La plus-value des images

La plus-value des images

FLUCTUATION AND LOW TRANSVERSE MOMENTUM CORRELATION RESULTS FROM PHENIX.

The PHENIX Experiment at the Relativistic Heavy Ion Collider has conducted a survey of fluctuations in charged hadron multiplicity in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 22, 62, and 200 GeV. A universal power law scaling for multiplicity fluctuations expressed as {sigma}{sup 2}/{mu}{sup 2} is observed as a function of N{sub part} for all species studied that is independent of the transverse momentum range of the measurement. PHENIX has also measured transverse momentum correlation amplitudes in p+p, d+Au, and Au+Au collisions. At low transverse momentum, significant differences in the correlations between the baseline p+p and d+Au data and the Au+Au data are presented

SCALING PROPERTIES OF FLUCTUATION RESULTS FROM THE PHENIX EXPERIMENT AT RHIC.

The PHENIX Experiment at the Relativistic Heavy Ion Collider has made measurements of event-by-event fluctuations in the charged particle multiplicity as a function of collision energy, centrality, collision species, and transverse momentum in several heavy ion collision systems. It is observed that the fluctuations in terms of {sigma}{sup 2}/{mu}{sup 2} exhibit a universal power-law scaling as a function of N{sub participants} that is independent of the transverse momentum range of the measurement

A framework for the local information dynamics of distributed computation in complex systems

The nature of distributed computation has often been described in terms of the component operations of universal computation: information storage, transfer and modification. We review the first complete framework that quantifies each of these individual information dynamics on a local scale within a system, and describes the manner in which they interact to create non-trivial computation where "the whole is greater than the sum of the parts". We describe the application of the framework to cellular automata, a simple yet powerful model of distributed computation. This is an important application, because the framework is the first to provide quantitative evidence for several important conjectures about distributed computation in cellular automata: that blinkers embody information storage, particles are information transfer agents, and particle collisions are information modification events. The framework is also shown to contrast the computations conducted by several well-known cellular automata, highlighting the importance of information coherence in complex computation. The results reviewed here provide important quantitative insights into the fundamental nature of distributed computation and the dynamics of complex systems, as well as impetus for the framework to be applied to the analysis and design of other systems.Comment: 44 pages, 8 figure

Pictorial turn. Una risposta

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Showing seeing uma crítica da cultura visual

Este ensaio tem como objetivo mapear as principais questões em torno dos estudos visuais como a sua recente transformação em um campo acadêmico, o seu conceito teórico ou objeto de pesquisa e ensino. Após um levantamento de algumas das resistências encontradas pelo estudos visuais em áreas como história da arte, estética e estudos de mídia, e considerando que os estudos visuais vem desempenhando o papel de “suplemento perigoso” para tais campos do saber; este ensaio reflete uma discussão sobre algumas das principais ideias que contribuem positiva ou negativamente para o campo dos estudos visuais. Falsas verdades ou mitos incluem noções de desmaterialização da imagem e do apagamento das fronteiras entre arte e não arte, entre comunicação visual e verbal. Incluem-se também falsas noções de que exista uma mídia exclusivamente visual. A aposta da crítica política do iconoclasta (por exemplo, a derrubada de “regimes escópicos”) também são questionadas, além da proposição de uma estratégia alternativa (Nietzschiana) de “reverberação dos ídolos”. O ensaio conclui com a descrição de estratégias pedagógicas no ensino da cultura visual, centradas em um exercício chamado pelo autor de “showing seeing”

Evidence from Cameroon reveals differences in the genetic structure and histories of chimpanzee populations

The history of the genus Pan is a topic of enduring interest. Chimpanzees (Pan troglodytes) are often divided into subspecies, but the population structure and genetic history of chimpanzees across Africa remain unclear. Some population genetics studies have led to speculation that, until recently, this species constituted a single population with ongoing gene flow across its range, which resulted in a continuous gradient of allele frequencies. Chimpanzees, designated here as P. t. ellioti, occupy the Gulf of Guinea region that spans southern Nigeria and western Cameroon at the center of the distribution of this species. Remarkably, few studies have included individuals from this region, hindering the examination of chimpanzee population structure across Africa. Here, we analyzed microsatellite genotypes of 94 chimpanzees, including 32 designated as P. t. ellioti. We find that chimpanzees fall into three major populations: (i) Upper Guinea in western Africa (P. t. verus); (ii) the Gulf of Guinea region (P. t. ellioti); and (iii) equatorial Africa (P. t. troglodytes and P. t. schweinfurthii). Importantly, the Gulf of Guinea population is significantly different genetically from the others, sharing a last common ancestor with the populations in Upper Guinea similar to 0.46 million years ago (mya) and equatorial Africa similar to 0.32 mya. Equatorial chimpanzees are subdivided into up to three populations occupying southern Cameroon, central Africa, and eastern Africa, which may have constituted a single population until similar to 0.10-0.11 mya. Finally, occasional hybridization may be occurring between the Gulf of Guinea and southern Cameroon population