Functional studies on oligotropha carboxidovorans molybdenum–copper CO dehydrogenase produced in escherichia coli

The Mo/Cu-dependent CO dehydrogenase (CODH) from Oligotropha carboxidovorans is an enzyme that is able to catalyze both the oxidation of CO to CO2 and the oxidation of H2 to protons and electrons. Despite the close to atomic resolution structure (1.1 Å), significant uncertainties have remained with regard to the reaction mechanism of substrate oxidation at the unique Mo/Cu center, as well as the nature of intermediates formed during the catalytic cycle. So far, the investigation of the role of amino acids at the active site was hampered by the lack of a suitable expression system that allowed for detailed site-directed mutagenesis studies at the active site. Here, we report on the establishment of a functional heterologous expression system of O. carboxidovorans CODH in Escherichia coli. We characterize the purified enzyme in detail by a combination of kinetic and spectroscopic studies and show that it was purified in a form with characteristics comparable to those of the native enzyme purified from O. carboxidovorans. With this expression system in hand, we were for the first time able to generate active-site variants of this enzyme. Our work presents the basis for more detailed studies of the reaction mechanism for CO and H2 oxidation of Mo/Cu-dependent CODHs in the future

Bayesian estimation of sparse dynamic factor models with order-independent identification

The analysis of large panel data sets (with N variables) involves methods of dimension reduction and optimal information extraction. Dimension reduction is usually achieved by extracting the common variation in the data into few factors (k, where k << N). In the present project, factors are estimated within a state space framework. To obtain a parsimonious representation, the N x k factor loading matrix is estimated under a sparse prior, which assumes that either many zeros may be present in each column of the matrix, or many rows may contain zeros. The significant factor loadings in columns define the variables driven by specific factors and offer an explicit interpretation of the factors. Zeros in rows indicate irrelevant variables which do not add much information to the inference. The contribution includes a new way of identification which is independent of variable ordering and which is based on semi-orthogonal loadings

Investors care about risk, but can't cope with volatility

Following the classical portfolio theory all an investor has to do for an optimal investment is to determine his risk attitude. This allows him to find his point on the capital market line by combining a risk-free asset with the market portfolio. We investigate the following research questions in an experimental set-up: Do private investors see a relationship between risk attitude and the amount invested risky at all and do they adjust their investments if provided with different risk levels of the risky asset? To answer these questions we ask subjects in a between subject design to allocate a certain amount between a risky and a risk-free asset. Risky assets differ between conditions, but can be transformed into each other by combining them with the risk-free asset. We find that mainly investors risk attitude, but also their risk perception, and the investment horizon are strong predictors for risk taking. Indeed, investors do not appear to be naïve, but they do something sensitive. Nevertheless, we observe a strong framing effect: investors choose almost the same allocation to the risky asset independently of changes in its risk-return profile thus ending up with significantly different volatilities. Feedback does not mitigate the framing effect. The effect is somewhat smaller for investors with a high financial literacy. Overall, people seem to use two mental accounts, one for the risk-free and one for the risky investment with the risk attitude determining the percentage allocation to the risky asset and not the chosen portfolio volatility

Does the materiality of museum collections matter in Digital Humanities?

After more than one hundred years of increasingly self-reflective collecting, museums and archives around the globe hold an immense corpus of physical objects and relevant archival material from the Sepik area of Papua New Guinea. While culturally coded knowledge is embodied in these materials, the use of additional outside observations may help to describe some of these areas of knowledge. To keep traditional knowledge alive, methodologies beyond the reading of traditional texts, photographs, and sound recordings have to be developed and applied consistently. The unusual complexity and high diversity of Sepik art makes developing new digital methods of storing, studying, and sharing these resources a challenging task. Future museum activities are likely to put the original object into a new, focused light. Long overlooked aspects in the work of artists may thus come to the fore. By communicating with source communities and, at the end other end, with museum visitors, and by fostering research activities combining the context oriented approach of disciplines rooted in natural science and/or in the humanities, museums will redefine our views of Sepik art and culture.Après plus d’un siècle de réflexivité croissante sur leurs pratiques de collecte, les musées et les archives, à travers le monde, détiennent un corpus immense d’objets mais aussi de matériel documentaire liés à la région du Sepik. Alors que ces sources conservent tout un savoir culturel obéissant aux codes culturels locaux, des observations extérieures aideront à identifier certains domaines de ce savoir. Afin de conserver vivant le savoir traditionnel, une même méthodologie doit être développée et appliquée systématiquement. La complexité inhabituelle des objets d’art du Sepik requiert la mise en place de nouvelles méthodes numériques d’archivage. Dans le futur, les activités des musées associeront aux objets une connaissance plus précise et certains aspects du travail des artistes y gagneront une place centrale. En communiquant avec les communautés locales mais aussi avec les visiteurs des musées, en encourageant à l’approche contextuelle propres aux sciences naturelles ainsi qu’aux humanités, les musées redéfiniront notre vision de l’art et de la culture du Sepik

