Simple biophysics underpins collective conformations of the intrinsically disordered proteins of the Nuclear Pore Complex

Nuclear Pore Complexes (NPCs) are key cellular transporter that control nucleocytoplasmic transport in eukaryotic cells, but its transport mechanism is still not understood. The centerpiece of NPC transport is the assembly of intrinsically disordered polypeptides, known as FG nucleoporins, lining its passageway. Their conformations and collective dynamics during transport are difficult to assess in vivo. In vitro investigations provide partially conflicting results, lending support to different models of transport, which invoke various conformational transitions of the FG nucleoporins induced by the cargo-carrying transport proteins. We show that the spatial organization of FG nucleoporin assemblies with the transport proteins can be understood within a first principles biophysical model with a minimal number of key physical variables, such as the average protein interaction strengths and spatial densities. These results address some of the outstanding controversies and suggest how molecularly divergent NPCs in different species can perform essentially the same function

Rule learning enhances structural plasticity of long-range axons in frontal cortex.

Rules encompass cue-action-outcome associations used to guide decisions and strategies in a specific context. Subregions of the frontal cortex including the orbitofrontal cortex (OFC) and dorsomedial prefrontal cortex (dmPFC) are implicated in rule learning, although changes in structural connectivity underlying rule learning are poorly understood. We imaged OFC axonal projections to dmPFC during training in a multiple choice foraging task and used a reinforcement learning model to quantify explore-exploit strategy use and prediction error magnitude. Here we show that rule training, but not experience of reward alone, enhances OFC bouton plasticity. Baseline bouton density and gains during training correlate with rule exploitation, while bouton loss correlates with exploration and scales with the magnitude of experienced prediction errors. We conclude that rule learning sculpts frontal cortex interconnectivity and adjusts a thermostat for the explore-exploit balance

On the Stability of Research Joint Ventures: Implications for Collusion

Though there is a body of theoretical literature on research joint ventures (RJV) participation facilitating collusion, empirical tests are rare. Even more so, there are few empirical tests on the general theme of collusion. This note tries to fill this gap by assuming a correspondence between the stability of research joint ventures and collusion. By using data from the US Nation Cooperation Research Act, we show that large RJVs in concentrated industries are more stable and hence more suspect to collusion

Shaker slip-plate adapter

Magnesium adapter ties in all of the attachment bosses on a horizontal slip table and makes a rigid coupling which terminates in a single row of attachment bosses at the edge of the horizontal plate. This eliminates ineffective dissipation of the driving force in vibration tests

On the Stability of Research Joint Ventures: Implications for Collusion

Though there is a body of theoretical literature on research joint ventures (RJV) participation facilitating collusion, empirical tests are rare. Even more so, there are few empirical tests on the general theme of collusion. This note tries to fill this gap by assuming a correspondence between the stability of research joint ventures and collusion. By using data from the US Nation Cooperation Research Act, we show that large RJVs in concentrated industries are more stable and hence more suspect to collusion.research joint ventures; product market collusion; empirical test

The Dynamics of Research Joint Ventures: A Panel Data Analysis

The aim of this paper is to test the determinants of Research Joint Ventures’ (RJVs) group dynamics. We look at entry, exit and turbulence in RJVs that have been set up under the US National Cooperative Research Act, which allows for certain antitrust exemptions in order to stimulate firms to cooperate in R&D. Accounting for unobserved project characteristics and controlling for inter-RJV interactions and industry effects, the Tobit panel regressions show the importance of group and time features for an RJV’s evolution. We further identify an average RJV’s long-term equilibrium size and assess its determining factors. Ours is a first attempt to produce robust stylized facts about cooperational short- and long-term dynamics, an important but neglected dimension in research cooperations

On the Desirability of an Efficiency Defense in Merger Control

We develop a model in which two firms that have proposed to merge are privately informed about merger-specific efficiencies. This enables the firms to influence the merger control procedure by strategically revealing their information to an antitrust authority. Although the information improves upon the quality of the authority's decision, the influence activities may be detrimental to welfare if information processing/gathering is excessively costly. Whether this is the case depends on the merger control institution and, in particular, whether it involves an efficiency defense. We derive the optimal institution and provide conditions under which an efficiency defense is desirable. We also discuss the implications for antitrust policy and outline a three-step procedure that take the influence activities into consideration. ZUSAMMENFASSUNG - (Wann ist eine Effizienzverteidigung in der Fusionskontrolle wünschenswert?) Eine Effizienzverteidigung in der Fusionskontrolle besagt, dass wettbewerbsbeschränkende Fusionen dann erlaubt werden, wenn hinreichend große Synergieeffekte zu erwarten sind. Mögliche Synergieeffekte einer Fusion sind jedoch hauptsächlich den fusionierenden Unternehmen bekannt. Eine Effizienzverteidigung ermöglicht es den fusionierenden Unternehmen, die Entscheidung der Wettbewerbsbehörde zu beeinflussen, indem sie der Wettbewerbsbehörde ihre Informationen strategisch weitergeben (oder zurückhalten). Die Autoren untersuchen, ob und wann eine Effizienzverteidigung aus gesellschaftlicher Sicht wünschenswert ist. Hierzu entwickeln sie ein Model, in dem Unternehmen, die fusionieren möchten, private Informationen über die Synergieeffekte der Fusion besitzen. Die Unternehmen können die Entscheidung der Wettbewerbsbehörde beeinflussen, indem sie ihre Informationen strategisch an die Wettbewerbsbehörde weiterleiten. Obwohl die Informationen über Synergien die Entscheidung der Wettbewerbsbehörde verbessern, kann die Einflussnahme der Firmen die Wohlfahrt verringern, falls die Firmen zu viel in das Sammeln und Verarbeiten dieser Informationen investieren. Ob dies der Fall ist, hängt von der Ausgestaltung der Fusionskontrolle ab und insbesondere davon, ob die Fusionskontrolle eine Effizienzverteidigung zulässt. In dem theoretischen Model wird die optimale Fusionskontrollinstitution hergeleitet und Bedingungen herausgearbeitet unter denen eine Effizienzverteidigung wünschenswert ist. Die Autoren erörtern die Implikationen des Modells für die Fusionspolitik und entwickeln ein Drei-Stufen-Verfahren für Fusionsentscheidungen, welches die Einflussaktivitäten der Unternehmen berücksichtigt.Lobbying, Rent Seeking, Asymmetric Information, Disclosure, Efficiency Gains, Antitrust

