963 resultados para Amelogénesis imperfect


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Early modern play-texts present numerous puzzles for scholars interested in ascertaining how plays were (or may have been) staged. the principal evidence of course for a notional "reconstruction" of practices is the apparatus of stage directions, augmented by indications in the dialogue. in conjunction a joining-of-the-dots is often possible, at least in broad-brush terms. But as is well known, the problem is that stage directions tend to be incomplete, imprecise, inaccurate ­ or missing altogether; more significantly, even when present they offer only slight and indirect evidence of actual stagecraft. Some stage directions are rather more "literary" than "theatrical" in provenance, and in any case to the extent that they do serve the reader (early modern or modern) they cannot be regarded as providing a record of stage practice. After all, words can be no more than imperfect substitutes for (and of another order from) the things they represent. For the most part directions serve as a guide that provides the basis for reasonable interpretation informed by our knowledge of theatre architecture, technology, and comparable play-situations, rather than concrete evidence of actual practice. Quite how some stage business was carried out remains uncertain, leaving the scholar little option but to hypothesize solutions. One such conundrum arises in christopher Marlowe's The Jew of Malta. the scenario in question is hardly an obscure one, but it has not been examined in detail, even by modern editors. the purpose of this essay is to explore what sense might be made of the surviving textual evidence, in combination with our knowledge of theatre architecture and playmaking culture in the late sixteenth century.

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Skillful and timely streamflow forecasts are critically important to water managers and emergency protection services. To provide these forecasts, hydrologists must predict the behavior of complex coupled human–natural systems using incomplete and uncertain information and imperfect models. Moreover, operational predictions often integrate anecdotal information and unmodeled factors. Forecasting agencies face four key challenges: 1) making the most of available data, 2) making accurate predictions using models, 3) turning hydrometeorological forecasts into effective warnings, and 4) administering an operational service. Each challenge presents a variety of research opportunities, including the development of automated quality-control algorithms for the myriad of data used in operational streamflow forecasts, data assimilation, and ensemble forecasting techniques that allow for forecaster input, methods for using human-generated weather forecasts quantitatively, and quantification of human interference in the hydrologic cycle. Furthermore, much can be done to improve the communication of probabilistic forecasts and to design a forecasting paradigm that effectively combines increasingly sophisticated forecasting technology with subjective forecaster expertise. These areas are described in detail to share a real-world perspective and focus for ongoing research endeavors.

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This paper explores the criticism that system dynamics is a ‘hard’ or ‘deterministic’ systems approach. This criticism is seen to have four interpretations and each is addressed from the perspectives of social theory and systems science. Firstly, system dynamics is shown to offer not prophecies but Popperian predictions. Secondly, it is shown to involve the view that system structure only partially, not fully, determines human behaviour. Thirdly, the field's assumptions are shown not to constitute a grand content theory—though its structural theory and its attachment to the notion of causality in social systems are acknowledged. Finally, system dynamics is shown to be significantly different from systems engineering. The paper concludes that such confusions have arisen partially because of limited communication at the theoretical level from within the system dynamics community but also because of imperfect command of the available literature on the part of external commentators. Improved communication on theoretical issues is encouraged, though it is observed that system dynamics will continue to justify its assumptions primarily from the point of view of practical problem solving. The answer to the question in the paper's title is therefore: on balance, no.

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This article examines the role played by ideas and their thinkers in Christopher Hill's histories of the English Revolution. Hill protested against a reductionist economic determinism with no place for the intrinsic power of ideas, but his account of ideas gave them a progressive logic parallel to, if not always easy to link with, that of economic development, and threatened to divorce them from their muddled and imperfect thinkers. This account of the logic of ideas had a striking impact on the way in which the more mainstream radicals of the English Revolution appeared in Hill's work, with both the Levellers and James Harrington being half assimilated to, and half pushed aside in favor of, the more thoroughgoing economic radicals who expressed, in however ragged a way, the intrinsic potential of their ideas. However, Hill's writings also betray a surprising attraction to religious over secular forms of radicalism.

