A Model of Market Power in Customer Markets

We develop a model for studying dynamic competition in environments with frictions that lead to partial lock-in of customers to products. The dynamic aspects associated with customer retention and acquisition introduce pricing incentives that do not exist in more traditional, static product markets. The proposed model, while highly stylized, maintains certain symmetry properties that allow us to obtain equilibrium existence and uniqueness. We then study the comparative statics of the model and derive a closed-form relationship between average equilibrium markups and the Herfindahl index. We illustrate how the model can be used by analyzing mergers in such a dynamic environment.Martin Lee Johnson Graduate Fellowshi

"Getting Switzerland to move”: E valuation of a new "Sport for All” programme

Summary: Objectives: Even though sports participation in Switzerland appears to be quite elevated, recent research suggests that only about a third of the population are doing enough sports from a health perspective. Methods: Against this background several Swiss health insurance companies together with the Swiss Olympic Association have recently developed a novel approach to get people to start physical exercise: Under the label of > sport clubs offer training and information courses aimed at motivating and helping previously inactive people to take on regular exercise. Results: The paper presents results from an interdisciplinary evaluation of the first three years of the > campaign. Starting from an overview of the basic idea and features of the campaign it asks whether > has reached its self-declared goal of "getting Switzerland moving”. Available evidence on the social background of participants and their further activities shows that by systematically avoiding any reference to conventional notions of sport and by stressing the health and fun aspect instead, > has indeed managed to mobilise an important group with underaverage levels of activity (particularly middle-aged women). In addition, on average the level of physical exercise of participants appears to have increased. Yet, the number of participants is below the original target values and, contrary to the campaign's initial goal, participants are reluctant to leave the programme after one course to take up an independent activity or to join a club. Conclusions: The paper explores the achievements and problems of the campaign so far and offers an explanation of recent problems which can also serve as a basis for the implementation of similar programmes in other countrie

Eine Qualitätskultur für die Gesundheitsförderung!

Zusammenfassung: Qualität und Qualitätsmanagement sind im Projektalltag der Gesundheitsförderung als Begriffe präsent, aber es gibt weder eine klare Begrifflichkeit noch ein homogenes Qualitätsverständnis. Dies ist Ausdruck dafür, dass eine kritische und selbstreflexive Projektkultur zu wenig verankert ist. Ein gutes Projekt- und Qualitätsmanagement ist notwendig, um die Zielerreichung zu optimieren. Es fehlt bislang aber noch an konkreten Umsetzungen, was Qualitätsförderung im Projektalltag bedeutet. Der Artikel zeigt die Notwendigkeit auf, warum sich die Gesundheitsförderung mit Qualität auseinandersetzen muss und was sie gewinnen kann. Er präsentiert ein Projekt des Instituts für Sozial- und Präventivmedizin Zürich, das Qualitätsförderung konkret umsetzt. Gemeinsam mit Projektleitungen werden Instrumente für ein Qualitätsmanagement entwickelt und erprobt, die den kontinuierlichen Prozess der Qualitätsförderung steuern und unterstütze

Stages of change for perceived stress in a Swiss population sample: An explorative study

Summary: Objectives: Data from a cross-sectional survey of the Swiss general population were used in an explorative attempt to apply the transtheoretical model of behavioural change to perceived stress. Methods: The sample comprised 575 respondents who reported having experienced stressful situations in the previous month. Other variables assessed included gender, age, education, reported symptoms, and three constructs representing stages and processes of change as well as self-efficacy. Results: Findings indicated that (1) about one third of respondents appeared to cope successfully with the stressful situations they experienced, one third intended to do so, while one quarter appeared to have no intention of managing their stress more effectively. (2) There was no difference in stage of change distribution by gender or age, while those with higher education were more frequently represented in the latter stages than those with lower education. (3) Those in the maintenance stage reported significantly less symptoms than others. Conclusions: We conclude that the assessment of readiness to change could be of valuable support in designing stage-specific interventions in the area of stress managemen

Material differentiation in forensic radiology with single-source dual-energy computed tomography

