876 resultados para Almost Convergence


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In spite of the controversy that they have generated, neutral models provide ecologists with powerful tools for creating dynamic predictions about beta-diversity in ecological communities. Ecologists can achieve an understanding of the assembly rules operating in nature by noting when and how these predictions are met or not met. This is particularly valuable for those groups of organisms that are challenging to study under natural conditions (e.g., bacteria and fungi). Here, we focused on arbuscular mycorrhizal fungal (AMF) communities and performed an extensive literature search that allowed us to synthesize the information in 19 data sets with the minimal requisites for creating a null hypothesis in terms of community dissimilarity expected under neutral dynamics. In order to achieve this task, we calculated the first estimates of neutral parameters for several AMF communities from different ecosystems. Communities were shown either to be consistent with neutrality or to diverge or converge with respect to the levels of compositional dissimilarity expected under neutrality. These data support the hypothesis that divergence occurs in systems where the effect of limited dispersal is overwhelmed by anthropogenic disturbance or extreme biological and environmental heterogeneity, whereas communities converge when systems have the potential for niche divergence within a relatively homogeneous set of environmental conditions. Regarding the study cases that were consistent with neutrality, the sampling designs employed may have covered relatively homogeneous environments in which the effects of dispersal limitation overwhelmed minor differences among AMF taxa that would lead to environmental filtering. Using neutral models we showed for the first time for a soil microbial group the conditions under which different assembly processes may determine different patterns of beta-diversity. Our synthesis is an important step showing how the application of general ecological theories to a model microbial taxon has the potential to shed light on the assembly and ecological dynamics of communities.

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Discusses the amendments to the Polish Competition Act 2007 adopted in June 2014 which aim to enhance the effectiveness of antitrust enforcement, including the introduction of: (1) civil fines for individuals; (2) a "leniency plus" programme based on the US model; (3) a settlement procedure; and (4) extended inspection powers for the Competition Authority. Assesses the likely effectiveness of the reforms.

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The momentum term has long been used in machine learning algorithms, especially back-propagation, to improve their speed of convergence. In this paper, we derive an expression to prove the O(1/k2) convergence rate of the online gradient method, with momentum type updates, when the individual gradients are constrained by a growth condition. We then apply these type of updates to video background modelling by using it in the update equations of the Region-based Mixture of Gaussians algorithm. Extensive evaluations are performed on both simulated data, as well as challenging real world scenarios with dynamic backgrounds, to show that these regularised updates help the mixtures converge faster than the conventional approach and consequently improve the algorithm’s performance.

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Motivated by the description of the C*-algebra of the affine automorphism group N6,28 of the Siegel upper half-plane of degree 2 as an algebra of operator fields defined over the unitary dual View the MathML source of the group, we introduce a family of C*-algebras, which we call almost C0(K), and we show that the C*-algebra of the group N6,28 belongs to this class.

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We consider in this paper the family of exponential Lie groups Gn,µ, whose Lie algebra is an extension of the Heisenberg Lie algebra by the reals and whose quotient group by the centre of the Heisenberg group is an ax + b-like group. The C*-algebras of the groups Gn,µ give new examples of almost C0(K)-C*-algebras.

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This paper argues that the modern barn in Ireland is a complex social and architectural phenomena that is without, or has yet to find, a satisfactory discourse. Emerging in the middle third of the twentieth century, the modern barn – replete with corrugated iron and I-sections – continues to represent a presence in the Irish landscape whose ubiquity is as emphatic as its flexibility. It is, however, its universal properties that begin to suggest connections with wider narratives. The modernising aspects of the barn that appear in the 1920s and 30s begin to conflate with a rhetoric of architectural modernism which was simultaneously appearing across Europe. But while the relationship between high modernism’s critique of what it divined as the inspirational qualities of utilitarian buildings – Walter Gropius on grain silos, Le Corbusier on aircraft hangers etc. – has been well-documented, in Ireland this relationship perhaps contains another layer of complexity.
The barn’s consolidation as a modern type coincided with the search for a nation’s cultural identity after centuries of colonial rule. This tended to be an introspective vision that prioritised rural space over urban space, agriculture over industry, and imagined the small farm as a central tenet in the construction of a new State. This paper suggests that the twentieth-century barn – as a product of the mechanisation of agriculture promoted by the new administrations – is an iconic structure, emblematic of attempts to reconcile the contradictory forces and imagery of modernity with the mores of a traditional society. Moreover, given a cultural purview that was often ambivalent or even hostile to the ideologies and forms of modernity, the barn in Ireland is, perhaps, not so much the inspiration but the realisation of an architectural modernism in that country at its most pervasive, enduring and unself-conscious.

