AMS Acta
(4.910 recursos)
Repository of the University of Bologna.
Mostrando recursos 1 - 20 de 466
1.
La soluzione dell'enigma di Piero della Francesca - Molari, Pier Gabriele
L’interpretazione dell’iconografia della Flagellazione di Piero della Francesca è dibattuta da lungo tempo e non ha trovato fino ad ora una risposta definitiva malgrado vari tentativi.
In questo saggio, il dipinto viene associato alla tavola di Brera detta di San Bernardino ed alle tavolette della Galleria degli Uffizi di Firenze con i ritratti dei signori di Montefeltro pensando ad un'unica opera realizzata per la meditazione di Federico da Montefeltro.
Questo inedito e forse ardito accostamento pone l'insieme dei quattro dipinti sotto la stessa ottica e ne permette una definitiva interpretazione iconografica come pure una datazione certa.
Collocando poi l’insieme delle tavole nel...
2.
Metodi per la ricostruzione della posizione d'impatto per immagini planari provenienti da una gamma camera - Cornelio, Anastasia
La stima della posizione di interazione dei fotoni su una gamma camera per medicina nucleare presenta tipicamente dei problemi vicino ai bordi del rivelatore. Questo fenomeno è dovuto sicuramente alla perdita dei contributi delle code delle distribuzioni di luce che, avvicinandosi ai bordi, cadono al di fuori del rivelatore stesso.
In questo lavoro si analizzano e si confrontano i risultati di vari metodi per cercare di migliorare l'errore che si commette nel calcolo della posizione d'impatto.
3.
Dynamic R&D with Spillovers: Competition vs Cooperation - Cellini, Roberto; Lambertini, Luca
We investigate dynamic R&D for process innovation in a duopoly where firms may either undertake independent ventures or form a cartel for cost-reducing R&D investments. By comparing the profit and welfare perfomances of the two settings in steady state, we show that private and social incentives towards R&D cooperation coincide for all admissible levels of the technological spillovers characterising innovative activity. This results stems from smoothing the investment reffort over the time horizon of the game.
4.
Would you like to enter first with a low-quality good? - Lambertini, Luca; Tedeschi, Piero
Using a two-period duopoly model with vertical differentiation, we show that there exists a unique subgame perfect equilibrium where the first entrant supplies a lower quality and gains higher profits than the second entrant. We also prove that this entry sequence is also socially efficient.
5.
Experimentation and Disappointment - Luppi, Barbara
We depart from the classic setting of bandit problems by endowing the agent with a disappointment-elation utility function. The disutility of a loss is assumed to be greater than the elation associated with same-size gain, according to Kahneman-Tversky findings on the attitude of agents towards a change in wealth. We characterise the optimal experimentation strategy of an agent in a two-armed bandit problem setting with infinite horizon and we derive an existence theorem, specifying a condition on the disappointment aversion parameter. The model, solved in closed form in a one-armed bandit setting, shows that an agent who feels disappointment experiments...
6.
Sequential Entry in a Vertically Differentiated Duopoly - Lambertini, Luca; Tedeschi, Piero
We analyse a model of vertical differentiation focusing on the trade-off between entering early and exploiting monopoly power with a low quality, versus waiting and enjoying a dominant market position with a superior product. We show that there exists a unique equilibrium where the leader enters with a lower quality than the follower, for low discount factors, for high costs of quality and for low consumers’ willingness to pay for quality.
7.
Price indices for artists - A proposal - Candela, Guido; Figini, Paolo; Scorcu, Antonello E.
This paper proposes a price index for artists based on the ratio between the average market price and the average estimated price of the paintings sold by an artist each year, adjusted for market dynamics. We apply this methodology to a group of selected artists and schools drawing from a database including auction prices and estimated prices of paintings presented in auctions world wide between 1990 and 2001. A comparison with quality unadjusted and hedonic indices is also proposed.
8.
Quality and Advertising in a Dynamic Duopoly - Colombo, Luca; Lambertini, Luca
We investigate a differential duopoly game where each firm, through capital accumulation over time, may invest both in persuasive advertising campaigns aimed at increasing the willingness to pay of consumers and in an R&D process aimed at increasing the level of own product quality. In contrast with the acquired wisdom based on static models, the firm providing the market with the inferior variety may earn higher profits than the rival. More than this, we show that there exists a range of parameters wherein the low quality firm commands monopoly power.
9.
The issue of time inconsistency revisited as an extended game - Cellini, Roberto; Lambertini, Luca
We reformulate the monetary policy model of Barro and Gordon (1983a) by using an extended game with observable delay where the hierarchy of play between the central bank and the private sector is endogenous. This allows us to endogenise the institutional setup wherein the monetary policy game takes place. We show that positive inflation may be observed due to mixed strategies rather than time inconsistency.
10.
Endogeneous outsourcing and vertical integration with process R&D - Rossini, Gianpaolo; Lambertini, Luca
According to received literature, vertical integration may enjoy a social superiority due to the ability to internalize the externality that goes back from the pricing policy of the downstream firm to the profits of the upstream firm. We challenge this result introducing process R&D in a broad set of scenarios with vertically symmetric and asymmetric R&D commitments. In some of these contexts a reversed sequence of socially desirable vertical arrangements arises, making out-sourcing superior. In other circumstances disintegration is privately superior but socially in efficient. Finally, vertically asymmetric costs of R&D are considered to allow for a wider range of...
11.
