Classification of airborne laser scanning point clouds based on binomial logistic regression analysis

This article presents a newly developed procedure for the classification of airborne laser scanning (ALS) point clouds, based on binomial logistic regression analysis. By using a feature space containing a large number of adaptable geometrical parameters, this new procedure can be applied to point clouds covering different types of topography and variable point densities. Besides, the procedure can be adapted to different user requirements. A binomial logistic model is estimated for all a priori defined classes, using a training set of manually classified points. For each point, a value is calculated defining the probability that this point belongs to a certain class. The class with the highest probability will be used for the final point classification. Besides, the use of statistical methods enables a thorough model evaluation by the implementation of well-founded inference criteria. If necessary, the interpretation of these inference analyses also enables the possible definition of more sub-classes. The use of a large number of geometrical parameters is an important advantage of this procedure in comparison with current classification algorithms. It allows more user modifications for the large variety of types of ALS point clouds, while still achieving comparable classification results. It is indeed possible to evaluate parameters as degrees of freedom and remove or add parameters as a function of the type of study area. The performance of this procedure is successfully demonstrated by classifying two different ALS point sets from an urban and a rural area. Moreover, the potential of the proposed classification procedure is explored for terrestrial data

Community dynamics of bacteria, with special focus on denitrifying bacteria, in a wastewater treatment plant subjected to a new operational mode "controlled disturbances"

Der neue Betriebsmodus “controlled disturbances” wurde für die Abwasserbehandlung in einer Kläranage evaluiert. Seine charakteristischen Merkmale sind eine periodische Variation der den Klärbecken zugeleiteten Abwassermenge, sowie ein periodisches Aussetzen der Belüftung der Nitrifikationsbecken. Der Entwurf des Betriebsmodus zielte darauf ab, durch die Implementierung fluktuierender Umweltbedingungen die Anzahl an ökologischen Nischen für am Klärprozess beteiligte Mikroorganismen und folglich deren Diversität zu erhöhen. Eine Erhöhung der mikrobiellen Diversität sollte mit einer Erhöhung der funktionellen Redundanz der bakteriellen Lebensgemeinschaft einhergehen, wodurch deren funktionelle Stabilität unter ungünstigen Umweltbedingungen verbessert wird. Während seiner Implementierung ermöglichte der Betriebsmodus eine Erhöhung der EBPR- und Denitrifikationsraten, sowie einen niedrigeren Energieverbrauch für die Nitrifikation und eine Erniedrigung des Schlammindex. “Controlled disturbances” stimulierte die denitrifiziernde Aktivität der Bakterien durch die Einführung anaerober Phasen in den Nitrifikationsbecken. Um zu untersuchen, ob die verbesserte Denitrifikationsleistung der Kläranlage auch mit Populationsdynamiken denitrifizierender Bakterien assoziiert war, wurde ein T-RFLP Experiment zur Untersuchung der Diversität der für die Nitrit-Reduktase kodierenden Genen (nirS, nirK) entwickelt. Die Resultate dieser Analyse deuten darauf hin, dass “controlled disturbances” eine Veränderung der Zusammensetzung der Population denitrifizierender Bakterien bewirkt, aber die Anzahl der vorhandenen Arten nicht erhöht hat. Des weiteren konnte ein Effekt auf die Diversität des nirS Gens beobachtet werde, während mögliche Auswirkungen auf die Diversität des nirK Gens uneindeutig waren. Diese unterschiedlichen Trends könnten durch die reduzierte Zugabe von Eisensalzen während “controlled disturbances” bedingt sein und könnten weiters von einer bis dato unerforschten Nischendifferenzierung nirS und nirK besitzender Bakterien herrühren. Der Effekt von “controlled disturbances” auf die Struktur der gesamten bakteriellen Lebensgemeinschaft wurde mittels DGGE Analyse des 16S rRNS Gens untersucht. Die Ergebnisse dieser Experimente legen nahe, dass “controlled disturbances” zur Selektion einer neu strukturierten bakteriellen Lebensgemeinschaft geführt haben, welche die für die Abwasserreinigung nötigen Prozesse unter den neuen Umweltbedingungen effizienter ausgeführt hat, als jene Lebensgemeinschaft, die während der Implementierung des regulären Betriebsmodus anwesend war es unter den damals vorherrschenden Bedingungen tun konnte. Ob diese neue Lebensgemeinschaft nur unterschiedlich strukturiert oder auch diverser war, konnte mit den eingesetzten Methoden nicht mit Sicherheit festgestellt werden. Zur Identifizierung von Bakterien deren Abundanz von “controlled disturbances” beeinflusst wurde, wurden FISH Sonden entworfen, die aus DGGE Banden erhaltene Sequenzen detektieren. Drei dieser Sonden konnten erfolgreich eingesetzt werden. Bei keiner der detektierten Populationen zeigte die Abundanz in Reaktion auf die Implementierung von “controlled disturbances” einen Trend, welcher mit dem der korrespondierenden DGGE Banden vergleichbar gewesen wäre. Dieses Ergebnis legt nahe, dass Schlussfolgerungen über Abundanzveränderungen von Mikroorganismen basierend auf Sequenzen, die aus DGGE Banden gewonnen wurden, nicht ohne zusätzliche experimentelle Bestätigung getroffen werden können, im Speziellen dann wenn die betreffende Bande heterogene DNA beinhaltet hat.A new operational mode termed “controlled disturbances” was evaluated for wastewater treatment. Its characteristic features are periodic changes of wastewater load and periodic shutdown of aeration of nitrification tanks. The operational mode was designed to enhance microbial diversity by introducing fluctuating environmental conditions and thus providing more niches for bacteria. Enhanced microbial diversity should increase the functional redundancy of the bacterial community and thus increase its functional stability when subjected to unfavourable conditions. During its implementation, “controlled disturbances” enabled higher EBPR and denitrification rates as well as lower energy requirements for nitrification and also improved the sludge settling behaviour. “Controlled disturbances” introduced anaerobic phases to nitrification tanks which stimulated the denitrifying activity of bacteria. To investigate whether the improved denitrification performance of the wastewater treatment plant was also linked to community dynamics of denitrifying bacteria, a T-RFLP approach was developed for monitoring of nitrite reductase gene (nirS, nirK) diversity. Results indicated that “controlled disturbances” induced a shift of the community composition of denitrifying bacteria but did not enhance denitrifier species richness. An effect of “controlled disturbances” on nirS diversity was detected whereas effects on nirK diversity were inconclusive. Those different trends were probably caused by a reduced iron salt addition during “controlled disturbances” and could additionally be due to a hitherto unexplored niche differentiation of nirS and nirK possessing bacteria. The effect of “controlled disturbances” on the entire bacterial community structure was investigated by DGGE analysis of 16S rRNA genes. The obtained data suggested that “controlled disturbances” selected for a newly structured bacterial population that was able to exhibit wastewater treatment processes in a more efficient way under the implemented environmental conditions than the community present during normal operation was able to do under the respective environmental conditions. Whether this community was more diverse or just differently structured could not be concluded with certainty. FISH probes targeting sequences obtained from DGGE bands were designed to identify bacteria whose abundance was affected by “controlled disturbances”. Three probes were successfully applied. None of these targeted populations showed a response to the implementation of “controlled disturbances” comparable to the DGGE bands they corresponded to. This finding suggests that it is problematic to draw conclusions about the occurrence of organisms in environmental samples based on sequence data obtained from DGGE bands, especially if bands contain heterogeneous DNA