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Yttrium triflate or triflic acid catalysed Povarov reaction of methyl anthranilate with ethyl vinyl ether, both as aldehyde surrogate and as alkene, gave the desired 2-methyl-4-ethoxytetrahydroquinoline diastereoisomers as the major products along with four component coupling von Miller adducts. A proton NMR-study, using yttrium triflate as catalyst, revealed that the cis-diastereoisomers were the initial major products in both the Povarov and von Miller reactions but that these isomerised to the trans-diastereoisomers under the reaction conditions. Two distinct pathways for forming von Miller adducts were uncovered with the initial Povarov products being converted to von Miller adducts under the reaction conditions. Replacement of the 4-ethoxy with a 4-methoxy group under acidic conditions gave predominantly the trans-diastereoisomer, which was subsequently converted to a cis/trans mixture of the tetrahydroquinoline antibiotic helquinoline. It was also possible to convert the von Miller products to Povarov products under acidic conditions

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Death of a spouse is associated with increased mortality risk for the surviving partner (the widowhood effect). We investigated whether the effect magnitude varied between urban, rural and intermediate areas, assembling death records (2001-2009) for a prospective cohort of 296,125 married couples in Northern Ireland. The effect was greatest during the first six months of widowhood in all areas and for both sexes. Subsequently, the effect was attenuated among men in rural and intermediate areas but persisted in urban areas (HRs and 95% CIs: rural 1.09 [0.99, 1.21]; urban 1.35 [1.26, 1.44]). Among women the effect was attenuated in all areas (rural 1.06 [0.96, 1.17]; urban 1.09 [1.01, 1.17]). The impacts of spousal bereavement varied between urban and more rural areas, possibly due to variation in social support provided by the wider community. We identify men in urban areas as being in greatest need of such support and a possible target for health interventions.

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Relations between Laplacian eigenvectors and eigenvalues and the existence of almost equitable partitions (which are generalizations of equitable partitions) are presented. Furthermore, on the basis of some properties of the adjacency eigenvectors of a graph, a necessary and sufficient condition for the graph to be primitive strongly regular is introduced. © 2006 Elsevier Ltd. All rights reserved.

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LivingTV's flagship series, Most Haunted, has been haunting the satellite network since 2002. The set-up of the series is straightforward: a team of investigators, including a historian, a parapsychologist, and "spiritualist medium" Derek Acorah, "legend-trip," spending the night at some location within the United Kingdom that is reputed to be haunted, with the hopes of catching on video concrete proof of the existence of ghosts. However, unlike other reality television or true-life supernatural television shows, Most Haunted includes and addresses the audience less as a spectator and more as an active participant in the ghost hunt. Watching Most Haunted, we are directed not so much to accept or reject the evidence provided, as to engage in the debate over the evidence's veracity. Like legend-telling in its oral form, belief in or rejection of the truth-claims of the story are less central than the possibility of the narrative's truth - a position that invites debates about those truth-claims. This paper argues that Most Haunted, in its premise and structure, not only depicts or represents legend texts (here ghost stories), but engages the audience in the debates about the status of its truth-claims, thereby bringing this mass-mediated popular culture text closer to the folkloristic, legend-telling dynamic than other similar shows.

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The I/Q mismatches in quadrature radio receivers results in finite and usually insufficient image rejection, degrading the performance greatly. In this paper we present a detailed analysis of the Blind-Source Separation (BSS) based mismatch corrector in terms of its structure, convergence and performance. The results indicate that the mismatch can be effectively compensated during the normal operation as well as in the rapidly changing environments. Since the compensation is carried out before any modulation specific processing, the proposed method works with all standard modulation formats and is amenable to low-power implementations.

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Online chatbots (also known as pedagogical agents or virtual assistants) are becoming embedded into the fabric of technology, both in educational and commercial settings. Yet understanding of these technologies is inchoate and often untheorised, influenced by individuals’ willingness to trust technologies, aesthetic appearance of the chatbot and technical literacy, among other factors. This paper draws upon data from two research studies that evaluated students’ experiences of using pedagogical agents in education using responsive evaluation. The findings suggest that emotional connections with pedagogical agents were intrinsic to the user’s sense of trust and therefore likely to affect levels of truthfulness and engagement. They also indicate that the topic of the pedagogical agent-student interaction is key to the student’s experience. The implications of these studies are that truthfulness, personalisation and emotional engagement are all vital components in using pedagogical agents to enhance online learning.

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Cappadocian Greek is reported to display agglutinative inflection in its nominal system, namely, mono-exponential formatives for the marking of case and number, and NOM.SG-looking forms as the morphemic units to which inflection applies. Previous scholarship has interpreted these developments as indicating a shift in morphological type from fusion to agglutination, brought about by contact with Turkish. This study takes issue with these conclusions. By casting a wider net over the inflectional system of the language, it shows that, of the two types of agglutinative formations identified, only one evidences a radical departure from the inherited structural properties of Cappadocian noun inflection. The other, on the contrary, represents a typologically more conservative innovation. The study presents evidence that a combination of system-internal and -external motivations triggered the development of both types, it describes the mechanisms through which the innovation was implemented, and discusses the factors that favoured change.

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The renowned writer J. B. Priestley suggested in 1934 that the motor-coach had annihilated the old distinction between rich and poor passengers in Britain. This article considers how true this was by examining the relationship between charabancs, motor coaches and class. It shows that this important vehicle of inter-war working class mobility had a complicated relationship with class, identifying three distinct forms of this method of travel. It positions the charabanc alongside historical responses to unwelcome steamer and railway day-trippers, and examines how resorts provided separate class-based entertainment for these holidaymakers. Using the case study of a new charabancwelcoming pub, the Prospect Inn, it proposes that, in the late 1930s, some pubs were beginning to offer charabanc customers facilities that were almost the match of their middle class equivalent. Motor coaches and charabancs contributed to the process of social convergence in inter-war Britain.