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

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

Teflon Injection into the Trachea Causes Predictable Fibroblastic Response and Collagen Deposition: A Pilot Study.

BackgroundExpiratory central airway collapse is an increasingly recognized abnormality of the central airways and may be present in as many as 22% of patients evaluated for chronic obstructive pulmonary disease and/or asthma. Many current treatment options require invasive procedures that have been shown to cause significant morbidity and mortality. To test the hypothesis that Teflon injection will induce sufficient fibroblast proliferation and collagen deposition, we evaluated the time course on the effect of Teflon injection in the posterior membranous trachea on the histopathology of the tracheobronchial tree.MethodsSix Yucatan Pigs were assigned to undergo general anesthesia and injection of 0.3 to 0.5 mL of sterile Teflon paste in 50% glycerin into the posterior membranous tracheal wall. A control pig received an equivalent volume of glycerin. Animals were euthanized in predefined intervals and tracheas were excised and examined under light microscopy for identifying fibroblast proliferation and collagen deposition.ResultsCompared with the control pig, the Teflon injection site showed tissue reaction of fibrohistiocytic proliferation and subsequent collagen deposition in all animals. Furthermore, the increased fibroblast proliferation and collagen deposition were time dependent (P<0.01).ConclusionThis pilot study demonstrates histopathologic changes in the trachea after Teflon injection, comprised of increased fibroblast activity and collagen deposition that could be of potential use in creating greater airway rigidity in patients with sever diffuse excessive dynamic airway collapse

Distributed Amplifiers in MMIC Technology based on Composite Right/Left-Handed Transmision Lines

Abstract – Three MMIC distributed amplifiers based on Composite Right/Left-Handed Transmission Lines are presented in order to illustrate the actual performance of these devices, and the features that can be obtained with this distributed amplifier topology. Measurement results and/or qualified simulations have been included for two amplifiers with dual-band performance and for a high-power one. Also different frequency bands are illustrated, with examples at X-, C- and S-band operation.Universidad de Málaga.Campus de Excelencia Internacional Andalucía Tech. Ministerio de Ciencia e Innovación (Programa Consolider-Ingenio 2010) under Grant CSD2008-00066 (‘EMET’), and Junta de Andalucía (Spain) under Grant P10-TIC-6883

Electron reconstruction performance and sensitivity determination of the h → ZZ∗ → 4e cross-section at sqrt(s) = 10 TeV Muon Collider

openThe discovery of the Higgs boson at LHC completed the picture of the Standard Model. However, observations like dark matter and neutrino masses suggest that SM might be incomplete. Also, the Higgs boson and its interactions are yet to be fully characterized. A Future Collider is sought to tackle those challenges. At the highest energies, the goal of such a scientific program will be to directly test Beyond SM hypotheses. At the electroweak energy scale, the main goal will be the characterization of the Higgs boson: the measurement of its self-coupling would lead to the determination of the Higgs potential, while the precise measurement of its coupling with fermions and gauge bosons could hint to new physics in the highest-order corrections, in case a deviation was found. The Muon Collider is a novel machine that could allow both high energy and high precision measurements in a single facility. At sqrt(s)=10 TeV, a Muon Collider overqualifies as a Higgs factory, with high enough single and double Higgs production rates to meet the required accuracies in the Higgs sector’s measurements. However, the huge background expected from the decay of colliding muons could hinder the physics performance of a muon collider experiment, if not mitigated: one of the possibilities to reduce its effect is to exploit the different position, time and energy properties with respect to particles from the hard scattering. In this context, the present thesis aims at characterizing the CRILIN electromagnetic calorimeter, a novel detector technology able to deliver the space, time and energy resolutions required for the Muon Collider’s environment. The work consists in the evaluation of the simulated reconstruction performance of single electrons with the CRILIN calorimeter in presence of the beam-induced background, followed by the optimization of the mitigation strategies. The resulting performance is then exploited in a parametric analysis of the sensitivity to the single SM Higgs decay to two Z0, each decaying to an electron-positron pair.The discovery of the Higgs boson at LHC completed the picture of the Standard Model. However, observations like dark matter and neutrino masses suggest that SM might be incomplete. Also, the Higgs boson and its interactions are yet to be fully characterized. A Future Collider is sought to tackle those challenges. At the highest energies, the goal of such a scientific program will be to directly test Beyond SM hypotheses. At the electroweak energy scale, the main goal will be the characterization of the Higgs boson: the measurement of its self-coupling would lead to the determination of the Higgs potential, while the precise measurement of its coupling with fermions and gauge bosons could hint to new physics in the highest-order corrections, in case a deviation was found. The Muon Collider is a novel machine that could allow both high energy and high precision measurements in a single facility. At sqrt(s)=10 TeV, a Muon Collider overqualifies as a Higgs factory, with high enough single and double Higgs production rates to meet the required accuracies in the Higgs sector’s measurements. However, the huge background expected from the decay of colliding muons could hinder the physics performance of a muon collider experiment, if not mitigated: one of the possibilities to reduce its effect is to exploit the different position, time and energy properties with respect to particles from the hard scattering. In this context, the present thesis aims at characterizing the CRILIN electromagnetic calorimeter, a novel detector technology able to deliver the space, time and energy resolutions required for the Muon Collider’s environment. The work consists in the evaluation of the simulated reconstruction performance of single electrons with the CRILIN calorimeter in presence of the beam-induced background, followed by the optimization of the mitigation strategies. The resulting performance is then exploited in a parametric analysis of the sensitivity to the single SM Higgs decay to two Z0, each decaying to an electron-positron pair

