Free University of Berlin

About: Free University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Context (language use). The organization has 35195 authors who have published 66525 publications receiving 2094403 citations. The organization is also known as: FU Berlin.

Innovations and the role of complementarities in a strategic theory of the firm

Abstract: In the resource-based view of strategy and in evolutionary economics, complementary assets play a crucial role in explaining sustainable competitive advantages and innovations. Despite the apparent importance of complementary assets for the understanding of corporate strategy, their creation and the associated managerial problems have been much less discussed. We believe this to be a major weakness in the strategic theory of the firm. Interestingly, problems of coordination and cooperation are center stage in the contract-based theories of the firm, and we try to integrate some of their insights into a resource-based perspective. Specifically, we show how complementary assets raise the need for strategic direction by a firm's top management. Moreover, complementary assets magnify internal incentive problems, and their management has an impact on the innovativeness of a firm. Lastly, complementary assets play a crucial role in the internal appropriation of innovative rents. We demonstrate the fruitfulness of our integrated framework by relating some of our findings to the literature on corporate strategy, industry evolution, and organizational structures. Copyright © 2007 John Wiley & Sons, Ltd.

Transferrin receptor 1 is a cellular receptor for New World haemorrhagic fever arenaviruses

Abstract: The transferrin receptor 1 (TfR1) has been identified as the cellular receptor for four New World arenaviruses — the Junin, Machupo, Guanarito and Sabia viruses. This class of arenaviruses is important because they cause fatal haemorrhagic fevers. Treating cultured cells with an antibody against TfR1 blocks viral entry and replication. Antibodies that limit arenavirus replication without interfering with host iron metabolism may be effective in controlling outbreaks of New World haemorrhagic fever. At least five arenaviruses cause viral haemorrhagic fevers in humans. Lassa virus, an Old World arenavirus, uses the cellular receptor α-dystroglycan to infect cells1. Machupo, Guanarito, Junin and Sabia viruses are New World haemorrhagic fever viruses that do not use α-dystroglycan2. Here we show a specific, high-affinity association between transferrin receptor 1 (TfR1) and the entry glycoprotein (GP) of Machupo virus. Expression of human TfR1, but not human transferrin receptor 2, in hamster cell lines markedly enhanced the infection of viruses pseudotyped with the GP of Machupo, Guanarito and Junin viruses, but not with those of Lassa or lymphocytic choriomeningitis viruses. An anti-TfR1 antibody efficiently inhibited the replication of Machupo, Guanarito, Junin and Sabia viruses, but not that of Lassa virus. Iron depletion of culture medium enhanced, and iron supplementation decreased, the efficiency of infection by Junin and Machupo but not Lassa pseudoviruses. These data indicate that TfR1 is a cellular receptor for New World haemorrhagic fever arenaviruses.

The evolutionary adaptation of flower colours and the insect pollinators' colour vision

Abstract: The evolutionary tuning between floral colouration and the colour vision of flower-visiting Hymenoptera is quantified by evaluating the informational transfer from the signalling flower to the perceiving pollinator. The analysis of 180 spectral reflection spectra of angiosperm blossoms reveals that sharp steps occur precisely at those wavelengths where the pollinators are most sensitive to spectral differences. Straight-forward model calculations determine the optimal set of 3 spectral photoreceptor types for discrimination of floral colour signals on the basis of perceptual difference values. The results show good agreement with the sets of photoreceptors characterized electrophysiologically in 40 species of Hymenoptera.