Machine learning with screens for detecting bid-rigging cartels

We combine machine learning techniques with statistical screens computed from the distribution of bids in tenders within the Swiss construction sector to predict collusion through bid-rigging cartels. We assess the out of sample performance of this approach and find it to correctly classify more than 80% of the total of bidding processes as collusive or non-collusive. As the correct classification rate, however, differs across truly non-collusive and collusive processes, we also investigate tradeoffs in reducing false positive vs. false negative predictions. Finally, we discuss policy implications of our method for competition agencies aiming at detecting bid- rigging cartel

An alternative insert of three amino acids is incorporated into collagen XIV in a developmentally regulated fashion1The novel nucleotide sequences reported in this paper have been submitted to the GenBank/EMBL database with accession number AJ011841.1

AbstractWe have identified a novel splice variant of chicken collagen XIV which contains an insert of three amino acids (Val-Arg-Thr) in the sixth fibronectin type III-like (FNIII) domain. The codons for these amino acids are inserted into the mRNA by skipping of a splice donor site and usage of another donor site 9 bp further downstream in the collagen XIV gene. The percentage of the new splice variant in the total collagen XIV mRNA varies between 22 and 46% in different embryonic tissues. After hatching, however, this percentage increases dramatically and reaches 86% in adult skeletal muscle and 58% in adult gizzard, indicating developmental regulation of this splicing event. Computer modeling suggests that the three extra amino acids cause an increase in the size of a flexible loop connecting two β-strands in the sixth FNIII domain. This increase might affect the exact arrangement of the FNIII domain in the collagen XIV molecule, thereby modulating its interactions with other matrix molecules

Polarisationsdatenspeicherung in Bakteriorhodopsin-Schichten

Die Weitergabe von Wissen, Regeln und Gesetzen in Form von gespeicherten Informationen hat mit einfachen Steintafeln begonnen und sich über Papyrusrollen, dem Buchdruck bis hin zur Verwendung von Computern zur Datenspeicherung entwickelt. Magnetische Festplatten kommen heute bis auf einige Terabits Speichervolumen. Die optische Informationsspeicherung in Form von CDs (Compact Discs) und DVDs (Digital Verstile Discs) ist weit verbreitet. Die Nummer der Pits and Lands ist limitiert und eine normale CD erlaubt eine Speicherung von bis zu 700 MB. Durch kleinere Laserspots, anderen Wellenlängen zum Auslesen und engere Beschreibung der Datendiscs wurde bei Blue Rays das Datenvolumen bis auf 50 GB erweitert. Auf diesem Wege sind die Grenzen der Datenspeicherung noch nicht ausgereizt. Die optische Datenspeicherung lässt sich in fünf Dimensionen ausweiten, dazu gehören neben der Ortsauflösung in XYZ-Richtung des Speichermediums noch die Auslesewellenlänge für verschiedene Farbstoffe sowie die Polarisationsrichtung des Lichts. Optische Datenspeicherung ist auch mit Bakteriorhodopsin (BR) möglich. Seit der Erforschung des BR in den 70ern wurden bis heute verschiedene technische Anwendungen des Biomoleküles diskutiert. So sind photochrome Sicherheitstinten, die den Protonpumpmechanismus des Proteins nutzen, von Interesse. Ein anderes großes Potential ist die Polarisationsdatenspeicherung. Das Ziel dieser Dissertation ist es, die Veränderungen aufzuzeigen, die bei der Polarisationsdatenspeicherung eintreten, beginnend im molekularen bis hin zum makroskopisch messbaren Effekt. Der für die Datenspeicherung von Fischer und Mastay postulierte Zustand P360 wurde bereits früher schon UV-Vis spektroskopisch untersucht. In dieser Arbeit werden mit CD-Spektroskopie, AFM und SAXS strukturelle Veränderungen auf der mikroskopischen Ebene diesen Zustand nach Bestrahlung mittels Pulslaser aufklären. Ergänzt durch massenspektrometrische Messungen kann die Ursache der Irreversibilität des Schreibvorgangs aufgeklärt werden. Im zweiten Teil werden die externen Einflüsse auf das Datenspeichern aufgezeigt. Der makroskopisch messbare Effekt des Datenspeicherns wird mittels Polarimetrie untersucht. Mit einer mathematischen Beschreibung durch den Stokes-Formalismus wird der Effekt der Polarisationsdatenspeicherung beschrieben. Die Speicherkapazität eines Polarisationsdatenspeichers übersteigt herkömmliche Datenspeicher um ein vielfaches

