997 resultados para exchange interaction


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Considerable experimental evidence suggests that non-pecuniary motives must be addressed when modeling behavior in economic contexts. Recent models of non-pecuniary motives can be classified as either altruism- based, equity-based, or reciprocity-based. We estimate and compare leading approaches in these categories, using experimental data. We then offer a flexible approach that nests the above three approaches, thereby allowing for nested hypothesis testing and for determining the relative strength of each of the competing theories. In addition, the encompassing approach provides a functional form for utility in different settings without the restrictive nature of the approaches nested within it. Using this flexible form for nested tests, we find that intentional reciprocity, distributive concerns, and altruistic considerations all play a significant role in players' decisions.

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Crystallization of anatectic melts in high-temperature metamorphic terrains releases volatile-rich magmas that can be transported into adjacent lithologies. This study addresses the variations in the oxygen, boron and hydrogen isotopic composition of aplite-pegmatite dikes that formed during the crystallization of anatectic melts in regional high-temperature metamorphism on the island of Naxos, Greece, and propagated upward into the overlying sequences of metamorphic schist. The transport distance of these dikes was increased through a significant horizontal component of travel that was imposed by contemporaneous low-angle extensional shearing. Laser fluorination oxygen isotope analyses of quartz, tourmaline, garnet, and biotite mineral separates from the aplite-pegmatite dikes show a progressive rise in delta(18)O values with increasing distance from the core. Oxygen isotope fractionations among quartz, tourmaline, and garnet show temperature variations from > 700degreesC down to similar to400degreesC. This range is considered to reflect isotopic fractionation beginning with crystallization at high temperatures in water-undersaturated conditions and then evolving through lower temperature crystallization and retrograde sub-solidus exchange. Two processes are examined for the cause of the progressive increase in delta(18)O values: (1) heterogeneous delta(18)O sources and (2) fluid-rock exchange between the aplite/pegmatite magmas and their host rock. Although the former process cannot be ruled out, there is as yet no evidence in the exposed sequences on Naxos for the presence of a suitable high delta(18)O magma source. In contrast, a tendency for the delta(18)O of quartz in the aplite/pegmatite dikes to approach that of the quartz in the metamorphic rock suggests that fluid-rock exchange with the host rock may potentially be an important process. Advection of fluid into the magma is examined based on Darcian fluid flow into an initially water-undersaturated buoyantly propagating aplitic dike magma. It is shown that such advective flow could only account for part of the O-18-enrichment, unless it were amplified by repeated injection of magma pulses, fluid recycling, and deformation-assisted post-crystallization exchange. The mechanism is, however, adequate to account for hydrogen isotope equilibration between dike and host rock. In contrast, variations in the delta(11)B values of tourmalines suggest that B-11/B-10 fractionation during crystallization and/or magma degassing was the major control of boron geochemistry rather than fluid-rock interaction and that the boron isotopic system was decoupled from that of oxygen. Copyright (C) 2003 Elsevier Ltd.

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In this paper we study the interaction between ownership structure and customer satisfaction, and their impact on a firm's brand equity. We find that customer satisfaction has a positive direct effect on brand equity but an indirect negative one, through reductions in ownership concentration. This latter effect emerges when managers are focused mainly on satisfying customers. It gives out a warning signal that highlights the perverse effect of implementing policies focused excessively on satisfying customers at the expense of shareholders, on a firm's brand equity. We demonstrate our theoretical contention, empirically, making use of an incomplete panel data comprising 69 firms from 11 different nations for the period 2002-2005.

