Adjoint bi-continuous semigroups and semigroups on the space of measures

For a given bi-continuous semigroup T on a Banach space X we define its adjoint on an appropriate closed subspace X^o of the norm dual X'. Under some abstract conditions this adjoint semigroup is again bi-continuous with respect to the weak topology (X^o,X). An application is the following: For K a Polish space we consider operator semigroups on the space C(K) of bounded, continuous functions (endowed with the compact-open topology) and on the space M(K) of bounded Baire measures (endowed with the weak*-topology). We show that bi-continuous semigroups on M(K) are precisely those that are adjoints of a bi-continuous semigroups on C(K). We also prove that the class of bi-continuous semigroups on C(K) with respect to the compact-open topology coincides with the class of equicontinuous semigroups with respect to the strict topology. In general, if K is not Polish space this is not the case

The Influence of Strategic Patenting on Companies’ Patent Portfolios

This paper analyses whether strategic motives for patenting influence the characteristics of companies’ patent portfolios. We use the number of citations and oppositions to represent these characteristics. The investigation is based on survey and patent data from German companies. We find clear evidence that the companies’ patenting strategies explain the characteristics of their patent portfolios. First, companies using patents to protect their technological knowledge base receive a higher number of citations for their patents. Second, the motive of offensive – but not of defensive – blocking is related to a higher incidence of oppositions, whereas companies using patents as bartering chips in collaborations receive fewer oppositions to their patents

Ligand Activation of the Prokaryotic Pentameric Ligand-Gated Ion Channel ELIC

While the pentameric ligand-gated ion channel ELIC has recently provided first insight into the architecture of the family at high resolution, its detailed investigation was so far prevented by the fact that activating ligands were unknown. Here we describe a study on the functional characterization of ELIC by electrophysiology and X-ray crystallography. ELIC is activated by a class of primary amines that include the neurotransmitter GABA at high micro- to millimolar concentrations. The ligands bind to a conserved site and evoke currents that slowly desensitize over time. The protein forms cation selective channels with properties that resemble the nicotinic acetylcholine receptor. The high single channel conductance and the comparably simple functional behavior make ELIC an attractive model system to study general mechanisms of ion conduction and gating in this important family of neurotransmitter receptors

Conformational changes in α7 acetylcholine receptors underlying allosteric modulation by divalent cations

Allosteric modulation of membrane receptors is a widespread mechanism by which endogenous and exogenous agents regulate receptor function. For example, several members of the nicotinic receptor family are modulated by physiological concentrations of extracellular calcium ions. In this paper, we examined conformational changes underlying this modulation and compare these with changes evoked by ACh. Two sets of residues in the α7 acetylcholine receptor extracellular domain were mutated to cysteine and analyzed by measuring the rates of modification by the thiol-specific reagent 2-aminoethylmethane thiosulfonate. Using Ba2+ as a surrogate for Ca2+, we found a divalent-dependent decrease the modification rates of cysteine substitutions at M37 and M40, residues at which rates were also slowed by ACh. In contrast, Ba2+ had no significant effect at N52C, a residue where ACh increased the rate of modification. Thus divalent modulators cause some but not all of the conformational effects elicited by agonist. Cysteine substitution of either of two glutamates (E44 or E172), thought to participate in the divalent cation binding site, caused a loss of allosteric modulation, yet Ba2+ still had a significant effect on modification rates of these residues. In addition, the effect of Ba2+ at these residues did not appear to be due to direct occlusion. Our data demonstrate that modulation by divalent cations involves substantial conformational changes in the receptor extracellular domain. Our evidence also suggests the modulation occurs via a binding site distinct from one which includes either (or both) of the conserved glutamates at E44 or E172

The interplay of agency, culture and networks in field evolution

We examine organizational field change instigated by activists. Contrary to existing views emphasizing incumbent resistance, we suggest that collaboration between incumbents and challenger movements may emerge when a movement's cultural and relational fabric becomes moderately structured, creating threats and market opportunities but remaining permeable to external influence. We also elucidate how lead incumbents' attempts at movement cooptation may be deflected through distributed brokerage. The resulting confluence of cultural and relational "structuration" between movement and field accelerates the pace but dilutes the radicalness of institutional innovation, ensuring ongoing, incremental field change. Overall, this article contributes to the emergent literature on field dynamics by uncovering the evolution and outcomes of collaborative work at the intersection of social movements and incumbent fields

Research on Markets for Inventions and Implications for R&D Allocation Strategies

Several streams of literature have examined the phenomenon of “markets for inventions”, that is, the trade of elements of knowledge which are “disembodied” from individuals, organizations, and products. The aims of this paper are to bring together the various streams of research in this area and discuss their major assumptions and limitations, in order to provide a comprehensive framework for understanding the phenomenon, and identify promising paths for future research. We start our review by identifying the object of market exchange—that is, an invention whose knowledge has been codified and disembodied from individuals, organizations, or artifacts. We then identify those factors that enable firms to trade inventions, distinguishing between institutional-, firm-, and industry-level factors. We close our analysis of the extant literature by discussing the implications of markets for inventions for firm behavior and performance. Against this background, we highlight an important avenue for future research. A neglected implication of the development of invention markets is that firms are confronted with a wide variety of technological paths from which to choose, because the opportunity to acquire technologies on the market offers them a greater variety that can their internal R&D departments. However, the streams of research on markets for inventions and on R&D allocation strategies have been surprisingly disconnected so far. Hence, in the final section, we start to establish and explore the link between these literatures, and to identify a research agenda in this domain