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The chapter explores the role the World Trade Organization (WTO) played or, rather, did not play in the 2013 ‘recalibration’ of the CAP. It is organised as follows: first, a brief review of policy changes from 1992 to 2008 and their (apparent) conformability with evolving WTO rules; second, a re-examination of the relevance of the Agreement on Agriculture (AoA) in the mid-2010s; and, third, a short account of how WTO constraints were addressed by the European Commission and the European Parliament in the 2013 CAP reform debate.

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In 2003 the CAP underwent a significant reform. Despite a seemingly endless turmoil of CAP reform, in 2005 the British government pressed for a new reform debate, and in the European Council meeting of December 2005 secured a commitment for the Commission “to undertake a full, wide ranging review covering all aspects of EU spending, including the CAP, ...” But but the initiative petered out, and the CAP ‘reform’ package proposed by the Commission, and then adopted by the European Parliament and the Council of Ministers in 2013, fell well short of the UK’s initial ambition. The chapter attempts to explore the reasons leading to the UK’s failed policy initiative.

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This study investigates the possibility of native-like ultimate attainment by analyzing L2 knowledge of aspect as seen in the Preterit/Imperfect contrast of highly successful English L2 learners of Portuguese and Spanish. Building on innovative work by Montrul & Slabakova (2003) and Slabakova & Montrul (2003), we test knowledge of semantic entailments associated with the acquisition of [+/- perfective] features checked in higher AspP. Additionally, we investigate the possibility of a specific pattern of associated target-deviant L2 performance. We hypothesize that L2 performance can be affected by explicit positive evidence (pedagogical rules) despite otherwise demonstrable native-like competence. Indeed, the data reveal a pattern of target-deviant performance noted only in three specific contexts, all of which can be linked to traditional instruction: (a) with particular stative verbs not used in the Preterit (b) when preceded by certain adverbial phrases (e.g.,siempre) and (c) so-called semantic shifting verbs (e.g., sabía vs. supe).

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The issue of imperfect information plays a much more important role in financing “informationally opaque” small businesses than in financing large companies.1 This chapter examines the asymmetric information issue in entrepreneurial finance from two perspectives: the effects of relationship lending and the impacts of credit market concentration on entrepreneurial financial behavior. These two perspectives are strongly linked to each other via the asymmetric information issue in entrepreneurial finance. Existing literature has recognized the important role played by relationship lending in alleviating the problem of asymmetric information. However, mixed empirical results have been reported. For example, it has been found that the development of relationship lending can improve the availability of finance for small businesses borrowers (Petersen and Rajan, 1994) and reduce the costs of finance (Berger and Udell, 1995). Meanwhile, with monopoly power, banks may extract rents, in terms of charging higher-than-market interest rates, from small businesscustomers who have very concentrated banking relationships (Ongena and Smith, 2001). In addition, both favorable and unfavorable effects of credit market concentration on financing small businesses have been acknowledged. Small business borrowers may have to pay a higher-than-market price on loans (Degryse and Ongena, 2005) and are more likely to be financially constrained (Cetorelli, 2004) than in competitive markets. On the other hand, empirical studies have shown that market concentration create a strong motive for lenders to invest in private information from small business customers, and therefore a concentrated market is more efficient in terms of private information acquisition (Han et al., 2009b). The objective of this chapter is to investigate, by reviewing existing literature, the role played by relationship lending and the effects of market concentration on financing entrepreneurial businesses that are supposed to be informationally opaque. In the first section we review literature on the important role played by asymmetric information in entrepreneurial finance from two perspectives: asymmetric information and relationship lending, and the theoretical modeling of asymmetric information. Then we examine the relationship between capital market conditions and entrepreneurial finance and attempt to answer two questions: Why is the capital market condition important for entrepreneurial finance? and What are the effects of capital market conditions on entrepreneurial financial behavior in terms of discouraged borrowers, cash holding, and the availability and costs of finance?

