9,492 research outputs found

    On power bounded operators with holomorphic eigenvectors, II

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    In [U] (among other results), M. Uchiyama gave the necessary and sufficient conditions for contractions to be similar to the unilateral shift SS of multiplicity 11 in terms of norm-estimates of complete analytic families of eigenvectors of their adjoints. In [G2], it was shown that this result for contractions can't be extended to power bounded operators. Namely, a cyclic power bounded operator was constructed which has the requested norm-estimates, is a quasiaffine transform of SS, but is not quasisimilar to SS. In this paper, it is shown that the additional assumption on a power bounded operator to be quasisimilar to SS (with the requested norm-estimates) does not imply similarity to SS. A question whether the criterion for contractions to be similar to SS can be generalized to polynomially bounded operators remains open. Also, for every cardinal number 2≀N≀∞2\leq N\leq \infty a power bounded operator TT is constructed such that TT is a quasiaffine transform of SS and dim⁥ker⁥T∗=N\dim\ker T^*=N. This is impossible for polynomially bounded operators. Moreover, the constructed operators TT have the requested norm-estimates of complete analytic families of eigenvectors of T∗T^*

    FUNCTIONAL AND BIOCHEMICAL CONSEQUENCES OF SINGLE NUCLEOTIDE POLYMORPHISMS IN THE HUMAN VESICULAR MONOAMINE TRANSPORTER 1 GENE (SLC18A1) By Sally Gamal Shukry, B.S.

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    Abstract FUNCTIONAL AND BIOCHEMICAL CONSEQUENCES OF SINGLE NUCLEOTIDE POLYMORPHISMS IN THE HUMAN VESICULAR MONOAMINE TRANSPORTER 1 GENE (SLC18A1) By Sally Gamal Shukry, B.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology at Virginia Commonwealth University. Virginia Commonwealth University, 2012 Major Advisor: Jennifer K. Stewart Associate Professor and Graduate Director, Department of Biology Single nucleotide polymorphisms (SNP) in the human VMAT1 gene (SLC18A1) have been associated with schizophrenia in three different populations: Han Chinese, Western European and Japanese. Effects of these mutations on transport function of the hVMAT1 protein have not been reported. The goal of this study was to investigate functional and biochemical differences in human VMAT1 proteins with a threonine or proline at amino acid position 4 (Thr4Pro) and a serine or threonine at position 98 (Ser98Thr). COS1 cells were transfected with variant SNPs coding for 4Thr/98Ser, 4Pro/98Ser, or 4Thr98Thr. Western blotting demonstrated robust over expression of the genes and no differences in electrophoretic mobility of the proteins. Maximal transport of serotonin by the VMAT1 protein with 4Pro/98Ser was less than that of the 4Thr/98Ser or the 4Thr/98Thr. Response of the 4Pro/Ser98 to the VMAT inhibitor reserpine was lower than that of the 4Thr/98Thr. These findings suggest mechanisms for human VMAT1 links to schizophrenia

    Presupposition, perceptional relativity and translation theory

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    The intertwining of assertions and presuppositions in utterances affects the way a text is perceived in the source language (SL) and the target language (TL). Presuppositions can be thought of as shared assumptions that form the background of the asserted meaning. To translate presuppositions as assertions, or vice versa, can distort the thematic meaning of the SL text and produce a text with a different information structure. Since a good translation is not simply concerned with transferring the propositional content of the SL text, but also its other semantic and pragmatic components, including thematic meaning, a special attention should be accorded to the translation of presupposition. This article examines the intrinsic relation between presupposition and thematic meaning, why the concept is relevant to translation theory, and how presupposition can affect the structure and understanding of discourse. Unshared presuppositions are major obstacles in translation, as cultural concepts may be conveyed through expressions that yield presuppositions. To attain an optimal proximity to the SL text, presupposition needs to be singled out as a distinct aspect of meaning, and distinctions need to be made between definite and indefinite meaning, topic and comment, topic and focus, presupposition and entailment, and presupposition and implicature

