The future (?) of effective protection

This paper aims at a comparative reading of some archaeological remains in the island of Sardinia, starting from a reflection on the UNESCO discipline, which introduces a hierarchy of cultural heritage based on the level of worthiness of protection and provides enhanced protection for the goods that are on its list. The main goal of the study is to investigate in parallel the application of this ‘selective appreciation’ on the actual context of the protection of the so-called ‘real cultural heritage’ (article 9 of the Italian Constitution). The study proceeds by comparing some important sites on the island having similar contextualization, but different strategies for protection: the Archaeological Park of Porto Torres, Su Nuraxi in Barumini, registered since 1997 in the World Heritage List of UNESCO, and the archaeological area of Neapolis (Oristano). From comparisons and analysis carried out in selected areas it was possible to focus attention on some critical aspects of the UNESCO rules and on contradictions between the operational guidelines and the objectives that the organization provides for the protection of property. In the wake of new reforms for the reorganization of the Ministry of Heritage, Culture and Tourism, the critical issues discussed in this paper appear even more evident in Sardinia. The idea of a ‘protection of the exceptional’ appears to reduce the opportunities of intervention, by isolating the evidence from its context and making the action of protection inadequate for the territory and for the same items contained therein

The future (?) of effective protection

This paper aims at a comparative reading of some archaeological remains in the island of Sardinia, starting from a reflection on the UNESCO discipline, which introduces a hierarchy of cultural heritage based on the level of worthiness of protection and provides enhanced protection for the goods that are on its list. The main goal of the study is to investigate in parallel the application of this ‘selective appreciation’ on the actual context of the protection of the so-called ‘real cultural heritage’ (article 9 of the Italian Constitution). The study proceeds by comparing some important sites on the island having similar contextualization, but different strategies for protection: the Archaeological Park of Porto Torres, Su Nuraxi in Barumini, registered since 1997 in the World Heritage List of UNESCO, and the archaeological area of Neapolis (Oristano). From comparisons and analysis carried out in selected areas it was possible to focus attention on some critical aspects of the UNESCO rules and on contradictions between the operational guidelines and the objectives that the organization provides for the protection of property. In the wake of new reforms for the reorganization of the Ministry of Heritage, Culture and Tourism, the critical issues discussed in this paper appear even more evident in Sardinia. The idea of a ‘protection of the exceptional’ appears to reduce the opportunities of intervention, by isolating the evidence from its context and making the action of protection inadequate for the territory and for the same items contained therein

Many-nodes/many-links spinfoam: the homogeneous and isotropic case

I compute the Lorentzian EPRL/FK/KKL spinfoam vertex amplitude for regular graphs, with an arbitrary number of links and nodes, and coherent states peaked on a homogeneous and isotropic geometry. This form of the amplitude can be applied for example to a dipole with an arbitrary number of links or to the 4-simplex given by the compete graph on 5 nodes. All the resulting amplitudes have the same support, independently of the graph used, in the large j (large volume) limit. This implies that they all yield the Friedmann equation: I show this in the presence of the cosmological constant. This result indicates that in the semiclassical limit quantum corrections in spinfoam cosmology do not come from just refining the graph, but rather from relaxing the large j limit.Comment: 8 pages, 4 figure

Compatibility of radial, Lorenz and harmonic gauges

We observe that the radial gauge can be consistently imposed \emph{together} with the Lorenz gauge in Maxwell theory, and with the harmonic traceless gauge in linearized general relativity. This simple observation has relevance for some recent developments in quantum gravity where the radial gauge is implicitly utilized.Comment: 9 pages, minor changes in the bibliograph

Spinfoams in the holomorphic representation

We study a holomorphic representation for spinfoams. The representation is obtained via the Ashtekar-Lewandowski-Marolf-Mour\~ao-Thiemann coherent state transform. We derive the expression of the 4d spinfoam vertex for Euclidean and for Lorentzian gravity in the holomorphic representation. The advantage of this representation rests on the fact that the variables used have a clear interpretation in terms of a classical intrinsic and extrinsic geometry of space. We show how the peakedness on the extrinsic geometry selects a single exponential of the Regge action in the semiclassical large-scale asymptotics of the spinfoam vertex.Comment: 10 pages, 1 figure, published versio

Contraints on Matter from Asymptotic Safety

Recent studies of the ultraviolet behaviour of pure gravity suggest that it admits a non-Gaussian attractive fixed point, and therefore that the theory is asymptotically safe. We consider the effect on this fixed point of massless minimally coupled matter fields. The existence of a UV attractive fixed point puts bounds on the type and number of such fields.Comment: 5 pages, 2 figures, revtex4; introduction expande

Second-order amplitudes in loop quantum gravity

We explore some second-order amplitudes in loop quantum gravity. In particular, we compute some second-order contributions to diagonal components of the graviton propagator in the large distance limit, using the old version of the Barrett-Crane vertex amplitude. We illustrate the geometry associated to these terms. We find some peculiar phenomena in the large distance behavior of these amplitudes, related with the geometry of the generalized triangulations dual to the Feynman graphs of the corresponding group field theory. In particular, we point out a possible further difficulty with the old Barrett-Crane vertex: it appears to lead to flatness instead of Ricci-flatness, at least in some situations. The observation raises the question whether this difficulty remains with the new version of the vertex.Comment: 22 pages, 18 figure

On the Ultraviolet Behaviour of Newton's constant

We clarify a point concerning the ultraviolet behaviour of the Quantum Field Theory of gravity, under the assumption of the existence of an ultraviolet Fixed Point. We explain why Newton's constant should to scale like the inverse of the square of the cutoff, even though it is technically inessential. As a consequence of this behaviour, the existence of an UV Fixed Point would seem to imply that gravity has a built-in UV cutoff when described in Planck units, but not necessarily in other units.Comment: 8 pages; CQG class; minor changes and rearrangement

Numerical indications on the semiclassical limit of the flipped vertex

We introduce a technique for testing the semiclassical limit of a quantum gravity vertex amplitude. The technique is based on the propagation of a semiclassical wave packet. We apply this technique to the newly introduced "flipped" vertex in loop quantum gravity, in order to test the intertwiner dependence of the vertex. Under some drastic simplifications, we find very preliminary, but surprisingly good numerical evidence for the correct classical limit.Comment: 4 pages, 8 figure

Selection of the Cross-Section Design for the LHC Main Dipole

With the aim of selecting the most suitable design for the series production of the LHC main dipoles, several possible configurations were analysed with respect to admissible component tolerances and structural stability, field level, field quality, number and weight of parts. Two alternatives designs, featuring common collars made out of aluminium alloy and austenitic steel, respectively, were finally compared in detail. Although both designs are almost equivalent at nominal conditions, the austenitic steel collar structure turned out to be far less sensitive to components dimensional variations. This paper reports the main results of the above evaluations, which lead to the choice of austenitic steel collars for the LHC main dipoles