A field guide to Berlin. Designing teaching material for a field visit in urban studies

This field guide is part of a larger field course called ‘Urban Dynamics’ (Dynamiques Urbaines), running in the third year of the Bachelor degree in Geography at the University of Lausanne. In this course, students are expected to define and realise for the first time a self-organised research project in groups, taking place in Berlin. It starts from the observation that urban change is always subject to contestation and debate, and therefore to politics. We distinguish between big P Politics, that is, the institutionalised politics of political institutions, state actors, and officials; and small p politics, the politics of everyday contestations, solidarity, protesting and sometimes of simply acting in one way than another, that pervades Berlin. It contains two field days in Berlin that students can undertake as a self-guided tour. Each day has four sites for which the field guide contains both background information, key concepts of urban geography, and questions that familiarise them with important debates

Blockade but not overexpression of the junctional adhesion molecule C influences virus-induced type 1 diabetes in mice

Type 1 diabetes (T1D) results from the autoimmune destruction of insulin-producing beta-cells in the pancreas. Recruitment of inflammatory cells is prerequisite to beta-cell-injury. The junctional adhesion molecule (JAM) family proteins JAM-B and JAM–C are involved in polarized leukocyte transendothelial migration and are expressed by vascular endothelial cells of peripheral tissue and high endothelial venules in lympoid organs. Blocking of JAM-C efficiently attenuated cerulean-induced pancreatitis, rheumatoid arthritis or inflammation induced by ischemia and reperfusion in mice. In order to investigate the influence of JAM-C on trafficking and transmigration of antigen-specific, autoaggressive T-cells, we used transgenic mice that express a protein of the lymphocytic choriomeningitis virus (LCMV) as a target autoantigen in the β-cells of the islets of Langerhans under the rat insulin promoter (RIP). Such RIP-LCMV mice turn diabetic after infection with LCMV. We found that upon LCMV-infection JAM-C protein was upregulated around the islets in RIP-LCMV mice. JAM-C expression correlated with islet infiltration and functional beta-cell impairment. Blockade with a neutralizing anti-JAM-C antibody reduced the T1D incidence. However, JAM-C overexpression on endothelial cells did not accelerate diabetes in the RIP-LCMV model. In summary, our data suggest that JAM-C might be involved in the final steps of trafficking and transmigration of antigen-specific autoaggressive T-cells to the islets of Langerhans

Strategy abundance in 2x2 games for arbitrary mutation rates

We study evolutionary game dynamics in a well-mixed populations of finite size, N. A well-mixed population means that any two individuals are equally likely to interact. In particular we consider the average abundances of two strategies, A and B, under mutation and selection. The game dynamical interaction between the two strategies is given by the 2x2 payoff matrix [(a,b), (c,d)]. It has previously been shown that A is more abundant than B, if (N-2)a+Nb>Nc+(N-2)d. This result has been derived for particular stochastic processes that operate either in the limit of asymptotically small mutation rates or in the limit of weak selection. Here we show that this result holds in fact for a wide class of stochastic birth-death processes for arbitrary mutation rate and for any intensity of selection.Comment: version 2 is the final published version that contains minor changes in response to referee comment

The ribosome receptors Mrx15 and Mba1 jointly organize cotranslational insertion and protein biogenesis in mitochondria

Mitochondrial gene expression in Saccharomyces cerevisiae is responsible for the production of highly hydrophobic subunits of the oxidative phosphorylation system. Membrane insertion occurs cotranslationally on membrane-bound mitochondrial ribosomes. Here, by employing a systematic mass spectrometry-based approach, we discovered the previously uncharacterized membrane protein Mrx15 that interacts via a soluble C-terminal domain with the large ribosomal subunit. Mrx15 contacts mitochondrial translation products during their synthesis and plays, together with the ribosome receptor Mba1, an overlapping role in cotranslational protein insertion. Taken together, our data reveal how these ribosome receptors organize membrane protein biogenesis in mitochondria