The scientific instruments in the museum of the Politecnico di Torino

The paper wants to illustrate scientific instruments in the collections of the Museum of Politecnico di Torino, distributed in various departments in respect of both historical consistency and didactic use.In particular the attention is focused on scientific instruments for electric and electrotechnical measurements

Natural clustering: the modularity approach

We show that modularity, a quantity introduced in the study of networked systems, can be generalized and used in the clustering problem as an indicator for the quality of the solution. The introduction of this measure arises very naturally in the case of clustering algorithms that are rooted in Statistical Mechanics and use the analogy with a physical system.Comment: 11 pages, 5 figure enlarged versio

Occurrence of the Redglobe strain of Grapevine leafroll-associated virus 2 in table and wine grape varieties in Italy

Research NoteThe Redglobe strain of Grapevine leafrollassociated virus 2 (GLRaV-2-RG) is a recently discovered closterovirus so far reported to infect solely cv. Redglobe. A survey for this virus 2 in about 380 accessions of table and wine grape varieties conducted during 2001-2003 proved that GLRaV-2-RG was present also in other table grape varieties, though to a smaller extent, while it was never detected in wine varieties.

Hierarchical Partial Planarity

In this paper we consider graphs whose edges are associated with a degree of {\em importance}, which may depend on the type of connections they represent or on how recently they appeared in the scene, in a streaming setting. The goal is to construct layouts of these graphs in which the readability of an edge is proportional to its importance, that is, more important edges have fewer crossings. We formalize this problem and study the case in which there exist three different degrees of importance. We give a polynomial-time testing algorithm when the graph induced by the two most important sets of edges is biconnected. We also discuss interesting relationships with other constrained-planarity problems.Comment: Conference version appeared in WG201

Preliminary results on population dynamics and host plants of

This work dealt with Hyalesthes obsoletus, which is the only known vector of Bois noir disease in grapevine. Investigation centered on its flight activity and occurrence on bindweed and stinging nettle and, to a lesser extent, hedge bindweed and dead-nettle in North-Eastern Italy. The survey underlined the importance of bindweed in the insect lifecycle in Northern Italy, where only data from stinging nettle had previously been recorded. H. obsoletus nymphs were found for the first time on the roots of dead-nettle, which proved to be a new host plant. The first observation in Italy of nymphs on hedge bindweed roots was also recorded

Competing interactions in arrested states of colloidal clays

Using experiments, theory and simulations, we show that the arrested state observed in a colloidal clay at intermediate concentrations is stabilized by the screened Coulomb repulsion (Wigner glass). Dilution experiments allow us to distinguish this high-concentration disconnected state, which melts upon addition of water, from a low-concentration gel state, which does not melt. Theoretical modelling and simulations reproduce the measured Small Angle X-Ray Scattering static structure factors and confirm the long-range electrostatic nature of the arrested structure. These findings are attributed to the different timescales controlling the competing attractive and repulsive interactions.Comment: Accepted for publication in Physical Review Letter

Redundant variables and Granger causality

We discuss the use of multivariate Granger causality in presence of redundant variables: the application of the standard analysis, in this case, leads to under-estimation of causalities. Using the un-normalized version of the causality index, we quantitatively develop the notions of redundancy and synergy in the frame of causality and propose two approaches to group redundant variables: (i) for a given target, the remaining variables are grouped so as to maximize the total causality and (ii) the whole set of variables is partitioned to maximize the sum of the causalities between subsets. We show the application to a real neurological experiment, aiming to a deeper understanding of the physiological basis of abnormal neuronal oscillations in the migraine brain. The outcome by our approach reveals the change in the informational pattern due to repetitive transcranial magnetic stimulations.Comment: 4 pages, 5 figures. Accepted for publication in Physical Review

Probing the Low Mass X-ray Binaries/Globular Cluster connection in NGC1399

We present a wide field study of the Globular Clusters/Low Mass X-ray Binaries connection in the cD elliptical NGC1399, combining HST/ACS and Chandra high resolution data. We find evidence that LMXB formation likelihood is influenced by GCs structural parameters, in addition to the well known effects of mass and metallicity, independently from galactocentric distance.Comment: in press in the Proceedings of the X-ray 2009 Conference, 7-11 September 2009, Bologna, Ital

Environmental monitoring solution for cultural heritage

Environmental monitoring is crucial factor in the safeguard and conservation of the cultural heritage. Unsuitable environmental conditions can easily accelerate the degradation of several materials and, as consequence, damage the stored artifacts. Moreover, environmental conditions can easily change in an unpredictable way and, therefore, the employment of an environmental monitoring system is mandatory in almost all locations, including museums, storage rooms and outdoor exhibitions. This paper tries to explain the main constraints required for environmental monitoring in the cultural heritage field. Moreover, a novel distributed monitoring system, developed at Politecnico di Torino, is described and compared to several solutions that are commercially available. The proposed solution demonstrated excellent characteristics which satisfy the requirements of environmental monitoring in the cultural heritage at a very competitive cost