    VERTICAL R&D SPILLOVERS, COOPERATION, MARKET STRUCTURE, AND INNOVATION

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    This paper studies vertical R&D spillovers between upstream and downstream firms. The model incorporates two vertically related industries, with horizontal spillovers within each industry and vertical spillovers between the two industries. Four types of R&D cooperation are studied: no cooperation, horizontal cooperation, vertical cooperation, and simultaneous horizontal and vertical cooperation. Vertical spillovers always increase R&D and welfare, while horizontal spillovers may increase or decrease them. The comparison of cooperative settings in terms of R&D shows that no setting uniformly dominates the others. Which type of cooperation yields more R&D depends on horizontal and vertical spillovers, and market structure. The ranking of cooperative structures hinges on the signs and magnitudes of three competitive externalities (vertical, horizontal, and diagonal) which capture the effect of the R&D of a firm on the profits of other firms. One of the basic results of the strategic investment literature is that cooperation between competitors increases (decreases) R&D when horizontal spillovers are high (low); the model shows that this result does not necessarily hold when vertical spillovers and vertical cooperation are taken into account. The paper proposes a theory of innovation and market structure, showing that the relation between innovation and competition depends on horizontal spillovers, vertical spillovers, and cooperative settings. The private incentives for R&D cooperation are addressed. It is found that buyers and sellers have divergent interests regarding the choice of cooperative settings and that spillovers increase the likelihood of the emergence of cooperation in a decentralized equilibrium.Vertical R&D spillovers, Market structure, Innovation, Vertical R&D cooperation, R&D policy

    Production Technology, Information Technology, and Vertical Integration under Asymmetric Information

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    The paper addresses the effect of technological progress on the frontiers of the firm, building on transaction cost theory and agency theory. The model incorporates four types of costs: production, coordination, management, and transaction costs. The market has lower production costs, but higher coordination costs, than the firm. A principal-two agents framework with adverse selection and moral hazard is adopted. It is found that technological progress in production and information technologies tend to have diametrically opposite effects on procurement. In general, progress in production technology leads to more vertical integration, whereas progress in information technology leads to more subcontracting. When technological change concerns the level of costs, its effect on procurement depends on the cost differential between the firm and the market, and on the relative importance of production and coordination costs; whereas, when technological change affects the effect or disutility of effort, its impact on procurement is unambiguous. The paper provides an explanation for the changing effect of technological progress on procurement throughout the twentieth century: why it favoured vertical integration historically, and why it favours subcontracting (or has a mixed effect) today. This explanation relies on the implication of the evolution of the relative importance of production and coordination activities for the relationship between technological progress and vertical integration. The paper constitutes a bridge between contractual explanations and technological explanations of the existence and frontiers of the firm. Cet article analyse l'effet du changement technologique sur les frontiÚres de la firme en se basant sur la théorie des coûts de transaction et la théorie de l'agence. Le modÚle incorpore quatre types de coûts: coûts de production, de coordination, de management et de transaction. Le marché a des coûts de production plus faibles, mais des coûts de coordination plus élevés, que la firme. L'analyse est effectuée dans un cadre principal-deux agents, avec antisélection et risque moral. Les changement technologiques concernant la technologie de production et les technologies de l'information entraßnent des effets diamétralement opposés sur l'intégration verticale. En général, le changement technique concernant la technologie de production se traduit par davantage d'intégration verticale, alors que le changement technique concernant les technologies de l'information se traduit par davantage d'impartition. Lorsque le changement technologique concerne le niveau des coûts, son effet sur l'impartition dépend du différentiel de coûts entre la firme et le marché, et de l'importance relative des coûts de production et de coordination; tandis que, lorsque le changement technologique concerne les efforts de réduction des coûts, son effet est sans ambiguïté. Le papier propose une explication du changement dans l'effet du progrÚs technique sur l'impartition durant le vingtiÚme siÚcle: pourquoi il a favorisé l'intégration verticale historiquement, et favorise l'impartition (ou du moins a un effet ambigu) aujourd'hui. L'explication repose sur l'impact de l'évolution de l'importance relative des activités de production et de coordination sur la relation entre le progrÚs technique et l'intégration verticale. Cet article constitue un mariage entre les explications contractuelles et les explications technologiques de l'existence et des frontiÚres de la firme.Transaction costs, Asymmetric and private information, Markets vs. hierarchies, Vertical integration, Technological change, Information technology, Coûts de transaction, Information privée et asymétrique, Marchés vs. hiérarchies, Intégration verticale, Changement Technologique, Technologies de l'information
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