L’Empire dans l’histoire britannique

De façon étonnante, l’histoire impériale était négligée dans la plupart des écoles et des universités britanniques, même quand l’Empire était à son apogée, et bien au-delà. Cependant, elle a connu une résurgence depuis les années 1980 : en partie pour des raisons politiques (le renouveau de l’« impérialisme » dans le monde, sous l’égide des États-Unis), et en partie en raison de l’influence de deux approches universitaires nouvelles : le « post-colonialisme » qui s’appuie surtout sur les « cultural studies », et la « nouvelle histoire impériale ». Il en a résulté une expansion considérable des aspects et des ramifications de l’impérialisme britannique que l’on étudie aujourd’hui, mais aussi l’émergence de nouveaux problèmes, sémantiques et théoriques en particulier. Ce renouveau ne semble pas avoir eu de conséquences sur une autre évolution, concomitante : certains auteurs à succès et même des hommes politiques travaillistes ont cherché à réhabiliterl’ancien Empire britannique, après des décennies de ce qu’ils considèrent avoir été une approche injuste.Imperial history was strangely neglected in most British schools and universities even during the period when the Empire was at its height, and well into post-imperial times. Since the 1980s, however, it has seen a resurgence; partly for political reasons – the perceived revival of “imperialism” in the world under the Americans – and partly though the influence of two new academic approaches: “Post-Colonialism”, which is mainly “Cultural Studies” based; and the “New Imperial History”. The result has been an enormous expansion of the range of aspects and ramifications of British imperialism now studied; but also the emergence of some new problems, especially semantic and theoretical. Running parallel with this, but seemingly unaffected by it, has been a new attempt on the part of certain popular writers and even Labour politicians to rehabilitate the old British Empire, after decades of – as they see it – unfair obloquy

Paul Laity, The British Peace Movement 1870-1914. Oxford,Clarendon Press; 2001. IX + 270 p. ISBN: 0 19 924835 4.

 « L’idée selon laquelle on pouvait abolir la guerre », dit Paul Laity dans ce livre, « a été plus répandue en Grande-Bretagne au XIXe siècle qu’au sein d’aucune autre puissance européenne. » C’est en premier lieu à cause de la sécurité géographique du pays, en raison de son insularité ; ensuite, l’in­fluence de la doctrine libre-échangiste, qui a toujours eu une forte composante pacifiste : les idéalistes du libéralisme comme Richard Cobden pensaient que quand les gens échangeraient libremen..

Peculiarities in the Spectrum of the Adjoint Scalar Kinetic Operator in Yang-Mills Theory

We study the spectrum of low-lying eigenmodes of the kinetic operator for scalar particles, in the color adjoint representation of Yang-Mills theory. The kinetic operator is the covariant Laplacian, plus a constant which serves to renormalize mass. In the pure gauge theory, our data indicates that the interval between the lowest eigenvalue and the mobility edge tends to infinity in the continuum limit. On these grounds, it is suggested that the perturbative expression for the scalar propagator may be misleading even at distance scales that are small compared to the confinement scale. We also measure the density of low-lying eigenmodes, and find a possible connection to multi-critical matrix models of order m=1.Comment: 9 pages, 14 figure

Organization of networks with tagged nodes and biased links: a priori distinct communities. The case of Intelligent Design Proponents and Darwinian Evolution Defenders

Among topics of opinion formation it is of interest to observe the characteristics of networks with a priori distinct communities. As an illustration, we report on the citation network(s) unfolded in the recent decades through web available works belonging to selected members of the Neocreationist and Intelligent Design Proponents (IDP) and the Darwinian Evolution Defenders (DED) communities. An adjacency matrix of tagged nodes is first constructed; it is not symmetric. A generalization of considerations pertaining to the case of networks with biased links, directed or undirected, is thus presented. The main characteristic coefficients describing the structure of such partially directed networks with tagged nodes are outlined. The structural features are discussed searching for statistical aspects, equivalence or not of subnetworks through the degree distributions, each network assortativity, the global and local clustering coefficients and the Average Overlap Indices. The various closed and open triangles made from nodes, moreover distinguishing the community, are especially listed to calculate the clustering characteristics. The distribution of elements in the rectangular submatrices are specially examined since they represent inter-community connexions. The emphasis being on distinguishing the number of vertices belonging to a given community. Using such informations one can distinguish between opinion leaders, followers and main rivals and briefly interpret their relationships through psychological-like conditions intrinsic to behavior rules in either community. Considerations on other controversy cases with similar social constraints are outlined, as well as suggestions on further, more general, work deduced from our observations on such networks.Comment: 40 pages, 61 references, 7 Tables, 11 Figures, 2 Appendices (giving the adjacency matrices