The goal of this study was to investigate the use of dual-energy computed tomography (CT) in differentiating frequently encountered foreign material on CT images using a standard single-source CT scanner. We scanned 20 different, forensically relevant materials at two X-Ray energy levels (80 and 130kVp) on CT. CT values were measured in each object at both energy levels. Intraclass correlation coefficient (ICC) was used to determine intra-reader reliability. Analysis of variance (ANOVA) was performed to assess significance levels between X-Ray attenuation at 80 and 130kVp. T test was used to investigate significance levels between mean HU values of individual object pairings at single energy levels of 80 and 130kVp, respectively. ANOVA revealed that the difference in attenuation between beam energies of 80kVp compared to 130kVp was statistically significant (p<0.005) for all materials except brass and lead. ICC was excellent at 80kVp (0.999, p<0.001) and at 130kVp (0.998, p<0.001). T test showed that using single energy levels of 80 and 130kVp respectively 181/190 objects pairs could be differentiated from one another based on HU measurements. Using the combined information from both energy levels, 189/190 object pairs could be differentiated. Scanning with different energy levels is a simple way to apply dual-energy technique on a regular single-energy CT and improves the ability to differentiate foreign bodies with CT, based on their attenuation value

Neutron transport in stochastic geometries. Benchmark calculations and study of a melted reactor core

LAUREA MAGISTRALENegli ultimi anni è andato crescendo l'interesse nella risoluzione dell'equazione del trasporto in mezzi stocastici. In particolare, vengono studiate le miscele binarie stocastiche, utilizzabili in molti campi (diffusione dei contaminanti radioattivi in mezzi geologici, trasporto in mezzi turbolenti per il confinamento della fusione inerziale, attraversamento di schermi di cemento da parte di neutroni e di raggi gamma,..). Le geometrie che trattiamo in questo lavoro sono supposte essere markoviane, cosa che non rispecchia la realtà della maggior parte dei casi che queste geometrie cercano di simulare, ma risulta essere un'approssimazione necessaria. Abbiamo preso in considerazione un problema di trasporto per cui si avevano già dei risultati di riferimento (ottenuti da una geometria planare composta da strati alternati di due materiali). La nostra geometria è invece composta da poligoni creati in modo casuale su un piano ed è markoviana in due dimensioni, cosa che la rende più affine e rappresentativa delle reali geometrie stocastiche. Lo scopo dei nostri calcoli di riferimento è quello di confrontare e analizzare i risultati precedentemente ottenuti e di testare la validità dei modelli del problema che sono stati elaborati. La realizzazione della geometria markoviana è basata sul processo descritto da Switzer nel 1964 che permette di creare una geometria planare con proprietà markoviane. Per ognuna delle molte realizzazioni geometriche effettuate, abbiamo risolto il problema di trasporto neutronico con il codice Monte Carlo creato al CEA, TRIPOLI-4. Abbiamo poi mediato i risultati e costruito gli istogrammi per avere informazioni anche sulle distribuzioni delle quantità cercate.Nella seconda parte della tesi, abbiamo utilizzato la stessa procedura di realizzazione di geometrie markoviane e di risoluzione dell'equazione del trasporto per simulare un nocciolo fuso di un PWR. Anche in questo caso, non conosciamo le distribuzioni dei materiali che compongono il core, ma solo le loro proprietà. Abbiamo analizzato tre diversi casi, ognuno caratterizzato da un certo livello di mescolanza degli elementi del nocciolo e abbiamo cercato il valore del k_eff, per vedere come varia e come si distribuisce quando i materiali si mescolano in modo casuale gli uni con gli altri.The interest in resolving the equation of transport in stochastic media has continued to increase these last years. Binary stochastic mixtures are particularly studied because of their several applications (diffusion of radioactive contaminants in geological media, transport in turbolent media for the inertial confinement fusion, crossing of neutrons or gamma rays throughout concrete shields, ...). The geometries we deal with in this present thesis are assumed to be Markovian, which is never the case in usual environments, but which is a necessary approximation. We consider a two-suite neutron transport problem for which other benchmark results (based on a stochastic geometry composed by a labeled plane filled with two alternating materials) were already performed. The geometry we use is composed by random polygons built in a plane and it is Markovian in two dimensions, thus it better represents a real stochastic geometry. The goal of our benchmark calculations is to compare and analyze the previous obtained results and to test the validity of different elaborated models of the problem. The creation of the Markovian planar geometry is done in accordance with the process described by Switzer in 1964, which allows to construct a two-dimensional geometry with Markovian properties. For each one of the several geometry realizations, we solve the neutron transport problem with the Monte Carlo code TRIPOLI-4, developed at CEA. Then, we average the results and we build histograms to see also the distributions. In the second part of the thesis, we use the same procedure of Markovian geometry creation and stochastic resolution of transport equation to simulate a melted core of a PWR reactor. In this case, we do not know the distributions of the materials composing the core and we study three cases, each one characterized by a different material mixing level. We obtain and analyze the value of k_eff, to see how it varies and distributes depending on the way the materials actually mix after the fusion of the core

