180,290 research outputs found
A Note on Sums of Powers
No full textWe improve a result of Bennett concerning certain sequences involving sums of powers
of positive integers
How to Measure Group Selection in Real-world Populations
No full textMultilevel selection and the evolution of cooperation are fundamental to the formation of higher-level organisation and the evolution of biocomplexity, but such notions are controversial and poorly understood in natural populations. The theoretic principles of group selection are well developed in idealised models where a population is neatly divided into multiple semi-isolated sub-populations. But since such models can be explained by individual selection given the localised frequency-dependent effects involved, some argue that the group selection concepts offered are, even in the idealised case, redundant and that in natural conditions where groups are not well-defined that a group selection framework is entirely inapplicable. This does not necessarily mean, however, that a natural population is not subject to some interesting localised frequency-dependent effects – but how could we formally quantify this under realistic conditions? Here we focus on the presence of a Simpson’s Paradox where, although the local proportion of cooperators decreases at all locations, the global proportion of cooperators increases. We illustrate this principle in a simple individual-based model of bacterial biofilm growth and discuss various complicating factors in moving from theory to practice of measuring group selection
Frank Ramsey: A Sheer Excess of Powers
Full text linkLe mathématicien et philosophe Frank Ramsey est décédé le 19 janvier 1930, à l’aube de ses 27 ans, vraisemblablement après avoir contracté une infection en se baignant dans la rivière Cam. Pour les gens, comme lui, dont le génie est évident, une mort précoce est susceptible de mener à l’élaboration d’un mythe autour de leur vie et de leur œuvre. Comme le souligne judicieusement l’auteure, les intellectuels ont, eux aussi, besoin de héros.
Cheryl Misak a fait œuvre utile en produisant la première biographie de Frank Ramsey qui est à la fois complète et détaillée
Empire, Hegemony, and Leadership: Developing a Research Framework for the Study of Regional Powers
Full text linkRegional powers are often conceived of as “regional leading powers,” states which adopt a cooperative and benevolent attitude in their international relations with their neighbors. The paper argues that regional powers can follow a much wider range of foreign policy strategies in their region. Three ideal-typical regional strategies are identified: empire, hegemony, and leadership. The paper is devoted to a theory-led distinction and clarification of these three terms, which are often used interchangeably in the field of international relations. According to the goals pursued, to the means employed, and to other discriminating features such as the degree of legitimation and the type of self-representation by the dominant state, the paper outlines the essential traits of imperial, hegemonic, and leading strategies and identifies subtypes for better classifying hegemony and leadership.regional powers, empire, hegemony, leadership, strategy
Social niche construction: evolutionary explanations for cooperative group formation
No full textCooperative behaviours can be defined as those that benefit others at an apparent cost to self. How these kinds of behaviours can evolve has been a topic of great interest in evolutionary biology, for at first sight we would not expect one organism to evolve to help another. Explanations for cooperation rely on the presence of a population structure that clusters cooperators together, such that they enjoy the benefits of each others' actions. But, the question that has been left largely unaddressed is, how does this structure itself evolve? If we want to really explain why organisms cooperate, then we need to explain not just their adaptation to their social environment, but why they live in that environment.It is well-known that individual genetic traits can affect population structure; an example is extracellular matrix production by bacteria in a biofilm. Yet, the concurrent evolution of such traits with social behaviour is very rarely considered. We show here that social behaviour can exert indirect selection pressure on population structure-modifying traits, causing individuals to adaptively modify their population structure to support greater cooperation. Moreover, we argue that any component of selection on structure modifying traits that is due to social behaviour must be in the direction of increased cooperation; that component of selection cannot be in favour of the conditions for greater selfishness. We then examine the conditions under which this component of selection on population structure exists. Thus, we argue that not only can population structure drive the evolution of cooperation, as in classical models, but that the benefits of greater cooperation can in turn drive the evolution of population structure - a positive feedback process that we call social niche construction.We argue that this process is necessary in providing an adaptive explanation for some of the major transitions in evolution (such as from single- to multi- celled organisms, and from solitary insects to eusocial colonies). Any satisfactory account of these transitions must explain how the individuals came to live in a population structure that supported high degrees of cooperation, as well as showing that cooperation is individually advantageous given that structure
Fractional powers and singular perturbations of quantum differential Hamiltonians
No full textWe consider the fractional powers of singular (point-like) perturbations of the Laplacian and the singular perturbations of fractional powers of the Laplacian, and we compare two such constructions focusing on their perturbative structure for resolvents and on the local singularity structure of their domains. In application to the linear and non-linear Schrodinger equations for the corresponding operators, we outline a programme of relevant questions that deserve being investigated. Published by AIP Publishing
Fictionalising music / musicalising fiction: the integrative function of music in Richard Powers' The Time of Our Singing