Reconstructing dynamical networks via feature ranking

Empirical data on real complex systems are becoming increasingly available. Parallel to this is the need for new methods of reconstructing (inferring) the topology of networks from time-resolved observations of their node-dynamics. The methods based on physical insights often rely on strong assumptions about the properties and dynamics of the scrutinized network. Here, we use the insights from machine learning to design a new method of network reconstruction that essentially makes no such assumptions. Specifically, we interpret the available trajectories (data) as features, and use two independent feature ranking approaches -- Random forest and RReliefF -- to rank the importance of each node for predicting the value of each other node, which yields the reconstructed adjacency matrix. We show that our method is fairly robust to coupling strength, system size, trajectory length and noise. We also find that the reconstruction quality strongly depends on the dynamical regime

Three-dimensional chemically homogeneous and bi-abundance photoionization models of the "super-metal-rich" planetary nebula NGC 6153

Deep spectroscopy of the planetary nebula (PN) NGC\,6153 shows that its heavy element abundances derived from optical recombination lines (ORLs) are ten times higher than those derived from collisionally excited lines (CELs), and points to the existence of H-deficient inclusions embedded in the diffuse nebula. In this study, we have constructed chemically homogeneous and bi-abundance three-dimensional photoionization models, using the Monte Carlo photoionization code {\sc mocassin}. We attempt to reproduce the multi-waveband spectroscopic and imaging observations of NGC\,6153, and investigate the nature and origin of the postulated H-deficient inclusions, as well as their impacts on the empirical nebular analyses assuming a uniform chemical composition. Our results show that chemically homogeneous models yield small electron temperature fluctuations and fail to reproduce the strengths of ORLs from C, N, O and Ne ions. In contrast, bi-abundance models incorporating a small amount of metal-rich inclusions ($\sim 1.3$ per cent of the total nebular mass) are able to match all the observations within the measurement uncertainties. The metal-rich clumps, cooled down to a very low temperature ($\sim 800$~K) by ionic infrared fine-structure lines, dominate the emission of heavy element ORLs, but contribute almost nil to the emission of most CELs. We find that the abundances of C, N, O and Ne derived empirically from CELs, assuming a uniform chemical composition, are about 30 per cent lower than the corresponding average values of the whole nebula, including the contribution from the H-deficient inclusions. Ironically, in the presence of H-deficient inclusions, the traditional standard analysis of the optical helium recombination lines, assuming a chemically homogeneous nebula, overestimates the helium abundance by 40 per cent.Comment: 19 pages, 18 figures, accepted for publication in MNRA

Abundances in planetary nebulae: NGC1535, NGC6629, He2-108, and Tc1

The aim of the paper is to determine abundances in a group of PNe with uniform morphology. The PNe discussed are circular excited by rather low-temperature central stars. The relation between abundance and evolution is discussed. The mid-infrared spectra of NGC1535, NGC6629, He2-108 and Tc1 taken with the Spitzer Space Telescope are presented. These spectra are combined with IUE and visual spectra to obtain complete extinction-corrected spectra from which the abundances are determined. These abundances are more accurate for several reasons, the most important is that the inclusion of the far infrared spectra increases the number of observed ions and makes it possible to include the nebular temperature gradient in the abundance calculation. The abundances of these PNe are compared to those found in five other PNe of similar properties and are further compared with predictions of evolutionary models. From this comparison we conclude that these PNe originated from low mass stars, probably between 1 and 2.5 solar masses and at present have core masses between 0.56 and 0.63 solar masses. A consistent description of the evolution of this class of PNe is found that agrees with the predictions of the present nebular abundances, the individual masses and the luminosities of these PNe. The distances to these nebulae can be found as well.Comment: 17 pages, 18 tables, 1 figure, Accepted for publication in A&