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Working outward from Edward Kamau Brathwaite’s landmark 1974 essay, “The African Presence in Caribbean Literature,” this article explores the fuller history of the idea of Africa in anglophone Caribbean critical and literary works from the 1930s to the 2000s. It demonstrates that earlier, now forgotten Caribbean critics drew on imperfect and incomplete Caribbean literary imaginings of Africa to frame a counter-colonial politics of identity. The essay also brings back into view writings by Una Marson, Victor Stafford Reid, and Derek Walcott that expressed a different politics of solidarity based on the shared experience of colonial violence. Readings of recent literary works by Charlotte Williams and Nalo Hopkinson reveal the contemporary crafting of this relation around a heightened awareness of both presence and loss, history and imagination. Importantly, this gathering of sources and perspectives allows for an appreciation of the role that a reach toward Africa has played in articulations of Caribbeanness and its complex patterning of cultural co-belonging.

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Estrogen is an important steroid hormone that mediates most of its effects on regulation of gene expression by binding to intracellular receptors. The consensus estrogen response element (ERE) is a 13 bp palindromic inverted repeat with a three nucleotide spacer. However, several reports suggest that many estrogen target genes are regulated by diverse elements, such as imperfect EREs and ERE half sites (ERE 1/2),which are either the proximal or the distal half of the palindrome. To gain more insight into ERE half site-mediated gene regulation, we used a region from the estrogen-regulated chicken riboflavin carrier protein (RCP) gene promoter that contains ERE half sites. Using moxestrol, an analogue of estrogen and transient transfection of deletion and mutation containing RCP promoter/reporter constructs in chicken hepatoma (LMH2A) cells, we identified an estrogen response unit (ERU) composed of two consensus ERE 1/2 sites and one non-consensus ERE 1/2 site. Mutation of any of these sites within this ERU abolishes moxestrol response. Further, the ERU is able to confer moxestrol responsiveness to a heterologous promoter. Interestingly, RCP promoter is regulated by moxestrol in estrogen responsive human MCF-7 cells, but not in other cell lines such as NIH3T3 and HepG2 despite estrogen receptor-alpha (ER-�) co transfection. Electrophoretic mobility shift assays (EMSAs) with promoter regions encompassing the half sites and nuclear extracts from LMH2A cells show the presence of a moxestrol-induced complex that is abolished by a polyclonal anti-ER� antibody. Surprisingly, estrogen receptor cannot bind to these promoter elements in isolation. Thus, there appears to be a definite requirement for some other factor(s) in addition to estrogen receptor, for the generation of a suitable response of this promoter to estrogen. Our studies therefore suggest a novel mechanism of gene regulation by estrogen, involving ERE half sites without direct binding of ER to the cognate elements.

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Estrogen is an important steroid hormone that mediates most of its effects on regulation of gene expression by binding to intracellular receptors. The consensus estrogen response element (ERE) is a 13 bp palindromic inverted repeat with a three nucleotide spacer. However, several reports suggest that many estrogen target genes are regulated by diverse elements, such as imperfect EREs and ERE half sites (ERE 1/2), which are either the proximal or the distal half of the palindrome. To gain more insight into ERE half site-mediated gene regulation, we used a region from the estrogen-regulated chicken riboflavin carrier protein (RCP) gene promoter that contains ERE half sites. Using moxestrol, an analogue of estrogen and transient transfection of deletion and mutation containing RCP promoter/reporter constructs in chicken hepatoma (LMH2A) cells, we identified an estrogen response unit (ERU) composed of two consensus ERE 1/2 sites and one non-consensus ERE 1/2 site. Mutation of any of these sites within this ERU abolishes moxestrol response. Further, the ERU is able to confer moxestrol responsiveness to a heterologous promoter. Interestingly, RCP promoter is regulated by moxestrol in estrogen responsive human MCF-7 cells, but not in other cell lines such as NIH3T3 and HepG2 despite estrogen receptor-alpha (ER-�) co transfection. Electrophoretic mobility shift assays (EMSAs) with promoter regions encompassing the half sites and nuclear extracts from LMH2A cells show the presence of a moxestrol-induced complex that is abolished by a polyclonal anti-ER� antibody. Surprisingly, estrogen receptor cannot bind to these promoter elements in isolation. Thus, there appears to be a definite requirement for some other factor(s) in addition to estrogen receptor, for the generation of a suitable response of this promoter to estrogen. Our studies therefore suggest a novel mechanism of gene regulation by estrogen, involving ERE half sites without direct binding of ER to the cognate elements.