Full text linkTwentieth-century scholars tended to describe music either in constructivist terms, as a culturally produced system of signs without real effects, or in essentialist terms, as a universal force detached from sociocultural contexts. Recently, however, the field of sound studies has raised new awareness of the fact that music is, at its core, sound. It is thus both culturally constructed and ineluctably material. Given this shift in the scholarly conception of music, a reassessment of its functions is needed. Starting from the notion that music is a complex system of cultural meanings and concrete sounds, this article investigates its integrative function, that is, the notion that music is able to connect individuals from diverse backgrounds and to integrate them into a community. Richard Powers’ novel The Time of Our Singing (2003) provides a valuable platform for reassessing the integrative function of music, as it unfolds it on two different levels at the same time. On its narrative level the novel insists on the long-term failure of music in uniting people from different racial backgrounds. Yet, by being also a piece of musicalised fiction and, hence, musical itself, the novel tests this function on its aesthetic level as well. It thus shows that, while failing to integrate socially divided people in the long run, in its aesthetic experience, at least, music is able to bring them together for as long as the performance lasts
Pavlovian conditioning–induced hallucinations result from overweighting of perceptual priors
Full text linkSome people hear voices that others do not, but only some of those people seek treatment. Using a Pavlovian learning task, we induced conditioned hallucinations in four groups of people who differed orthogonally in their voice-hearing and treatment-seeking statuses. People who hear voices were significantly more susceptible to the effect. Using functional neuroimaging and computational modeling of perception, we identified processes that differentiated voice-hearers from non-voice-hearers and treatment-seekers from non-treatment-seekers and characterized a brain circuit that mediated the conditioned hallucinations. These data demonstrate the profound and sometimes pathological impact of top-down cognitive processes on perception and may represent an objective means to discern people with a need for treatment from those without
Rising Powers and State Transformation: The Case of China
Full text linkThis article draws attention to the transformation of statehood under globalisation as a crucial dynamic shaping the emergence and conduct of ‘rising powers’. That states are becoming increasingly fragmented, decentralised and internationalised is noted by some international political economy and global governance scholars, but is neglected in International Relations treatments of rising powers. This article critiques this neglect, demonstrating the importance of state transformation in understanding emerging powers’ foreign and security policies, and their attempts to manage their increasingly transnational interests by promoting state transformation elsewhere, particularly in their near-abroad. It demonstrates the argument using the case of China, typically understood as a classical ‘Westphalian’ state. In reality, the Chinese state’s substantial disaggregation profoundly shapes its external conduct in overseas development assistance and conflict zones like the South China Sea, and in its promotion of extraterritorial governance arrangements in spaces like the Greater Mekong Subregion
Paul and the powers in relation to Christ's supremacy:: re-visiting the Pauline concept of "supernatural powers" from an African worldview perspective.
Full text linkThe Pauline concept of "supernatural powers" underlines the supremacy of Christ over "supernatural powers". They were created in him, through him and for him (Col 1: 16-20). Christ's death was not only their defeat, but also their humiliation (Col 2: 15). Christ's resurrection and exaltation clearly speaks of his supremacy (Eph 1: 20f; Phil 2: 9-11). Christ is also supreme since "supernatural powers" cannot separate believers from the love of God (Rom 8: 38f) or thwart the existence of the church, through which the manifold wisdom of God is made known to them (Eph 3: 10). Paul's teachings about the "powers" in relation to Christ's supremacy do not seem to have had much sway in the African context. This happens due to two opposite but related errors: that of believing "supernatural powers" exist and allowing them to determine human existence and that of denying they exist. Yet the Pauline concept neither denies the existence of "supernatural powers" nor allows them to be given allegiance or worship as if they are equal to Christ. Due to these two errors, which also represent the missionary legacy and the African response to it, most African believers hold a dual religious heritage that causes pastoral problems for the African church. Rather than engaging the dual religious heritage, most of the studies on "supernatural powers" seem to have complicated it. The trend among anthropologists has been to deny that "supernatural powers" exists and/or to reduce them to psychological or social or political or religious functions. Several biblical scholars, who deal with "supernatural powers" from the perspective of myth, maintain that "supernatural powers" were marginal in Paul's thinking and irrelevant for modern Christians. They maintain that Paul demythologised "supernatural powers" so as to refer to existential realities such as sin and death or to the structures of human existence. As a result, most of the anthropological and biblical treatises on "supernatural powers" do not seem to engage the full measure of the African beliefs in "supernatural powers". This is largely because their interpretations of "supernatural powers" are shaped by the Western worldview and are mainly from a Western worldview perspective. But the interpretation of reality as people perceives it is usually shaped by their worldview. For that reason, it is vital to re-visit the Pauline concept of "supernatural powers" from an African worldview perspective, taking into consideration that Paul initially spoke to a context similar to the African context with regard to the beliefs in, and fear of "supernatural powers"
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