45 resultados para Ambiguity
Resumo:
This paper finds preference reversals in measurements of ambiguity aversion, even if psychological and informational circumstances are kept constant. The reversals are of a fundamentally different nature than the reversals found before because they cannot be explained by context-dependent weightings of attributes. We offer an explanation based on Sugden's random-reference theory, with different elicitation methods generating different random reference points. Then measurements of ambiguity aversion that use willingness to pay are confounded by loss aversion and hence overestimate ambiguity aversion.
Resumo:
We propose a novel method for scoring the accuracy of protein binding site predictions – the Binding-site Distance Test (BDT) score. Recently, the Matthews Correlation Coefficient (MCC) has been used to evaluate binding site predictions, both by developers of new methods and by the assessors for the community wide prediction experiment – CASP8. Whilst being a rigorous scoring method, the MCC does not take into account the actual 3D location of the predicted residues from the observed binding site. Thus, an incorrectly predicted site that is nevertheless close to the observed binding site will obtain an identical score to the same number of nonbinding residues predicted at random. The MCC is somewhat affected by the subjectivity of determining observed binding residues and the ambiguity of choosing distance cutoffs. By contrast the BDT method produces continuous scores ranging between 0 and 1, relating to the distance between the predicted and observed residues. Residues predicted close to the binding site will score higher than those more distant, providing a better reflection of the true accuracy of predictions. The CASP8 function predictions were evaluated using both the MCC and BDT methods and the scores were compared. The BDT was found to strongly correlate with the MCC scores whilst also being less susceptible to the subjectivity of defining binding residues. We therefore suggest that this new simple score is a potentially more robust method for future evaluations of protein-ligand binding site predictions.
Resumo:
Competitive Dialogue (CD) is a new contract award procedure of the European Community (EC). It is set out in Article 29 of the 'Public Sector Directive' 2004/18/EC. Over the last decades, projects were becoming more and more complex, and the existing EC procedures were no longer suitable to procure those projects. The call for a new procedure resulted in CD. This paper describes how the Directive has been implemented into the laws of two member states: the UK and the Netherlands. In order to implement the Directive, both lawmakers have set up a new and distinct piece of legislation. In each case, large parts of the Directive’s content have been repeated ‘word for word’; only minor parts have been reworded and/or restructured. In the next part of the paper, the CD procedure is examined in different respects. First, an overview is given on the different EC contract award procedures (open, restricted, negotiated, CD) and awarding methods (lowest price and Most Economically Advantageous Tender, MEAT). Second, the applicability of CD is described: Among other limitations, CD can only be applied to public contracts for works, supplies, and services, and this scope of application is further restricted by the exclusion of certain contract types. One such exclusion concerns services concessions. This means that PPP contracts which are set up as services concessions cannot be awarded by CD. The last two parts of the paper pertain to the main features of the CD procedure – from ‘contract notice’ to ‘contract award’ – and the advantages and disadvantages of the procedure. One advantage is that the dialogue allows the complexity of the project to be disentangled and clarified. Other advantages are the stimulation of innovation and creativity. These advantages are set against the procedure’s disadvantages, which include high transaction costs and a perceived hindrance of innovation (due to an ambiguity between transparency and fair competition). It is concluded that all advantages and disadvantages are related to one of three elements: communication, competition, and/or structure of the procedure. Further research is needed to find out how these elements are related.
Resumo:
Alterations to the genetic code – codon reassignments – have occurred many times in life’s history, despite the fact that genomes are coadapted to their genetic codes and therefore alterations are likely to be maladaptive. A potential mechanism for adaptive codon reassignment, which could trigger either a temporary period of codon ambiguity or a permanent genetic code change, is the reactivation of a pseudogene by a nonsense suppressor mutant transfer RNA. I examine the population genetics of each stage of this process and find that pseudogene rescue is plausible and also readily explains some features of extant variability in genetic codes.