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

Exploring the effect of different hints on flow state in virtual reality

LAUREA MAGISTRALEIl flow è uno stato di intensa concentrazione e coinvolgimento, che è appagante per le persone che lo sperimentano e quindi generalmente ricercato dai creatori di giochi ed esperienze virtuali. La realtà virtuale (VR) è nota per essere una delle tecnologie più immersive disponibili oggi. Come tale, ha un grande potenziale per favorire lo stato di flow nei suoi utenti. Questo lavoro cerca di determinare quali caratteristiche di design favoriscano maggiormente il flow, per quanto riguarda il guidare l’utente. In particolare, questa ricerca esamina se in una VR escape room, i suggerimenti di testo o gli spunti luminosi siano più efficaci per favorire i sentimenti di flusso. Il processo di ricerca ha incluso la progettazione e l’implementazione di una VR escape room da zero, per creare l’ambiente perfetto per gli esperimenti, un’esperienza VR in cui l’obiettivo finale e i passi intermedi sono definiti con precisione. Questo permette di dare suggerimenti rilevanti ad ogni fase dell’esperienza, e di esaminare gli effetti del design dei suggerimenti sul flow. L’intensità dello stato di flow risultante è stata valutata attraverso la Activity Flow State Scale (AFSS) progettata da Payne et al. e sono stati raccolti anche dati qualitativi, dall’osservazione diretta e dai commenti degli utenti. Il punteggio AFSS, la durata dell’esperienza VR, e la durata stimata dagli utenti, sono stati confrontati tra la versione della VR escape room che presenta i suggerimenti tramite testo e quella in cui gli oggetti rilevanti brillano. Questi dati sono stati poi collegati ai risultati derivanti dall’analisi tematica dell’osservazione diretta e dei commenti degli utenti. Infine, sono state estratte intuizioni e linee guida generali per creare esperienze VR orientate al flow.Flow state is a state of intense focus and engagement, which is fulfilling for people experiencing it and therefore generally sought-after by creators of virtual games and experiences. Virtual Reality (VR) is known to be one of the most immersive technologies available today. As such, it has great potential to foster flow state in its users. This work tries to determine which design characteristics favor flow the most, with regard to providing guidance to the user. In particular, this research examines whether in a VR escape room, text hints or glowing cues are more effective to foster feelings of flow. The research process included design and implementation of the VR escape room from the ground up, to create the perfect setting for the experiments, a VR experience in which ultimate goal and intermediate steps are precisely defined. This allows to give relevant hints every step of the experience, and to examine the effects of hints design on flow. The intensity of the resulting flow state has been evaluated through the Activity Flow State Scale (AFSS) designed by Payne et al., and qualitative data has also been gathered, from direct observation and user comments. AFSS score, duration of the VR experience, and duration estimated by the users, have been compared between the version of the VR escape room which presents hints as text prompts and the one in which relevant objects glow. This data has then been connected to findings resulting from the thematic analysis of direct observation and user comments. Lastly, general insights and guidelines have been extracted, to inform designers and game developers willing to create flow-oriented VR experiences

Comparison Of Three Fluoride Dentifrice Products In The Prevention Of White Spot Lesions In Orthodontic Treatment

Introduction:. During the course of orthodontic treatment, enamel decalcification is a common problem. Demineralized enamel, the precursor to caries formation, can be attributed to fixed orthodontic appliances and prolonged exposure to bacterial plaque. Progression to clinically detectable white spot lesions may occur as early as one month following the placement of orthodontic appliances. Such problems have influenced clinicians to search for a solution. Because fluoride treatment immediately upon debonding is not advocated, clinicians have proposed fluoride treatment and fluoride-releasing materials at the commencement of the therapy. The two new anti-cavity toothpastes, ClinproTM 5000 with 1.1% Sodium Fluoride and ClinproTM Tooth Crème with 0.21% Sodium Fluoride have been shown to be useful in reduction of white spot lesions. Both the Clinpro TM products (3M ESPE) contain fluoride as well as tri-calcium phosphate, which are components naturally found in saliva. The aim of this study is to determine if ClinproTM 5000, ClinproTM Tooth Crème, or MI-Paste Plus has an effect on the formation and resolution of white spot lesions for patients undergoing orthodontic treatment. Methods: Three prospective groups of 40 patients undertaking routine orthodontic treatment were evaluated (total recruitment of 120 subjects). Patients must have their permanent dentition, be 12 years or older, and have not used extensive fluoride regimes before. Patients were chosen if they appear that they would be compliant as judged by the investigator. The selected product was brushed on the teeth by the patient for two minutes, twice daily for a total of 4 months. After brushing, the patients were instructed to expectorate only, not rinse t, t eat or drink anything for at least 30 minutes. The subjects were observed every 4 weeks. At each visit, 3 intraoral photos were taken (frontal and buccal views) and measurements based on the Enamel Decalcification Index (EDI) will be recorded. The Enamel Decalcification Index was used to determine the number of white spot lesions and caries risk detected in these photographic records. Also, a brushing diary was reviewed. A trained member of the 3M ESPE Clinical Research group did monitor the study by means of visits to the clinic to evaluate patient charts, study data, and study photographs. Results: Altogether, the results provided strong support with regard for ClinproTM 5000 providing superior enamel protection against decalcification when compared to ClinproTM Crème, and MI Paste. Conclusions: The use of ClinproTM 5000, ClinproTM Crème, and MI paste demonstrated less formation of white spot lesions when compared to data in the literature. ClinproTM 5000 had a marginally better affect compared to the other two products

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