Shaping the world : why do female students graduate more often than male students in OECD member states?

Across OECD countries, girls and young women often outperform their peers in educational attainment, and in testing achievements in almost all educational levels. This bachelor thesis investigates driving forces behind the phenomenon including variation between OECD member states and field of study. Since the issue of gender equality has arisen, the phenomenon of gender gaps in general has become increasingly relevant. Gender gaps in education and income are strong indicators for equality in a country’s society, which in turn delivers greater growth and inclusiveness. Although there are already several empirical studies about the growing gender gap in education in OECD member states as well as in other countries around the globe, it has been little empirical research done about the driving forces behind the phenomenon. The findings of this current thesis are in line with the few existing approaches. Mostly external, societal and economic factors were found to be driving forces behind the reversal of the gender gap in education and any variation across OECD countries. Whereas the interaction of external and internal factors explains why there is any female educational advantage possible at all. Against all odds, performance was not found to be responsible for gender variation in the field of study, rather motivation accounts for a bulk of gender differences in certain specialties

Imperialist appropriation in the world economy: drain from the global South through unequal exchange, 1990–2015

Unequal exchange theory posits that economic growth in the “advanced economies” of the global North relies on a large net appropriation of resources and labour from the global South, extracted through price differentials in international trade. Past attempts to estimate the scale and value of this drain have faced a number of conceptual and empirical limitations, and have been unable to capture the upstream resources and labour embodied in traded goods. Here we use environmental input-output data and footprint analysis to quantify the physical scale of net appropriation from the South in terms of embodied resources and labour over the period 1990 to 2015. We then represent the value of appropriated resources in terms of prevailing market prices. Our results show that in 2015 the North net appropriated from the South 12 billion tons of embodied raw material equivalents, 822 million hectares of embodied land, 21 exajoules of embodied energy, and 188 million person-years of embodied labour, worth $10.8 trillion in Northern prices – enough to end extreme poverty 70 times over. Over the whole period, drain from the South totalled$242 trillion (constant 2010 USD). This drain represents a significant windfall for the global North, equivalent to a quarter of Northern GDP. For comparison, we also report drain in global average prices. Using this method, we find that the South's losses due to unequal exchange outstrip their total aid receipts over the period by a factor of 30. Our analysis confirms that unequal exchange is a significant driver of global inequality, uneven development, and ecological breakdown