Resumo:
Background: Biases in the interpretation of ambiguous material are central to cognitive models of anxiety; however, understanding of the association between interpretation and anxiety in childhood is limited. To address this, a prospective investigation of the stability and specificity of anxious cognitions and anxiety and the relationship between these factors was conducted. Method: Sixty-five children (10–11 years) from a community sample completed measures of self-reported anxiety, depression, and conduct problems, and responded to ambiguous stories at three time points over one-year. Results: Individual differences in biases in interpretation of ambiguity (specifically “anticipated distress” and “threat interpretation”) were stable over time. Furthermore, anticipated distress and threat interpretation were specifically associated with anxiety symptoms. Distress anticipation predicted change in anxiety symptoms over time. In contrast, anxiety scores predicted change in threat interpretation over time. Conclusions: The results suggest that different cognitive constructs may show different longitudinal links with anxiety. These preliminary findings extend research and theory on anxious cognitions and their link with anxiety in children, and suggest that these cognitive processes may be valuable targets for assessment and intervention.
Resumo:
Aircraft Maintenance, Repair and Overhaul (MRO) feedback commonly includes an engineer’s complex text-based inspection report. Capturing and normalizing the content of these textual descriptions is vital to cost and quality benchmarking, and provides information to facilitate continuous improvement of MRO process and analytics. As data analysis and mining tools requires highly normalized data, raw textual data is inadequate. This paper offers a textual-mining solution to efficiently analyse bulk textual feedback data. Despite replacement of the same parts and/or sub-parts, the actual service cost for the same repair is often distinctly different from similar previously jobs. Regular expression algorithms were incorporated with an aircraft MRO glossary dictionary in order to help provide additional information concerning the reason for cost variation. Professional terms and conventions were included within the dictionary to avoid ambiguity and improve the outcome of the result. Testing results show that most descriptive inspection reports can be appropriately interpreted, allowing extraction of highly normalized data. This additional normalized data strongly supports data analysis and data mining, whilst also increasing the accuracy of future quotation costing. This solution has been effectively used by a large aircraft MRO agency with positive results.
Resumo:
Stereoscopic white-light imaging of a large portion of the inner heliosphere has been used to track interplanetary coronal mass ejections. At large elongations from the Sun, the white-light brightness depends on both the local electron density and the efficiency of the Thomson-scattering process. To quantify the effects of the Thomson-scattering geometry, we study an interplanetary shock using forward magnetohydrodynamic simulation and synthetic white-light imaging. Identifiable as an inclined streak of enhanced brightness in a time–elongation map, the travelling shock can be readily imaged by an observer located within a wide range of longitudes in the ecliptic. Different parts of the shock front contribute to the imaged brightness pattern viewed by observers at different longitudes. Moreover, even for an observer located at a fixed longitude, a different part of the shock front will contribute to the imaged brightness at any given time. The observed brightness within each imaging pixel results from a weighted integral along its corresponding ray-path. It is possible to infer the longitudinal location of the shock from the brightness pattern in an optical sky map, based on the east–west asymmetry in its brightness and degree of polarisation. Therefore, measurement of the interplanetary polarised brightness could significantly reduce the ambiguity in performing three-dimensional reconstruction of local electron density from white-light imaging.
Resumo:
Serological typing of Escherichia coli O antigens is a well-established method used for differentiation and identification of O serotypes commonly associated with disease. In this feasibility study, we have developed a novel somatic antibody-based miniaturized microarray chip, using 17 antisera, which can be used to detect bound whole-cell E. coli antigen with its corresponding immobilized antibody, to assess the feasibility of this approach. The chip was tested using the related 17 control strains, and the O types found by the microarray chip showed 100% correlation with the O types found by conventional typing. A blind trial was performed in which 100 E. coli isolates that had been O serotyped previously by the conventional assay were tested by the array approach. Overall, the O serotypes of 88% of isolates were correctly identified by the microarray method. For several isolates, ambiguity of O-type designation by microarray arose due to increased sensitivity of this method, allowing signal intensities of cross-reactions to be quantified. Investigation of discrepancies between conventional and microarray O serotyping indicated that some isolates upon storage had become untypeable and, therefore, gave poor signal intensity when tested by the microarray or retested by conventional means. For all 20 serotype O26 and O157 isolates, the apparent discrepancy in O serotyping was analyzed further by a third independent test, which confirmed the microarray results. Therefore, the use of miniaturized protein arrays increases the speed and efficiency of O serotyping in a cost-effective manner, and these preliminary findings suggest the microarray approach may have a higher accuracy than those of traditional O-serotyping methods.