The skill bias effect of technological and organisational change: evidence and policy implications - Piva, Mariacristina; Santarelli, Enrico; Vivarelli, Marco
Previous empirical literature has shown that technological change can be considered the main cause of the skill bias (increase in the number of high skilled workers) exhibited by manufacturing employment in developed countries over the last decades. However, recent papers have also introduced the "Skill Biased Organisational Change" hypothesis. We estimate a SUR model for a sample of 400 Italian manufacturing firms, showing that the upskilling is more a function of the reorganisational strategy than a consequence of technological change alone. Moreover, some evidence of superadditive effects emerges, consistently with the theoretical hypothesis of a coevolution of technology and organisation.
12.
Quality of Service in the Congestible Internet: a Differential Game with Capacity Investments - Colombo, Luca
We take a differential game approach to study the dynamic market interaction between two Internet Service Providers (ISP) offering services characterized by different quality levels.Web congestion is accounted for,consisting in the fact that for a given network capacity, i.e. for given amount of resources to be shared, the quality of services decreases with the number of customers. ISP firms, by accumulating capital,may invest in order to increase their own network capacity. In contrast with the acquired wisdom, we prove that there exists an admissible intertemporal parameters subset wherein the low quality firm performs better than the high quality firm in...
13.
The Effects of Minimum Quality Standards on Product Quality - Garella, Paolo G.
In a model where two firms’ products are di¤erentiated both, horizontally and vertically, introduction of a quality standard affects equilibrium quality levels of both firms. The effects, furthermore, depend upon consumers being or not perfectly informed about qualities. Qualities are strategic substitutes and under perfect information only non-innocuous standards, i.e. above the lowest quality in an unregulated equilibrium, change the equilibrium. However, the average quality in the market may go down due to the standard, and total consumers welfare decrease. Under uncertainty, even apparently innocuous standards, below the lowest unregulated equilibrium quality, may alter the equilibrium quality choices.
14.
The Twin Effects of Globalization - Daveri, Francesco; Manasse, Paolo; Serra, Danila
Employees of "globalized" firms face a riskier, but potentially more rewarding, menu of labor market outcomes. We document this neglected trade-off globalization for a sample of Indian manufacturing firms. On the one hand, the employees of firms subject to foreign competition face a more uncertain stream of earnings and riskier employment prospects. On the other, they enjoy a more rapid career and/or have more opportunities to train and upgrade their skills. The negative uncertainty costs and the positive incentive effects of globalization are thus twin to each other. Concentrating on just one side of the coin gives a misleading picture...
15.
Working on the Train? The Role of Technical Progress and rade in Explaining Wage Differentials in Italian Firms - Manasse, Paolo; Stanca, Luca
This paper presents firm-level evidence on the dynamics of the relative demand for non-manual workers in Italian manufacturing during the 1990s. The analysis provides a number of interesting results. First, the rise within firms in the share of non manual workers in both employment and hours worked (within-firm skill upgrading) is the main determinant of the increase in the relative demand for skilled workers. By contrast, demand changes associated to trade have mitigated such a rise by shifting employment away from skill-intensive firms. Second, while the relative number of hours worked by skilled workers within firms has risen, the hourly...
16.
Brain Drain and Fiscal Competition. A theoretical model for the Europe. - Giannoccolo, Pierpaolo
In this paper we study Brain Drain (BD) and Fiscal Competition (FC) in a unified framework for the European Union (EU) specific context. Potential mobility of educated workers can increase the degree of FC through taxation or the provision of public education. An increase in FC can be caused by competition among different jurisdictions that aim to attract educated workers. When the importance of FC increases, then the European States may employ FC as a new policy tool. First, we analyze FC and BD with reference to EU regions. In this instance, the EU may find incentive to control the...
17.
The Harmonization of Technical Barriers to Trade, Innovation and Export Behavior: Theory with an application to EU Environmental Data. - Mantovani, Andrea; Vancauteren, Mark
A key feature of the EU harmonization of technical barriers to trade (TBT’s) is that exporting firms may entail a compliance costs. This paper provides theoretical and empirical work. In a simple Cournot duopoly with trade, we pursue the idea that process R&D has a positive spillover effect (with different intensities) in lowering the compliance cost and investigate the impact of an R&D subsidy. Using a self-constructed database, which specifically identifies sectors where the EU has sought to introduce harmonized environmental regulations, we find evidence that support this prediction of the theory.
18.
Endogenous Transportation Technology in a Cournot Differential Game with Intraindustry Trade - Colombo, Luca; Lambertini, Luca; Mantovani, Andrea
We investigate a dynamic Cournot duopoly with intraindustry trade, where firms invest in R&D to reduce the level of iceberg transportation costs. We adopt both open-loop and closed-loop equilibrium concepts, showing that a unique (saddle point) steady state exists in both cases. In the open-loop model, optimal investments and the resulting efficiency of transportation technology are independent of the relative size of the two countries. On the contrary, in the closed-loop case, a home market effect operates so that thefirm located in the larger country invests more than the rival located in the smaller one. Policy implications are also evaluated.
19.
Gibrat’s law and market selection in the radio, tv & telecommunications equipment industry - Lotti, Francesca; Santarelli, Enrico; Vivarelli, Marco
According to Gibrat’s Law of Proportionate Effect, the growth rate of a given firm is independent of its size at the beginning of the period examined. In contrast to the previous literature on the subject, this paper seeks to test the Law by taking account of both the entry process and the role of survival/failure in reshaping a given population of firms over time. It does so by focusing on the entire population of firms (including newborn ones) in the Italian Radio, TV & Telecommunications equipment industry and tracking them over seven years. Consistently with the previous literature, it finds...
20.
Private incentives to vertical disintegration among firms with heterogeneous objectives - Rossini, Gianpaolo
A vertically integrated monopoly is compared to a decentralized market arrangement where production is segmented. A Labor Managed firm produces an input used by a profit maximizer manufacturerof a final good. Unlike what usually occurs between homogenoeus firms we find circumstances in which the decentralised vertical arrangement is privately superior to the integrated one.
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