Characterization of cellular membranes under conditions of ether lipid deficiency

Etherlipide bilden eine Klasse von Lipiden, die sich durch ihre O-Alkyl-Bindung an der sn-1-Position ihres Glycerin-Rückgrats auszeichnen und deren erste Biosyntheseschritte im Peroxisom ablaufen. Plasmalogene, die wichtigsten Etherlipide, haben große physiologische Bedeutung, zum Beispiel als strukturgebende Moleküle in der Zellmembran. Ein Mangel an Etherlipiden führt im Menschen zu einer schweren Krankheit, rhizomelischer Chondrodysplasia punctata. Neueste Forschungsarbeiten zeigten, dass auch eine Untergruppe der GPI-Anker, einer posttranslationalen Modifikation, die Proteine an der Außenseite der Zellmembran verankert, eine Etherbindung beinhaltet und damit vom peroxisomalen Biosyntheseweg abhängig ist. GPI-verankerte Proteine werden innerhalb der Membran in kleine Subdomänen, „membrane rafts“, dirigiert. Mittels Nano-Elektrospray-Ionisierungs-Massenspektrometrie kann gezeigt werden, dass das Fehlen der Plasmalogene durch die erhöhte Synthese anderer Phospholipide, der Phosphatidylethanolamine, die die gleiche Kopfgruppe (Ethanolamin) wie die meisten Plasmalogene besitzen, kompensiert wird. In Zellkultur kann der Defekt in der peroxisomalen Etherlipid-Biosynthese umgangen werden, indem Vorläufermoleküle mit bereits vorhandener Etherbindung dem Medium beigemengt werden. Interessanterweise reagieren Fibroblasten auf die vermehrte Bildung von Plasmalogenen bei Verfügbarkeit einer solchen Substanz mit einer Reduktion von Phosphatidylethanolaminen. Das weist darauf hin, dass die insgesamte Menge an Ethanolamin-Phospholipiden konstant gehalten wird. Weiters wird bewiesen, dass eine O-Alkyl-Kette in GPI-Ankern nicht zwingend für deren Membranassoziation erforderlich ist. Hingegen zeigt sich, dass die Menge an einzelnen Raft-Proteinen, auch GPI-verankerten Proteinen, in Etherlipid-defizienten Zellen verändert ist. Die Rafts weisen zusätzlich ein verändertes Flotationsverhalten in einem Saccharose-Dichtegradienten auf. Als mögliche funktionelle Konsequenz dieser Veränderungen können leicht verkleinerte Acetylcholinrezeptor-Cluster bei der Enstehung der neuromuskulären Synapse in vitro an Hand von Myotuben aus Etherlipid-defizienten Mäusen, nachgewiesen werden.Ether lipids form a specialized class of lipids that are characterized by an O-alkyl bond at the sn-1 position of their glycerol backbone. The initial steps of their biosynthesis take place in the peroxisome. Among ether lipids, plasmalogens take on a dominant role. They perform important physiological functions, for example as constituents of cellular membranes. In humans, the lack of ether lipids causes a fatal disease, rhizomelic chondrodysplasia punctata. Research has also identified a subpopulation of glycosylphosphatidylinositol anchors, a posttranslational modification that targets proteins to the outer surface of the cell membrane, as an ether lipid. Proteins associated with the membrane by GPI anchorage are recruited to specialized domains called membrane rafts, which are also enriched in plasmalogens. These microdomains constitute important platforms for various cellular processes e.g. signal transduction. Nano-electrospray ionization mass spectrometric analysis of these primary cultured human fibroblasts shows that the cells compensate for the loss of plasmalogens by increasing the synthesis of other phospholipids, namely phosphatidylethanolamines, which share the head group (ethanolamine) with the majority of plasmalogens. Supplementation of ether lipid-deficient cultures with plasmalogen precursors that already contain an ether linkage circumvents the peroxisomal steps of ether lipid synthesis. Interestingly, the resulting rescue of plasmalogen levels causes a corresponding decline in phosphatidylethanolamines, so that the amount of total ethanolamine phospholipids is kept constant in every circumstance. In addition, the present study offers the proof that an O-alkyl chain is not necessarily required for the membrane anchoring of Thy-1, a GPI-anchored protein. However, sucrose density gradient centrifugation suggests a reorganization of membrane rafts upon depletion of ether lipids. Furthermore, some raft proteins, amongst others GPI-anchored proteins, exhibit changed amounts in western blot analysis and show an altered floating behavior in a density gradient. Additionally, preliminary experiments in murine myoblast cultures derived from ether lipid-deficient mice point to differences in the formation of the neuromuscular junction under conditions of ether lipid deficiency. Summarizing, in spite of compensatory mechanisms employed by human fibroblasts in response to ether lipid deficiency, a variety of changes, especially concerning cellular membranes, can be detected under these conditions