Resumo:
Purpose The article examines principles of Fair Trade in public procurement in Europe, focusing on legal dimensions related to the European Public Procurement Directives. Design/methodology/approach The article situates public procurement of Fair Trade products in relation to the rise of non-state regulatory initiatives, highlighting how they have entered into new governance dynamics in the public sector and play a part in changing practices in sustainable procurement. A review of legal position on Fair Trade in procurement law is informed by academic research and campaigning experience from the Fair Trade Advocacy Office. Findings Key findings are that the introduction of Fair Trade products into European public procurement has been marked by legal ambiguity, having developed outside comprehensive policy or legal guidelines. Following a 2012 ruling by the Court of Justice of the European Union, it is suggested that the legal position for Fair Trade in procurement has become clearer, and that forthcoming change to the Public Procurement Directives may facilitate the uptake of fair trade products by public authorities. However potential for future expansion of the public sector ‘market’ for Fair Trade is approached with caution: purchasing Fair Trade products as a marker of sustainability, which started to be embedded within procurement practice in the 2000s, is challenged by current European public austerity measures. Research limitations/implications Suggestions for future research include the need for systematic cross-institutional and multi-country comparison of the legal and governance dimensions of procurement practice with regard to Fair Trade. Practical implications A clarification of current state-of-play with regard to legal aspects of fair trade in public procurement of utility for policy and advocacy discussion. Originality/value The article provides needed elaboration on an under researched topic area of value to academia and policy makers.
Resumo:
This article discusses the literary relationship of the novelist and memoirist,Anne Thackeray Ritchie (1837–1919), and her step-niece, Virginia Woolf.Ritchie’s influence was a highly significant one which prompted a powerful ambiguity in Woolf, who was alternately admiring and dismissively anxious to deny influence, eager to relegate her to a staunchly Victorian past while covertly sensitive to those elements in her writing linking her with Modernism. These ‘Modern’ elements, including emphasis on the subjective nature of reality and the everyday life of the mind, occur in Ritchie’s fiction, affecting its style and structure. This article focuses on Night and Day, then on Woolf ’s more direct comments about Ritchie in diaries, letters and essays, comparing these comments and Woolf ’s theoretical agenda in defining Modernism and, implicitly, her own place in it. It also considers some of Ritchie’s fiction, with particular attention to two novellas, one a source for To The Lighthouse.
Resumo:
Perfectionism is a transdiagnostic construct associated with a range of diagnoses, including depression, eating disorders and obsessive compulsive disorder. Treatments that directly target perfectionist cognitions have been shown to successfully reduce associated pathologies. However, the way in which they do this is not clear. We set out to assess the role of one candidate mechanism of action, namely the cognitive process of interpretation of ambiguity. In one experiment we looked for associations between biased interpretation and perfectionism. In a second, we manipulated interpretations, thereby providing a strong test of their aetiological significance. Results from the first experiment confirmed the presence of biased interpretation in perfectionism and demonstrated that these are highly specific to perfection relevant information, rather than reflecting general negativity. The second experiment succeeded in manipulating these perfection relevant interpretations and demonstrated that one consequence of doing so is a change in perfectionist behaviour. Together, these data experimentally demonstrate that biased interpretation of perfection relevant ambiguity contributes to the maintenance of perfectionism, but that it is also possible to reverse this. Clinical implications include the identification of one likely mechanism of therapeutic change within existing treatments, as well as identification of an appropriate evidence based focus for future treatment development. Targeting underlying functional mechanisms, such as biased interpretation, has the potential to offer transdiagnostic benefits.