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Relatively homogeneous oxygen isotope compositions of amphibole, clinopyroxene, and olivine separates (+5.2 to +5.7parts per thousand relative to VSMOW) and neodymium isotope compositions (epsilon(Nd(T)) = -0.9 to -1.8 for primary magmatic minerals and epsilon(Nd(T)) = -0.1 and -0.5 for mineral separates from late-stage pegmatites and hydrothermal veins) from the alkaline to agpaitic llimaussaq intrusion, South Greenland, indicate a closed system evolution of this igneous complex and support a mantle derivation of the magma. In contrast to the homogeneous oxygen and neodymium isotopic data, deltaD values for hand-picked amphibole separates vary between -92 and -232parts per thousand and are among the most deuterium-depleted values known from igneous amphiboles. The calculated fluid phase coexisting with these amphiboles has a homogeneous oxygen isotopic composition within the normal range of magmatic waters, but extremely heterogeneous and low D/H ratios, implying a decoupling of the oxygen- and hydrogen isotope systems. Of the several possibilities that can account for such unusually low deltaD values in amphiboles (e.g., late-stage hydrothermal exchange with meteoric water, extensive magmatic degassing, contamination with organic matter, and/or effects of Fe-content and pressure on amphibole-water fractionation) the most likely explanation for the range in deltaD values is that the amphiboles have been influenced by secondary interaction and reequilibration with D-depleted fluids obtained through late-magmatic oxidation of internally generated CH(4) and/or H(2). This interpretation is consistent with the known occurrence of abundant magmatic CH(4) in the Ilimaussaq rocks and with previous studies on the isotopic compositions of the rocks and fluids. Copyright (C) 2004 Elsevier Ltd.

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Efficient initiation by the DNA polymerase of adenovirus type 2 requires nuclear factor I (NFI), a cellular sequence-specific transcription factor. Three functions of NFI--dimerization, DNA binding, and activation of DNA replication--are colocalized within the N-terminal portion of the protein. To define more precisely the role of NFI in viral DNA replication, a series of site-directed mutations within the N-terminal domain have been generated, thus allowing the separation of all three functions contained within this region. Impairment of the dimerization function prevents sequence-specific DNA binding and in turn abolishes the NFI-mediated activation of DNA replication. NFI DNA-binding activity, although necessary, is not sufficient to activate the initiation of adenovirus replication. A distinct class of NFI mutations that abolish the recruitment of the viral DNA polymerase to the origin also prevent the activation of replication. Thus, a direct interaction of NFI with the viral DNA polymerase complex is required to form a stable and active preinitiation complex on the origin and is responsible for the activation of replication by NFI.

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OBJECTIVE To assess the digital educational technology interface Caring for the sensory environment in the neonatal unit: noise, lighting and handling based on ergonomic criteria. METHODS Descriptive study, in which we used the guidelines and ergonomic criteria established by ISO 9241-11 and an online Likert scale instrument to identify problems and interface qualities. The instrument was built based on Ergolist, which follows the criteria of ISO 9141-11. There were 58 undergraduate study participants from the School of Nursing of Ribeirao Preto, University of Sao Paulo, who attended the classes about neonatal nursing content. RESULTS All items were positively evaluated by more than 70% of the sample. CONCLUSION Educational technology is appropriate according to the ergonomic criteria and can be made available for teaching nursing students.

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OBJECTIVE To investigate the concept understood by Family Healthcare Strategy (ESF) professionals of knowledge, education and subjects participating in learning activities. METHOD Qualitative study carried out with the ESF professionals with university degree, members of the healthcare staff who undertook educational health group activities at Basic Healthcare Units (UBS) in Belo Horizonte. The following triangulation techniques were used: participant observation, photos and field notes; interviews with professionals; and document analysis. RESULTS We identified three interaction patterns that are different from each other. Firstly, the professional questions, listens and provides information to users, trusting in the transmission of knowledge; secondly, the professional questions and listens, trusting that users can learn from each other; thirdly, the professional questions, listens, discusses and produces knowledge with users, both teaching and learning from each other. CONCLUSION There are educational practices that include unique methods capable of creating a militant space for citizenship engagement.

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In this paper we view bargaining and cooperation as an interaction superimposed on a strategic form game. A multistage bargaining procedure for N players, the proposer commitment procedure, is presented. It is inspired by Nash s two-player variable-threat model; a key feature is the commitment to threats. We establish links to classical cooperative game theory solutions, such as the Shapley value in the transferable utility case. However, we show that even in standard pure exchange economies the traditional coalitional function may not be adequate when utilities are not transferable.

