943 resultados para Self-etching adhesive systems


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Rembrandt van Rijn; 2 33/64 in.x 2 23/64 in.; etching on paper

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Rembrandt van Rijn; 3 25/32 in.x 2 63/64 in.; etching on paper

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Rembrandt van Rijn; 7 3/4 in.x 6 27/64 in.; etching on paper

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Rembrandt van Rijn; 4 3/32 in.x 3 45/64 in.; etching on paper

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"Technical report AFFDL-TR-67-18"

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Rembrandt van Rijn; 8 5/32 in.x 6 29/64 in.; etching on paper

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Rembrandt van Rijn; 8 5/64 in.x 6 29/64 in.; etching on paper

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Thesis (Ph.D.)--University of Washington, 2016-06

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The anterior adhesive system of the oncomiracidium and adult of Merizocotyle icopae (Monogenea: Monocotylidae) were compared. The oncomiracidium has one ventrally placed aperture on either side of the head near the anterior extremity. In the adult, there are three ventrally placed apertures on either side of the head region. Both systems have three types of electron-dense secretory bodies opening into each aperture. A rod-shaped secretion (S1) and a small electron dense ovoid secretion (S2) are common to larvae and adults. The third secretion type differs: in adults, it is a large, spherical (S3) type but in larvae, it is an ovoid (S4) body. S4 bodies do occur in adults, but appear to be secreted as a general body secretion. An additional anteromedian secretion (S5) is also present in the oncomiracidium, but is not secreted into the anterior apertures. Homology and function of secretions are discussed.

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Despite the typically low population densities and animal-mediated pollination of tropical forest trees, outcrossing and long-distance pollen dispersal are the norm. We reviewed the genetic literature on mating systems and pollen dispersal for neotropical trees to identify the ecological and phylogenetic correlates. The 36 studies surveyed found >90% outcrossed mating for 45 hermaphroditic or monoecious species. Self-fertilization rates varied inversely with population density and showed phylogenetic and geographic trends. The few direct measures of pollen flow (N = 11 studies) suggest that pollen dispersal is widespread among low-density tropical trees, ranging from a mean of 200 m to over 19 km for species pollinated by small insects or bats. Future research needs to examine (1) the effect of inbreeding depression on observed outcrossing rates, (2) pollen dispersal in a wide range of pollination syndromes and ecological classes, (3) and the range of variation of mating system expression at different hierarchical levels, including individual, seasonal, population, ecological, landscape and range wide.

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The diagrammatic strong-coupling perturbation theory (SCPT) for correlated electron systems is developed for intersite Coulomb interaction and for a nonorthogonal basis set. The construction is based on iterations of exact closed equations for many - electron Green functions (GFs) for Hubbard operators in terms of functional derivatives with respect to external sources. The graphs, which do not contain the contributions from the fluctuations of the local population numbers of the ion states, play a special role: a one-to-one correspondence is found between the subset of such graphs for the many - electron GFs and the complete set of Feynman graphs of weak-coupling perturbation theory (WCPT) for single-electron GFs. This fact is used for formulation of the approximation of renormalized Fermions (ARF) in which the many-electron quasi-particles behave analogously to normal Fermions. Then, by analyzing: (a) Sham's equation, which connects the self-energy and the exchange- correlation potential in density functional theory (DFT); and (b) the Galitskii and Migdal expressions for the total energy, written within WCPT and within ARF SCPT, a way we suggest a method to improve the description of the systems with correlated electrons within the local density approximation (LDA) to DFT. The formulation, in terms of renormalized Fermions LIDA (RF LDA), is obtained by introducing the spectral weights of the many electron GFs into the definitions of the charge density, the overlap matrices, effective mixing and hopping matrix elements, into existing electronic structure codes, whereas the weights themselves have to be found from an additional set of equations. Compared with LDA+U and self-interaction correction (SIC) methods, RF LDA has the advantage of taking into account the transfer of spectral weights, and, when formulated in terms of GFs, also allows for consideration of excitations and nonzero temperature. Going beyond the ARF SCPT, as well as RF LIDA, and taking into account the fluctuations of ion population numbers would require writing completely new codes for ab initio calculations. The application of RF LDA for ab initio band structure calculations for rare earth metals is presented in part 11 of this study (this issue). (c) 2005 Wiley Periodicals, Inc.

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We have previously shown that a division of the f-shell into two subsystems gives a better understanding of the cohesive properties as well the general behavior of lanthanide systems. In this article, we present numerical computations, using the suggested method. We show that the picture is consistent with most experimental data, e.g., the equilibrium volume and electronic structure in general. Compared with standard energy band calculations and calculations based on the self-interaction correction and LIDA + U, the f-(non-f)-mixing interaction is decreased by spectral weights of the many-body states of the f-ion. (c) 2005 Wiley Periodicals, Inc.

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Several mechanisms for self-enhancing feedback instabilities in marine ecosystems are identified and briefly elaborated. It appears that adverse phases of operation may be abruptly triggered by explosive breakouts in abundance of one or more previously suppressed populations. Moreover, an evident capacity of marine organisms to accomplish extensive geographic habitat expansions may expand and perpetuate a breakout event. This set of conceptual elements provides a framework for interpretation of a sequence of events that has occurred in the Northern Benguela Current Large Marine Ecosystem (off south-western Africa). This history can illustrate how multiple feedback loops might interact with one another in unanticipated and quite malignant ways, leading not only to collapse of customary resource stocks but also to degradation of the ecosystem to such an extent that disruption of customary goods and services may go beyond fisheries alone to adversely affect other major global ecosystem concerns (e.g. proliferations of jellyfish and other slimy, stingy, toxic and/or noxious organisms, perhaps even climate change itself, etc.). The wisdom of management interventions designed to interrupt an adverse mode of feedback operation is pondered. Research pathways are proposed that may lead to improved insights needed: (i) to avoid potential 'triggers' that might set adverse phases of feedback loop operation into motion; and (ii) to diagnose and properly evaluate plausible actions to reverse adverse phases of feedback operation that might already have been set in motion. These pathways include the drawing of inferences from available 'quasi-experiments' produced either by short-term climatic variation or inadvertently in the course of biased exploitation practices, and inter-regional applications of the comparative method of science.

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This thesis deals with the problematic of the business systems systemic purpose definition. The definition of the systemic purpose, which is regarded as the utmost expression of the system's purposefulness, is to be achieved by ensuring the participation of all the stakeholders, if possible, who affect or they are affected by the business system's operations. The nature of participation, defined as a process of the stakeholders' perceptual exchanges, is deemed to be problematic in itself due to the influence exerted upon it by organisational power, coercion and false consciousness. The main focus of the thesis then is to make aware and provide the stakeholders with an explicit philosophical pedestal and a set of principles upon which a meta- epistemological framework for the enquiry of the business system's purposeful behaviour is developed. In addition, the thesis focuses on the development of a methodology that can be used by the stakeholders to achieve self-knowledge through the critical and systemic examination of their normative presuppositions, about the business system, at both sociological as well as the psychological levels concurrently and the subsequent development of an organisational intrinsically motivated information system. According to the critical systems philosophy and principles, developed in this thesis, normative presuppositions define the stakeholders' perceptions about the purposeful behaviour of the business system they perceived as having a material, an informational and/or an emacipatory stake (human interest) in. The methodology will provide Information Systems that demonstrably improve coordination of organisational activities by enabling the development and maintenance of a single/multifaceted view of purpose throughout organisations.