Resumo:
Although Richard Hooker’s private attitudes were clericalist and authoritarian, his constitutional theory subordinated clergymen to laymen and monarchy to parliamentary statute. This article explains why his political ideas were nonetheless appropriate to his presumed religious purposes. It notes a very intimate connection between his teleological conception of a law and his hostility towards conventional high Calvinist ideas about predestination. The most significant anomaly within his broadly Aristotelian world-view was his belief that politics is nothing but a means to cope with sin. This too can be linked to his religious ends, but it creates an ambiguity that made his doctrines usable by Locke.
Resumo:
The concept of a slowest invariant manifold is investigated for the five-component model of Lorenz under conservative dynamics. It is shown that Lorenz's model is a two-degree-of-freedom canonical Hamiltonian system, consisting of a nonlinear vorticity-triad oscillator coupled to a linear gravity wave oscillator, whose solutions consist of regular and chaotic orbits. When either the Rossby number or the rotational Froude number is small, there is a formal separation of timescales, and one can speak of fast and slow motion. In the same regime, the coupling is weak, and the Kolmogorov–Arnold-Moser theorem is shown to apply. The chaotic orbits are inherently unbalanced and are confined to regions sandwiched between invariant tori consisting of quasi-periodic regular orbits. The regular orbits generally contain free fast motion, but a slowest invariant manifold may be geometrically defined as the set of all slow cores of invariant tori (defined by zero fast action) that are smoothly related to such cores in the uncoupled system. This slowest invariant manifold is not global; in fact, its structure is fractal; but it is of nearly full measure in the limit of weak coupling. It is also nonlinearly stable. As the coupling increases, the slowest invariant manifold shrinks until it disappears altogether. The results clarify previous definitions of a slowest invariant manifold and highlight the ambiguity in the definition of “slowness.” An asymptotic procedure, analogous to standard initialization techniques, is found to yield nonzero free fast motion even when the core solutions contain none. A hierarchy of Hamiltonian balanced models preserving the symmetries in the original low-order model is formulated; these models are compared with classic balanced models, asymptotically initialized solutions of the full system and the slowest invariant manifold defined by the core solutions. The analysis suggests that for sufficiently small Rossby or rotational Froude numbers, a stable slowest invariant manifold can be defined for this system, which has zero free gravity wave activity, but it cannot be defined everywhere. The implications of the results for more complex systems are discussed.
Resumo:
In this paper we provide an alternative explanation for why illegal immigration can exhibit substantial fluctuation. We develop a model economy in which migrants make decisions in the face of uncertain border enforcement and lump-sum transfers from the host country. The uncertainty is extrinsic in nature, a sunspot, and arises as a result of ambiguity regarding the commodity price of money. Migrants are restricted from participating in state-contingent insurance markets in the host country, whereas host country natives are not. Volatility in migration flows stems from two distinct sources: the tension between transfers inducing migration and enforcement discouraging it and secondly the existence of a sunspot. Finally, we examine the impact of a change in tax/transfer policies by the government on migration.
Resumo:
We present the first empirical study to reveal the presence of implicit discrimination in a non-experimental setting. By using a large dataset of in-match data in the English Premier League, we show that white referees award significantly more yellow cards against non-white players of oppositional identity. We argue that this is the result of implicit discrimination by showing that this discriminatory behaviour: (i) increases in how rushed the referee is before making a decision, and (ii) it increases in the level of ambiguity of the decision. The variation in (i) and (ii) cannot be explained by any form of conscious discrimination such as taste-based or statistical discrimination. Moreover, we show that oppositional identity players do not differ in their behaviour from other players along several dimensions related to aggressiveness and style of play providing further evidence that this is not statistical discrimination.