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IL-2 is crucial to T cell homeostasis, especially of CD4(+) T regulatory cells and memory CD8(+) cells, as evidenced by vigorous proliferation of these cells in vivo following injections of superagonist IL-2/anti-IL-2 antibody complexes. The mechanism of IL-2/anti-IL-2 antibody complexes is unknown owing to a lack of understanding of IL-2 homeostasis. We show that IL-2 receptor alpha (CD25) plays a crucial role in IL-2 homeostasis. Thus, prolongation of IL-2 half-life and blocking of CD25 using antibodies or CD25-deficient mice led in combination, but not alone, to vigorous IL-2-mediated T cell proliferation, similar to IL-2/anti-IL-2 antibody complexes. These data suggest an unpredicted role for CD25 in IL-2 homeostasis.

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Objectives: The aim of this study was to compare specificity and sensitivity of different biological markers that can be used in a forensic field to identify potentially dangerous drivers because of their alcohol habits. Methods: We studied 280 Swiss drivers after driving while under the alcohol influence. 33 were excluded for not having CDT N results, 247 were included (218 men (88%) and 29 women (12%). Mean age was 42,4 (SD:12, min: 20 max: 76). The evaluation of the alcohol consumption concerned the month before the CDT test and was considered as such after the interview: Heavy drinkers (>3 drinks per day): 60 (32.7%), < 3 drinks per day and moderate: 127 (51.4%) 114 (46.5%), abstinent: 60 (24.3%) 51 (21%). Alcohol intake was monitored by structured interviews, self-reported drinking habits and the C-Audit questionnaire as well as information provided by their family and general practitioner. Consumption was quantified in terms of standard drinks, which contain approximately 10 grams of pure alcohol (Ref. WHO). Results: comparison between moderate (less or equal to 3 drinks per day) and excessive drinkers (more than 3 drinks) Marker ROC area 95% CI cut-off sensitivity specificity CDT TIA 0.852 0.786-0917 2.6* 0.93 LR+1.43 0.35 LR-0.192 CDT N latex 0.875 0.821-0.930 2.5* 0.66 LR+ 6.93 0.90 LR- 0.369 Asialo+disialo-tf 0.881 0.826-0.936 1.2* 0.78 LR+4.07 0.80 LR-0.268 1.7° 0.66 LR+8.9 0.93 LR-0.360 GGT 0.659 0.580-0.737 85* 0.37 LR+2.14 0.83 LR-0.764 * cut-off point suggested by the manufacturer ° cut-off point suggested by our laboratory Conclusion: With the cut-off point established by the manufacturer, CDT TIA performed poorly in term of specificity. N latex CDT and CZE CDT were better, especially if a 1.7 cut-off is used with CZE

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This paper presents an analysis of the credibility of the EMScurrencies that covers the period before and after the increase in thebands of fluctuation. Our credibility indicator is based on the inferredprobabilities derived from the estimation of a Markov-switching model(Hamilton (1989)) applied to the expected rate of depreciation. Theresults show that, for most of the currencies, credibility has improved,at least transitorily, after the increase in the bands. However, for allcurrencies, the credibility measured by the indicator proposed in thispaper has been eroded recently even with the widened bands.

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We characterize the Walrasian allocations correspondence by means offour axioms: consistency, replica invariance, individual rationality andPareto optimality. It is shown that for any given class of exchange economiesany solution that satisfies the axioms is a selection from the Walrasianallocations with slack. Preferences are assumed to be smooth, but may besatiated and non--convex. A class of economies is defined as all economieswhose agents' preferences belong to an arbitrary family (finite or infinite)of types. The result can be modified to characterize equal budget Walrasianallocations with slack by replacing individual rationality with individualrationality from equal division. The results are valid also for classes ofeconomies in which core--Walras equivalence does not hold.

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Models of the exchange process based on search theory can be usedto analyze the features of objects that make them more or less likely toemerge as ``money'' in equilibrium. These models illustrate the trade--offbetween endogenous acceptability (an equilibrium property) and intrinsiccharacteristics of goods, such as storability, recognizability, etc. Inthis paper, we look at how the relative supply and demand for various goodsaffect their likelihood of becoming money. Intuitively, goods in highdemand and/or low supply are more likely to appear as commodity money,subject to the qualification that which object ends up circulating as amedium of exchange depends at least partly on convention. Welfare propertiesare discussed.