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The co-polar correlation coefficient (ρhv) has many applications, including hydrometeor classification, ground clutter and melting layer identification, interpretation of ice microphysics and the retrieval of rain drop size distributions (DSDs). However, we currently lack the quantitative error estimates that are necessary if these applications are to be fully exploited. Previous error estimates of ρhv rely on knowledge of the unknown "true" ρhv and implicitly assume a Gaussian probability distribution function of ρhv samples. We show that frequency distributions of ρhv estimates are in fact highly negatively skewed. A new variable: L = -log10(1 - ρhv) is defined, which does have Gaussian error statistics, and a standard deviation depending only on the number of independent radar pulses. This is verified using observations of spherical drizzle drops, allowing, for the first time, the construction of rigorous confidence intervals in estimates of ρhv. In addition, we demonstrate how the imperfect co-location of the horizontal and vertical polarisation sample volumes may be accounted for. The possibility of using L to estimate the dispersion parameter (µ) in the gamma drop size distribution is investigated. We find that including drop oscillations is essential for this application, otherwise there could be biases in retrieved µ of up to ~8. Preliminary results in rainfall are presented. In a convective rain case study, our estimates show µ to be substantially larger than 0 (an exponential DSD). In this particular rain event, rain rate would be overestimated by up to 50% if a simple exponential DSD is assumed.

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Complex networks obtained from real-world networks are often characterized by incompleteness and noise, consequences of imperfect sampling as well as artifacts in the acquisition process. Because the characterization, analysis and modeling of complex systems underlain by complex networks are critically affected by the quality and completeness of the respective initial structures, it becomes imperative to devise methodologies for identifying and quantifying the effects of the sampling on the network structure. One way to evaluate these effects is through an analysis of the sensitivity of complex network measurements to perturbations in the topology of the network. In this paper, measurement sensibility is quantified in terms of the relative entropy of the respective distributions. Three particularly important kinds of progressive perturbations to the network are considered, namely, edge suppression, addition and rewiring. The measurements allowing the best balance of stability (smaller sensitivity to perturbations) and discriminability (separation between different network topologies) are identified with respect to each type of perturbation. Such an analysis includes eight different measurements applied on six different complex networks models and three real-world networks. This approach allows one to choose the appropriate measurements in order to obtain accurate results for networks where sampling bias cannot be avoided-a very frequent situation in research on complex networks.

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Hypercycles are information integration systems which are thought to overcome the information crisis of prebiotic evolution by ensuring the coexistence of several short templates. For imperfect template replication, we derive a simple expression for the maximum number of distinct templates n(m). that can coexist in a hypercycle and show that it is a decreasing function of the length L of the templates. In the case of high replication accuracy we find that the product n(m)L tends to a constant value, limiting thus the information content of the hypercycle. Template coexistence is achieved either as a stationary equilibrium (stable fixed point) or a stable periodic orbit in which the total concentration of functional templates is nonzero. For the hypercycle system studied here we find numerical evidence that the existence of an unstable fixed point is a necessary condition for the presence of periodic orbits. (C) 2008 Elsevier Ltd. All rights reserved.

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After Modigliani and Miller (1958) presented their capital structure irrelevance proposition, analysis of corporate Önancing choices involving debt and equity instruments have generally followed two trends in the literature, where models either incorporate informational asymmetries or introduce tax beneÖts in order to explain optimal capital structure determination (Myers, 2002). None of these features is present in this paper, which develops an asset pricing model with the purpose of providing a positive theory of corporate capital structure by replicating main aspects of standard contractual practice observed in real markets. Alternatively, the imperfect market structure of the economy is tailored to match what is most common in corporate reality. Allowance for default on corporate debt with an associated penalty of seizure of Örmís future cash áows by creditors is introduced, for instance. In this context, a qualitative assessment of Önancial managersídecisions is carried out through numerical procedures.