Factor models and the credit risk of a loan portfolio

Factor models for portfolio credit risk assume that defaults are independent conditional on a small number of systematic factors. This paper shows that the conditional independence assumption may be violated in one-factor models with constant default thresholds, as conditional defaults become independent only including a set of observable (time-lagged) risk factors. This result is confirmed both when we consider semi-annual default rates and if we focus on small firms. Maximum likelihood estimates for the sensitivity of default rates to systematic risk factors are obtained, showing how they may substantially vary across industry sectors. Finally, individual risk contributions are derived through Monte Carlo simulation.Asset correlation, factor models, loss distribution, portfolio credit risk, risk contributions

Heavy ion fusion reactions far below barrier and their astrophysical implications

openFusion reactions between heavy nuclei have been an hot topic in nuclear physics since the first experiments took place in the 80s: amidst the plethora of subjects involved, the study of low energy collision dynamics is one of the most prolific and interesting fields of study, especially because of its tight connection with stellar thermonuclear processes. In this context, the experimental work presented in this thesis aims to extend the current knowledge about fusion between medium-light nuclei at energies far below the Coulomb barrier, particularly looking for the hindrance phenomenon. The investigation of medium-light systems helps understanding the behaviour of the lighter ones, especially the processes of carbon and oxygen burning in the late stages of star evolution. This thesis work consists of the experimental study of such medium-light systems, involving 12C and heavier nuclei like 24-26Mg and 28Si, more specifically the fusion reaction 12C+26Mg. The measured cross sections are discussed and compared to the predictions of current theoretical models.Fusion reactions between heavy nuclei have been an hot topic in nuclear physics since the first experiments took place in the 80s: amidst the plethora of subjects involved, the study of low energy collision dynamics is one of the most prolific and interesting fields of study, especially because of its tight connection with stellar thermonuclear processes. In this context, the experimental work presented in this thesis aims to extend the current knowledge about fusion between medium-light nuclei at energies far below the Coulomb barrier, particularly looking for the hindrance phenomenon. The investigation of medium-light systems helps understanding the behaviour of the lighter ones, especially the processes of carbon and oxygen burning in the late stages of star evolution. This thesis work consists of the experimental study of such medium-light systems, involving 12C and heavier nuclei like 24-26Mg and 28Si, more specifically the fusion reaction 12C+26Mg. The measured cross sections are discussed and compared to the predictions of current theoretical models

Virtual Archaeology and museums, an italian perspective

[EN] The growing number of virtual museums and applications today available arises many questions concerning the problems connected to their fruition and maintenance. This paper aims at setting up an analysis of the topic, through the steps of three VM projects carried on by the Virtual Heritage Lab (2008, 2010, 2012 (in progress)). Such case studies are taken into account on the basis of three topics: technical maintenance, reliability and semantic density. The analysis aims also at contributing the debate on the future development of VMs and on the management of the relationships between reliability and wide dissemination.[ES] El creciente número de museos y aplicaciones virtuales disponibles en la actualidad plantea diversas problemáticas en cuanto a uso y mantenimiento se refiere. El presente proyecto intenta establecer un análisis del problema a través del estudio de tres proyectos de musealización virtual realizados por el Virtual Heritage Lab en el Istituto per le Tecnologie Applicate ai Beni Culturali del CNR (proyectos realizados en los años 2008, 2009 y 2012(en fase de realización). Tales proyectos se realizan en base a tres aspectos: el mantenimiento, la fiabilidad en la gestión de los datos y la densidad semántica. El estudio aporta una contribución al debate sobre el desarrollo de futuros museos virtuales y las posibles formas de abordar la compleja relación entre el rigor científico y la divulgación.Palombini, A.; Pescarin, S. (2011). Virtual Archaeology and museums, an italian perspective. Virtual Archaeology Review. 2(4):151-154. https://doi.org/10.4995/var.2011.4575OJS15115424FORTE M. and AA.VV., 2008, "La Villa di Livia, un percorso di ricerca di archeologia virtuale", L'Erma di Bretschneider, Roma.MUELLER P, ZENG G, WONKA P AND VAN GOOL L, 2007, Image-based Procedural Modeling of Facades, ACM Transactions on Graphics, volume 26, number 3, article number 85. pages 1-9. Proceedings of SIGGRAPH 2007.PESCARIN S., PIETRONI E., FERDANI D., in press, "A procedural approach to the modeling of urban historical contexts" in Francisco Contreras & Fco. Javier Melero (Eds) Fusion of Cultures Proceedings of the 38th Conference on Computer Applications and Quantitative Methods in Archaeology Granada, Spain, April 2010

Pierre Schaeffers typo-morphology of sonic objects.

SIGLEAvailable from British Library Document Supply Centre- DSC:D174501 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Competitività orizzontale e verticale nel ciclismo professionistico: alcune riflessioni sul circuito pro tour

1. La recente evoluzione delle forme organizzative del ciclismo professionistico - 2. Il Pro Tour: aspetti organizzativi, strategie ed obiettivi della lega chiusa - 3. Competitività verticale e orizzontale all’interno del Pro Tour: alcune evidenze - ConclusioniCompetitività verticale e orizzontale, pro tour, economia del ciclismo

Downconverting Module Architectures for High Performance Multipixel Cameras

Multipixel cameras represent an emerging topology for arrays receivers, improving speed and accuracy of both security scanning systems and radioastronomical sky surveys by means of a matrix of phased elements. Difficulties in the generation and proper distribution to each pixel of the local oscillator signal still limit their use to frequency ranges below a few GHz or at least seriously affect the complexity of the implementable cameras. This work presents a full comparison between two possible system architectures, alternatively based on LO frequency multiplication or subharmonic mixing strategies, aiming to overcome the aforesaid limitations: design and performance of two compact test vehicles in MMIC technology, both operating in the Q-band frequency range with ultrabroadband IF section, are reported

Electromagnetic Precursors in Complex Layered Media

The dynamical evolution of an ultrawideband electromagnetic pulse as it propagates through a temporally dispersive and attenuative medium is a classical problem in electromagnetic wave theory with considerable practical importance dating back to seminal works conducted in 1914. With the use of modern asymptotic theory and numerical techniques, propagation of canonical pulses into complex (attenuative and dispersive) media have been analyzed and recently extended to nonlinear materials. The materials of interest for this research are modeled after realistic biological tissues. The mathematically rigorous and more accurate physical model of electromagnetic energy transfer into the biological materials modeled will be used as input to the FitzHugh-Nagumo circuit equivalent model for an excitable neuron. This detailed analysis will provide a new point of view to working groups and standardization committees in the eld of non-ionizing radiation safety that is based on so-called athermal effects

Riproducibilità a vario titolo del patrimonio: situazione e prospettive

The paper approaches the rights of reproducing Cultural Heritage items, in every possible aspects and for both commercial and non-commercial purposes. The legal situation is currently vague and not defined, as it is in other parts of Europe and the world. Two valid arguments are confronting each other: on the one hand, the public demand for data openness, on the other, the public institutions’ desire to earn money, at least enough to justify conservation expenses. After a discussion on the current situation, where digital revolution and 3D technology changed even the common understanding of ‘reproduction’ processes, a possible solution is presented, in order to satisfy both needs

Il Festival delle Ciaramelle di Amatrice

A note from the Festival Director. Il Festival delle Ciaramelle, Amatrice (RI) 5-7 August 2016, Perugia 12 November 2016.Una nota del Direttore del Festival. Il Festival delle Ciaramelle, Amatrice (RI) 5-7 Agosto 2016, Perugia 12 Novembre2016.