BIM interoperability in the structural engineer workflow : state-of-the-art from a literature review

LAUREA MAGISTRALEIl metodo del Building Information Modeling si è affermato come approccio principale nel processo di digitalizzazione nell’industria dell’architettura, dell’ingegneria, e delle costruzioni. Nel corso degli ultimi cinque/sei anni, l’introduzione di nuovi standard ha reso obbligatorio in un numero crescente di progetti l’uso del BIM richiedendo grandi sforzi in termini di formazione di professionisti, certificazione, etc. L’ingegnere strutturale non è escluso dal gruppo dei professionisti che ha dovuto cambiare il proprio flusso di lavoro, spostandosi dall’uso del CAD all’ambiente BIM. Le possibilità offerte da questa metodologia hanno permesso di ottimizzare i processi, ridurre i tempi, i costi e gli errori. Un ruolo importante in questo processo è giocato dallo scambio dei modelli tra gli ambienti BIM e FEM. Infatti, un ingegnere dovrebbe essere in grado di scambiare questi modelli senza perdere informazioni, in modo da avere una base affidabile su cui lavorare. L’obbiettivo di questa tesi è quello di investigare le metodologie e i risultati legati a questo tema presenti nella letteratura, considerando gli scambi BIM-to-BIM, BIM-to-FEM e FEM-to-FEM. Partendo da un corposo campione della letteratura è stato possibile analizzare l’interoperabilità sotto il punto di vista degli approcci, della struttura e dei risultati. Da questi studi è stato inoltre possibile concludere che diversi problemi possono emergere durante lo scambio di dati tra diversi software. È inoltre emerso che questi problemi sono attribuibili sia a una non eccellente implementazione nei software, sia ad una mancanza di conoscenza degli strumenti di import/export da parte degli autoriBuilding Information Modeling method has become established as the leading process in the complete digitalization of the modern architecture, engineering, and construction industry. Through the last five/six years, the introduction of new standards mandates the use of BIM methodology in an increasing number of projects requiring a huge effort in terms of training of professionals, certification, etc. The structural engineer is not excluded from the group of professionals that have to change their design workflow, shifting from the use of CAD systems to the BIM environment. Many new possibilities are now given to optimize the processes, experiencing reduction of time, costs, and errors. The necessity of exchanging models into, and between, BIM and FEM environments plays a crucial role. Indeed, an engineer should be able to trade models without information loss in order to always have a reliable basis to work with. The Aim of this MSc thesis is to investigate the methodologies and the results found in the literature regarding the theme of the BIM workflow for the structural engineer, considering the BIM-to-BIM, BIM-to-FEM, and FEM-to-FEM model exchanges. From a hefty sample of papers and thesis present in the literature it was possible to analyze the subject interoperability from the point of view of the procedures, structure, and results. From these studies it was possible to state that many drawbacks arise during the exchange of data between different software. It emerged that these problems are ascribable both to a not proper implementation in the software and to a lack of knowledge from the authors of the import/export tools

Il progetto “statuale” di Giovanni Antonio Orsini del Balzo.

Partendo dalla categoria concettuale del "Machiavellismo prima di Machiavelli" l'articolo mette in evidenza come nell'Italia rinascimentali fosse pronunciata la tendenza all'affermazione di quelle che Riccardo Fubini chiamava "audacissime affermazioni di sovranità". Il Mezzogiorno - ovvero lo spazio politico del Regno di Napoli - non fu estraneo a queste dinamiche. E il saggio le considera con riferimento all'esperienza dell'insieme dei domini di Giovanni Antonio Orsini del Balzo, principe di Taranto, conte di Lecce, e signore di un vasto aggregato feudale nel Regno, con aspirazioni alla sovranità