Inequality and attitudes: postcommunism, western capitalism and beyond

This paper* deals with attitudes towards inequality in cross-national perspective using survey data of the International Social Survey Programme (ISSP) of 1992. Factor analysis shows that perceptions and evaluations of inequality and stratification refer to four attitudinal dimensions: Egalitarianism, meritocratic beliefs, functionalist convictions and the perception of non-universalistic status ascription. With these dimensions one gets an impression of the patterns of attitudes held in different countries. The main differences between post-communist and western capitalist countries concern egalitarian attitudes: East Europeans are much more egalitarian. This applies especially to the role of the state. Concerning the other three dimensions, other variables explain international variation in attitudes better than the belonging to the East or the West. Nevertheless, over the whole range of questions there is a visible separation between post-communist and western capitalist countries - but not into two „blocs“, but into a number of „families of nations“. Cluster analysis brings together societies that are similar in terms of social history as well as in terms of geography and welfare institutions. --

The Dynamics of Research Joint Ventures: A Panel Data Analysis

The aim of this paper is to test the determinants of Research Joint Ventures’ (RJVs) group dynamics. We look at entry, exit and turbulence in RJVs that have been set up under the US National Cooperative Research Act, which allows for certain antitrust exemptions in order to stimulate firms to cooperate in R&D. Accounting for unobserved project characteristics and controlling for inter-RJV interactions and industry effects, the Tobit panel regressions show the importance of group and time features for an RJV’s evolution. We further identify an average RJV’s long-term equilibrium size and assess its determining factors. Ours is a first attempt to produce robust stylized facts about cooperational short- and long-term dynamics, an important but neglected dimension in research cooperations.research joint ventures; dynamics; panel data

Estimating Markups under Nonlinear Pricing Competition

This paper provides a structural interpretation to the estimates of the shape and position of nonlinear tariffs. We focus on the evaluation of price-cost margins, and thus we need to identify marginal cost from an equilibrium model of nonlinear pricing competition. We estimate these price-cost margins using quarterly data from the early U.S. cellular telephone industry between 1984 and 1988. Our results indicate that the margins are increased under duopoly, due to a significant reduction in marginal costs. Moreover, we find that the price-cost margins vary over the consumption levels and that low end users are subject to higher price-cost margins than high-end users. The impact of competition further increases the margins in the low-end user segment, relative to high endusers. In that sense the benefits of competition, which are largely due to increased efficiencies, are passed on relatively more to high-end users. We also show that these findings are robust even if one includes a number of observable market demand and cost variables. ZUSAMMENFASSUNG - (Schätzung von Preisaufschlägen im nicht-linearen Preissetzungswettbewerb) Dieses Papier bietet eine strukturelle Interpretation der Schätzungen der Form und Position nichtlinearer Tarife. Dabei konzentrieren wir uns auf die Bewertung von Preisaufschlägen und müssen daher zunächst die Grenzkosten in einem Gleichgewichtsmodell nicht-linearen Preiswettbewerbs identifizieren. Wir schätzen diese Preisaufschläge, indem wir Quartalsdaten der jungen Mobilfunkindustrie der U.S.A. zwischen 1984 und 1988 verwenden. Die Ergebnisse deuten darauf hin, dass die Aufschläge in einem Duopol aufgrund signifikanter Grenzkostenreduktion größer sind. Außerdem lässt sich feststellen, dass die Preisaufschläge über die Konsumniveaus variieren und dass Nutzer im Niedrigsegment ('low-end') höhere Preisaufschläge zu tragen haben als 'highend'- Nutzer. Der Einfluß des Wettbewerbs vergrößert noch die Preisaufschläge im 'low-end'-Bereich im Vergleich zum 'high-end'. In diesem Sinne profitieren die 'high-end'-Nutzer mehr vom Wettbewerb, der sich vor allem in gesteigerten Effizienzen positiv niederschlägt. Diese Ergebnisse sind robust, wie gezeigt werden kann, sogar wenn eine Reihe beobachtbarer Marktnachfrage- und Kostenvariablen hinzugefügt wird.Estimation of Equilibrium Oligopoly Models, Competitive Nonlinear Pricing, Common Agency