338 research outputs found
Charge Delocalization in Self-Assembled Mixed-Valence Aromatic Cation Radicals
The spontaneous assembly of aromatic cation radicals (D+•) with their neutral counterpart (D) affords dimer cation radicals (D2+•). The intermolecular dimeric cation radicals are readily characterized by the appearance of an intervalence charge-resonance transition in the NIR region of their electronic spectra and by ESR spectroscopy. The X-ray crystal structure analysis and DFT calculations of a representative dimer cation radical (i.e., the octamethylbiphenylene dimer cation radical) have established that a hole (or single positive charge) is completely delocalized over both aromatic moieties. The energetics and the geometrical considerations for the formation of dimer cation radicals is deliberated with the aid of a series of cyclophane-like bichromophoric donors with drastically varied interplanar angles between the cofacially arranged aryl moieties. X-ray crystallography of a number of mixed-valence cation radicals derived from monochromophoric benzenoid donors established that they generally assemble in 1D stacks in the solid state. However, the use of polychromophoric intervalence cation radicals, where a single charge is effectively delocalized among all of the chromophores, can lead to higher-order assemblies with potential applications in long-range charge transport. As a proof of concept, we show that a single charge in the cation radical of a triptycene derivative is evenly distributed on all three benzenoid rings and this triptycene cation radical forms a 2D electronically coupled assembly, as established by X-ray crystallography
International Coercion, Emulation and Policy Diffusion: Market-Oriented Infrastructure Reforms, 1977-1999
Why do some countries adopt market-oriented reforms such as deregulation, privatization and liberalization of competition in their infrastructure industries while others do not? Why did the pace of adoption accelerate in the 1990s? Building on neo-institutional theory in sociology, we argue that the domestic adoption of market-oriented reforms is strongly influenced by international pressures of coercion and emulation. We find robust support for these arguments with an event-history analysis of the determinants of reform in the telecommunications and electricity sectors of as many as 205 countries and territories between 1977 and 1999. Our results also suggest that the coercive effect of multilateral lending from the IMF, the World Bank or Regional Development Banks is increasing over time, a finding that is consistent with anecdotal evidence that multilateral organizations have broadened the scope of the “conditionality” terms specifying market-oriented reforms imposed on borrowing countries. We discuss the possibility that, by pressuring countries into policy reform, cross-national coercion and emulation may not produce ideal outcomes.http://deepblue.lib.umich.edu/bitstream/2027.42/40099/3/wp713.pd
Multiple Phenotypes in Adult Mice following Inactivation of the Coxsackievirus and Adenovirus Receptor (Car) Gene
To determine the normal function of the Coxsackievirus and Adenovirus Receptor (CAR), a protein found in tight junctions and other intercellular complexes, we constructed a mouse line in which the CAR gene could be disrupted at any chosen time point in a broad spectrum of cell types and tissues. All knockouts examined displayed a dilated intestinal tract and atrophy of the exocrine pancreas with appearance of tubular complexes characteristic of acinar-to-ductal metaplasia. The mice also exhibited a complete atrio-ventricular block and abnormal thymopoiesis. These results demonstrate that CAR exerts important functions in the physiology of several organs in vivo
Are social innovation paradigms incommensurable?
This paper calls attention to the problematic use of the concept of social innovation which remains undefined despite its proliferation throughout academic and policy discourses. Extant research has thus far failed to capture the socio-political contentions which surround social innovation. This paper therefore draws upon the work of Thomas Kuhn and conducts a paradigmatic analysis of the field of social innovation which identifies two emerging schools: one technocratic, the other democratic. The paper identifies some of the key thinkers in each paradigm and explains how the struggle between these two paradigms reveals itself to be part of a broader conflict between neoliberalism and it opponents and concludes by arguing that future research focused upon local contextualised struggles will reveal which paradigm is in the ascendancy
A novel aspect of the structure of the avian thymic medulla.
We provide evidence for the compartmentalization of the avian thymic medulla and identify the avian thymic dendritic cell. The thymic anlage develops from an epithelial cord of the branchial endoderm. Branches of the cord are separated by primary septae of neural crest origin. The dilation of the primary septae produces the keratin-negative area (KNA) of the thymic medulla and fills the gaps of the keratin-positive network (KPN). Morphometric analysis indicates that the KNA takes up about half of the volume of the thymic medulla, which has reticular connective tissue, like peripheral lymphoid organs. The KNA receives blood vessels and in addition to pericytes, the myoid cells of striated muscle structure occupy this area. The myoid cells are of branchial arch or prechordal plate origin providing indirect evidence for the neural crest origin of the KNA. The marginal epithelial cells of the KPN co-express keratin and vimentin intermediate filaments, which indicate their functional peculiarity. The basal lamina of the primary septum is discontinuous on the surface of the KPN providing histological evidence for the loss of the blood-thymus barrier in the medulla. In the center of the KNA, the dendritic cells lie in close association with blood vessels, whereas the B-cells accumulate along the KPN. The organization of the KPN and KNA increases the "surface" of the so-called cortico-medullary border, thereby contributing to the efficacy of central tolerance
Investigation of epimer formation in amide coupling reactions: an experiment for advanced undergraduate students
An experiment is described to investigate how the choice of coupling agent and reaction conditions affects the ratio of epimers formed in the sensitive amide-coupling reaction between N-Boc or N-benzoyl (R)-phenylglycine and (S)-valine methyl ester. The experiment, which is suitable for third-year undergraduates, is designed to teach about important synthetic methods and reaction mechanisms, and to develop skills in designing experiments, data analysis, and team work
Cycles of polarization and settlement:Diffusion and transformation in the macroeconomic policy field
Rethinking Human-Animal Relations: The Critical Role of Social Psychology
People deeply value their social bonds with companion animals, yet routinely devalue other animals, considering them mere commodities to satisfy human interests and desires. Despite the inherently social and intergroup nature of these complexities, social psychology is long overdue in integrating human-animal relations in its theoretical frameworks. The present body of work brings together social psychological research advancing our understanding of: 1) the factors shaping our perceptions and thinking about animals as social groups, 2) the complexities involved in valuing (caring) and devaluing (exploiting) animals, and 3) the implications and importance of human-animal relations for human intergroup relations. In this article, we survey the diversity of research paradigms and theoretical frameworks developed within the intergroup relations literature that are relevant, perchance critical, to the study of human-animal relations. Furthermore, we highlight how understanding and rethinking human-animal relations will eventually lead to a more comprehensive understanding of many human intergroup phenomena
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