The cost of firms' debt financing

We provide an assessment of the determinants of the risk remia paid by non-financial corporations on long-term bonds. By looking at 5,500 issues over the period 2005-2012, we find that in recent years the sovereign debt market turbulence has been a major driver of corporate risk. Compared with the three-year period 2005-07 before the global financial crisis, in the years 2010-12 Italian, Spanish and Portuguese firms paid on average between 70 and 120 basis points of additional premium due to the negative spillovers from the sovereign debt crisis, while German firms got a discount of 40 basis points

Zen

The ZEN (North Area Expansion) district, today renamed San Filippo Neri district, is located in the middle of the northernmost part of Piana dei Colli, surrounded by Mount Pellegrino, Mount Gallo, and Mount Billiemi, as a supposed prolongation of via della Libertà and near the Gulf of Mondello. The Piana dei Colli is dotted by the eighteenth-nineteenth century vil- las and the Pallavicino, Cardillo, Tommaso Natale, and Partanna Mondello villages. Together with these settlements there are smaller aggregations of houses developing along some historical routes. In the second half of XX century ZEN, villages, and historic villas became in different ways the “pre-existences” of the north side of Piana dei Colli, privileged witnesses of the double growth coming from south and north: from the compact city and from Mondello and Sferracavallo. This process produced around ZEN a juxtaposition of different ways of inhabiting, many of which are the opposite of the council-house building, as the large number of detached houses spread all around the district. A further critical condition caused by the layout of the road network is added to this complex situation. The highway, the beltway, the provincial road, via Lanza di Scalea— which is completed with the ring road built around ZEN at the end of the XX century—made the connections from and to Punta Raisi airport more flowing and turned properties which not long ago were in- accessible and of modest land value into desirable and expensive buildable lands. However, at the same time, these infrastructures have affected the agricultural structure and have cut the natural links connecting the villages among them and with the fields. The infra- structures, together with the enclosures produced by the sprawl, have shattered the area in a sequence of hermetic rectangles spread homogeneously in a north-south direction. The most evident fracture is around ZEN, because the ring road builds a sort of medieval wall all around the district, making it victim of an a priori isolation. These preliminary remarks point out that the relations between road-area and road-building are fundamental to study the district and to understand an area divided in- to watertight compartments. Therefore the planning will be focused on the edges and some of the unresolved areas inside the district itself

From Relational Data to Graphs: Inferring Significant Links using Generalized Hypergeometric Ensembles

The inference of network topologies from relational data is an important problem in data analysis. Exemplary applications include the reconstruction of social ties from data on human interactions, the inference of gene co-expression networks from DNA microarray data, or the learning of semantic relationships based on co-occurrences of words in documents. Solving these problems requires techniques to infer significant links in noisy relational data. In this short paper, we propose a new statistical modeling framework to address this challenge. It builds on generalized hypergeometric ensembles, a class of generative stochastic models that give rise to analytically tractable probability spaces of directed, multi-edge graphs. We show how this framework can be used to assess the significance of links in noisy relational data. We illustrate our method in two data sets capturing spatio-temporal proximity relations between actors in a social system. The results show that our analytical framework provides a new approach to infer significant links from relational data, with interesting perspectives for the mining of data on social systems.Comment: 10 pages, 8 figures, accepted at SocInfo201

The LHAASO PeVatron bright sky: what we learned

The recent detection of 12 gamma-ray Galactic sources well above E > 100 TeV by the LHAASO observatory has been a breakthrough in the context of Cosmic Ray (CR) origin search. Although most of these sources are unidentified, they are often spatially correlated with leptonic accelerators, like pulsar and pulsar wind nebulae (PWNe). This dramatically affects the paradigm for which a gamma-ray detection at E > 100 TeV implies the presence of a hadronic accelerator of PeV particles (PeVatron). Moreover, the LHAASO results support the idea that sources other than the standard candidates, Supernova Remnants, can accelerate Galactic CRs. In this context, the good angular resolution of future Cherenkov telescopes, such as the ASTRI Mini-Array and CTA, and the higher sensitivity of future neutrino detectors, such as KM3NeT and IceCube-Gen2, will be of crucial importance. In this brief review, we want to summarize the efforts done up to now, from both theoretical and experimental points of view, to fully understand the LHAASO results in the context of the CR acceleration issue.Comment: Accepted for the special Issue "High Energy Multi-Messenger Astrophysics: Latest Research and Reviews" of the journal "Applied Science

The Cowl - v.63 - n.13 - Feb 5, 1998

The Cowl - student newspaper of Providence College. Vol 63 - No.13 - Feb 5, 1998. 24 pages

Characterisation of spatial network-like patterns from junctions' geometry

We propose a new method for quantitative characterization of spatial network-like patterns with loops, such as surface fracture patterns, leaf vein networks and patterns of urban streets. Such patterns are not well characterized by purely topological estimators: also patterns that both look different and result from different morphogenetic processes can have similar topology. A local geometric cue -the angles formed by the different branches at junctions- can complement topological information and allow to quantify the large scale spatial coherence of the pattern. For patterns that grow over time, such as fracture lines on the surface of ceramics, the rank assigned by our method to each individual segment of the pattern approximates the order of appearance of that segment. We apply the method to various network-like patterns and we find a continuous but sharp dichotomy between two classes of spatial networks: hierarchical and homogeneous. The first class results from a sequential growth process and presents large scale organization, the latter presents local, but not global organization.Comment: version 2, 14 page