Development and optimization of a biotechnological process for the production of butanol with Clostridium saccharoperbutylacetonicum

n-Butanol sowie seine Ester und Ether werden vorwiegend in der chemischen Industrie in Farben, Lacken und Klebern eingesetzt. Außerdem wird es als Zusatz in Kraftstoffen diskutiert. Für eine kostengünstige biotechnische Produktion ist es jedoch notwendig die schon seit langem bestehenden Probleme im strikt anaeroben Prozess zu lösen oder zu umgehen. Dazu gehören die geringe Butanolkonzentration in Kultur (15-21 g/L) sowie die schlechte Abtrennbarkeit des toxischen Produktes aus der Fermentationsbrühe. Außerdem ist ein solcher Prozess nur rentabel, wenn alternative Substrate eingesetzt werden, die nicht mit Nahrungsmitteln konkurrieren. In dieser Arbeit wurden Agrarsubstrate wie Zuckerrübe und lignocellulosehaltiges, hydrolysiertes Weizenkaff erfolgreich zu Butanol und Aceton umgesetzt. Es wurde außerdem mit 2-Butyoctan-1-ol ein geeignetes Extraktionsmittel mit einem Verteilungskoeffizienten von 5 für die in situ-Abtrennung von Butanol aus der Fermentationsbrühe gefunden und erfolgreich eingesetzt.n-butanol as well as his esters and ethers were predominantly used in the chemical industry for colors, lacquers and adhesives. It will also be discussed as a compound in fuels. For an economic biotechnological production it is necessary to overcome long standing existing problems of the strict anaerobic process. These are the low butanol concentration in culture (15-21 g/L) and the difficult separation of the toxic product from the fermentation broth. Additionally such processes are only profitable by using alternative substrates without competition to foods. In this thesis agricultural substrates like sugar beet and lignocellulose containing hydrolyzed wheat chaff was successfully converted to butanol and acetone. With 2-butyloctan-1-ol a suitable extractant with a partition coefficient of 5 was found and successfully used for the in situ recovery of butanol from the fermentation broth

The mother and her ancestral face. A commentary on Iatmul iconography

Visually effective symbolization in Iatmul society is reviewed, starting from observations by Bernard Juillerat on the role of the mother in real as well as in symbolic relationships. Ceremonial acts of women and men in the context of naven rituals, and iconological representation anchored in initiatory knowledge are shown to be linked. Performing renders knowledge, services, material objects such as valuables or masks, i.e. cultural entities with a symbolic value, openly accessible for all parties concerned. They become the issue of exchange at specific occasions, enhancing the gendered roles of mother or elder sibling and their complementing actors, child or younger sibling.L’expression visuelle des valeurs symboliques dans la société iatmul est reconsidérée en partant d’observations de Bernard Juillerat sur le rôle de la mère. Sont mis en évidence les  liens entre la façon d’agir, les rôles réels et symboliques de mère, oncle maternel et neveu, aîné et cadet, à travers les rituels naven et les représentations ancestrales matérialisées par des œuvres fondées dans le savoir initiatique des hommes. Les rites publics rendent accessibles à tous les savoir-faire, les prestations ainsi que des objets spécifiques y compris des masques, c’est-à-dire des entités culturelles à valeur symbolique. Leur présentation généralise l’importance des acteurs et de leurs partenaires complémentaires

Das Töpferhandwerk der Kwoma in Nord-Neuguinea : Beiträge zur Systematik primärer Töpfereiverfahren

Töpferei Ethnologie Papua Neu Guinea Fremde Lände