a severe immune-mediated interstitial lung disease. Despite aggressive and rapid progression of inflammation in lung of young mice, the pulmonary inflammation reached a plateau state in elder mice, suggesting the induction of peripheral tolerance mechanisms. Extensive immunological characterization of self-reactive CD4+ T cells isolated from the inflamed lung and global gene expression profiling suggested the induction of functional regulatory T cells in the site of inflammation. Establishing a new protocol to isolate highly pure and vital alveolar type II epithelial cells ex vivo, enabled us to characterize the role of alveolar type II epithelial cells in disease progression and immune regulation. We show that alveolar type II epithelial cells are capable to induce antigen-specific T cell proliferation. Moreover, alveolar type II epithelial cells from diseased mice have a reduced capacity to stimulate naïve and pre-activated self-reactive CD4+ T cells and exhibit broad changes in their gene expression profile in comparison to alveolar type II epithelial cells derived from healthy control mice. Furthermore, alveolar type II epithelial cells from diseased mice secrete soluble factors that down modulate T cell proliferation. Data obtained by extensive functional and molecular characterization suggest an important role of alveolar type II epithelial cells for the induction of T cell tolerance and immune regulation in the lung.Immer mehr Anzeichen deuten darauf hin, dass die Lunge ein Organ mit tolerogenen Eigenschaften ist, um den immunologischen Kollaps, der durch Infektionen und Entzündungen verursacht werden könnte, zu vermeiden. Über die Mechanismen, die zu einer peripheren Toleranzinduktion in der Lunge führen ist allerdings wenig bekannt. Um die immunologischen und molekularen Mechanismen einer autoimmunvermittelten Lungenerkrankung zu untersuchen, wurde die CD4+ T-Zellreaktivität gegenüber des Hämagglutinins (HA) untersucht, welches in den alveolaren Typ II Epithelzellen transgen exprimiert wird. Die gleichzeitige Expression von HA und einem MHC Klasse-II-restringierten T-Zellrezeptor spezifisch für das HA in doppeltransgenen Mäusen führt zu einer schwerwiegenden T-Zellvermittelten interstitiellen Lungenerkrankung. Trotz der schnell fortschreitenden und aggressiven Entzündung der Lungen in jungen Mäusen, stagniert diese in älteren Tieren und lässt auf die Induktion von peripheren Toleranzmechanismen schließen. Intensive immunologische Untersuchungen der selbstreaktiven CD4+ T-Zellen aus den erkrankten Lungen und das Erstellen eines Genexpressionsprofils dieser Zellen ließen den Schluss zu, dass während des Entzündungsprozesses funktionelle, regulatorische T-Zellen induziert werden. Die Etablierung eines neuen Protokolls zur Isolierung reiner und vitaler alveolar Typ II Epithelzellen ex vivo ermöglicht uns die Rolle der Typ II Pneumozyten während der Entzündungsprozesse und Immunregulation zu charakterisieren. Wir zeigen hier, dass alveolare Typ II Epithelzellen aus gesunden Lungen die Fähigkeit haben eine antigenspezifische T-Zellantwort auszulösen, aber im Gegenzug dazu die Typ II Pneumozyten aus den erkrankten Lungen eine verminderte Stimulationsfähigkeit aufweisen und Faktoren sekretieren, die die T-Zellproliferation hemmen können. Weitere vergleichende, molekulare und funktionelle Analysen der alveolaren Typ II Epithelzellen aus gesunden und erkrankten Lungen deuten auf eine wichtige Rolle der alveloar Typ II Epithelzellen bei der Induktion von T-Zelltoleranz und der Immunregulation der Lunge hin

Weltklimapolitik im Kongobecken: neue Chance oder Ökorente für die Eliten?

"Vom 29. März bis 8. April 2009 fanden in Bonn Vorbereitungsverhandlungen für die UN-Weltklimakonferenz im Dezember in Kopenhagen statt. Seit der UN-Klimakonferenz von 2007 in Bali steht der Erhalt der Tropenwälder auf der Tagesordnung der internationalen Klimaverhandlungen. Neben der Reduzierung des CO2-Ausstoßes der Industrieländer wird ein entscheidender Beitrag zur Verminderung des Klimawandels von Ländern erwartet, die über reichhaltige Waldvorkommen verfügen. Damit rücken die Staaten des Kongobeckens in den Mittelpunkt des internationalen Interesses, da sie nach Amazonien über das zweitgrößte tropische Regenwaldgebiet verfügen. Der Bali-Aktionsplan ruft zu Initiativen auf, um Emissionen aus Entwaldung und Walddegradierung zu verringern - bekannt als REDD, Reducing Emissions from Deforestation and Forest Degradation in Developing Countries. Obgleich die REDD-Initiativen für das Kongobecken noch am Anfang stehen, zeichnen sich doch bereits zahlreiche grundlegende Probleme ab: Die bi- und internationalen Geberinitiativen, um den Tropenwaldschutz zu finanzieren und praktisch umsetzen, sind weitgehend unzureichend koordiniert, und zahllose technische Probleme sind noch ungelöst. Bei den Empfängerländern handelt es sich meist um autoritär regierte Staaten, die weder über eine effiziente Verwaltung noch über eine 'gute' Regierungsführung oder eine positive Entwicklungsbilanz verfügen. Dass die zusätzlichen Finanzmittel zum Erhalt des Tropenwaldes als Ökorente von den regierenden Eliten für deren Bereicherung missbraucht werden, ist daher nur schwer auszuschließen. Außerdem sind die Staaten des Kongobeckens für gravierende Menschenrechtsverletzungen bekannt, so dass kaum zu erwarten ist, dass die Bedürfnisse von rund 60 Millionen traditionellen und kleinbäuerlichen Waldnutzern sowie von Waldvölkern berücksichtigt werden, deren nachhaltige Beteiligung als unerlässlich für den Erfolg des Waldschutzes angesehen wird. Durch all diese kaum überschaubaren Schwierigkeiten birgt der mögliche Nutzen der REDD-Initiative zum Schutz des Tropenwaldes erhebliche Risiken." (Autorenreferat