The Spatial Dimension of Knowledge Spillovers in Europe: Evidence from Firm Patenting Data

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Radical versus Non-Radical Inventions

This paper looks at the special characteristics of radical inventions. It tries to identify those variables that differentiate radical inventions from non-radical inventions. Since radical inventions are very important for the economy as a whole and for the individual firm performances, understanding what makes radical inventions differ from non-radical inventions is very important. For our research we made use of the EPO (European Patent Office) database on patents. We used the number of forward patent citations per patent to identify radical from non-radical inventions. For our analysis we used the backward patent citations per patent. In order to test if the two groups we are considering are truly different and to see on what factors they differ we made use of discriminant function analysis. Some of our main conclusions are that radical inventions are to a higher degree based on existing knowledge than non-radical inventions. Also the combination of emergent and mature knowledge is more important for radical inventions. A further result that follows from our analysis is that radical inventions are induced by the recombination over more knowledge domains as compared to non-radical inventions. Our research hints also on the importance of alliances and an open innovation system for the development of radical inventions.radical inventions, patents, organizational learning, alliances

Incomplete meiotic sex chromosome inactivation in the domestic dog

Background: In mammalian meiotic prophase, homologous chromosome recognition is aided by formation and repair of programmed DNA double-strand breaks (DSBs). Subsequently, stable associations form through homologous chromosome synapsis. In male mouse meiosis, the largely heterologous X and Y chromosomes synapse only in their short pseudoautosomal regions (PARs), and DSBs persist along the unsynapsed non-homologous arms of these sex chromosomes. Asynapsis of these arms and the persistent DSBs then trigger transcriptional silencing through meiotic sex chromosome inactivation (MSCI), resulting in formation of the XY body. This inactive state is partially maintained in post-meiotic haploid spermatids (postmeiotic sex chromatin repression, PSCR). For the human, establishment of MSCI and PSCR have also been reported, but X-linked gene silencing appears to be more variable compared to mouse. To gain more insight into the regulation and significance of MSCI and PSCR among different eutherian species, we have performed a global analysis of XY pairing dynamics, DSB repair, MSCI and PSCR in the domestic dog (Canis lupus familiaris), for which the complete genome sequence has recently become available, allowing a thorough comparative analyses. Results: In addition to PAR synapsis between X and Y, we observed extensive self-synapsis of part of the dog X chromosome, and rapid loss of known markers of DSB repair from that part of the X. Sequencing of RNA from purified spermatocytes and spermatids revealed establishment of MSCI. However, the self-synapsing region of the X displayed higher X-linked gene expression compared to the unsynapsed area in spermatocytes, and was post-meiotically reactivated in spermatids. In contrast, genes in the PAR, which are expected to escape MSCI, were expressed at very low levels in both spermatocytes and spermatids. Our comparative analysis was then used to identify two X-linked genes that may escape MSCI in spermatocytes, and 21 that are specifically re-activated in spermatids of human, mouse and dog. Conclusions: Our data indicate that MSCI is incomplete in the dog. This may be partially explained by extensive, but transient, self-synapsis of the X chromosome, in association with rapid completion of meiotic DSB repair. In addition, our comparative analysis identifies novel candidate male fertility genes