New perspectives in the ultrafast spectroscopy of many-body excitations in correlated materials

Ultrafast spectroscopies constitute a fundamental tool to investigate the dynamics of non-equilibrium many-body states in correlated materials. Two-pulses (pump-probe) experiments have shed new light on the interplay between high-energy electronic excitations and the emerging low-energy properties, such as superconductivity and charge-order, in many interesting materials. Here we will review some recent results on copper oxides and we will propose the use of high-resolution multi-dimensional techniques to investigate the decoherence processes of optical excitations in these systems. This novel piece of information is expected to open a new route toward the understanding of the fundamental interactions that lead to the exotic electronic and magnetic properties of correlated materials.Comment: Invited by S.I.F. To appear in Nuovo Cimento C. 7 pages, 4 figure

Intensity of competition and market structure in the Italian banking industry

The aim of this paper is to test the predictions of Sutton's model of independent submarkets for the Italian retail banking industry. This industry, in fact, can be viewed as made of a large number of local markets corresponding to different geographical locations. In order to do that, I first develop a model of endogenous mergers that shows how the number of firms is determined by the initial number of firms, by the intensity of competition, and by the degree of product differentiation, and how this in turn affects the one-firm concentration index. Then, in the second part, the number of banks in each submarket is estimated using a truncated model and a Poisson model. The size of the submarkets turned out to be at most provincial. Finally, the one-firm concentration ratio of each province is regressed on the number of banks, also in interaction with market size variables. As argued by Sutton for industries with exogenous sunk costs, a stronger and negative relationship is found as the market becomes larger.exogenous sunk costs, intensity of competition, concentration, truncated and Poisson models

Risk sharing and firm size: theory and international evidence

This paper investigates the relationship between financial development and firm size. The model shows that the efficiency of the financial system, measured by the level of monitoring costs, affects the extent of risk sharing within an economy and through this channel the availability of external finance to growing firms. If the provision of finance to projects is concentrated in few individuals and firm shocks are idiosyncratic, the risk premium is likely to rise with the amount of funds firms demand. As a consequence, keeping constant the level of opacity and risk, firms with better growth opportunities face higher costs of external finance in countries where the financial system does not favor risk sharing; this limits firm size. Empirical evidence is also provided. Financial constraints appear more stringent for firms whose optimal size is larger in countries where the financial system is less developed.risk sharing; firm size; financial constraints; financial development

Do Better Institutions Mitigate Agency Problems? Evidence from Corporate Finance Choices

This paper examines how firm characteristics, the legal system and financial development affect corporate finance decisions using a novel and unexplored data set containing balance sheet information for listed and unlisted companies. Contrary to the previous literature, by using data on unlisted companies of small dimension, the paper shows that institutions play an important role in determining the extent of agency problems in corporate finance decisions. In particular, it emerges that in countries with good accounting standards and above-average creditor protection, it is easier for firms investing in intangible assets to obtain loans. Therefore, institutions that are capable of effectively protecting lenders are good substitutes for collateral. The protection of creditor rights is also important for guaranteeing access to long-term debt for firms operating in sectors with highly volatile returns. In contrast, if the law does not guarantee creditor rights sufficiently, lenders prefer to issue short-term debt because they can use the threat not to renew the loan to limit entrepreneurs' opportunistic behavior. In this case, inefficiencies due to the excessive liquidation of projects in temporary difficulty may arise. Ceteris paribus, firms are more leveraged in countries where the stock market is less developed. Moreover, unlisted firms appear systematically more indebted even after controlling for firm characteristics, such as profitability, size and the ability to provide collateral. Finally, institutions, which favor creditor rights and ensure stricter enforcement, are associated with higher leverage, but also with greater availability of long-term debt.leverage, debt maturity, agency problems, enforcement, creditor rights

Relationship Lending and Firm Innovativeness

This study investigates the effects of relationship lending on firm innovativeness using a panel of Italian manufacturing firms. In order to disentangle the impact of bank ties on the discovery phase from that in the introduction phase of new technologies, the analysis proceeds in two steps, estimating two distinct equations for each phase. As there are conflicting theoretical predictions on the effects of the various sources of funding in the different stages of the innovative process, this study provides results for small and high-tech firms, so as to control for firm heterogeneity, relying on both cross-section and panel data techniques. Results suggest that for small firms, banks do not carry out a sophisticated intervention at the stage of development of new technologies, playing their traditional role of financing investments of constrained firms. Differently, relationship banks do play an important role in both phases for high-tech firms.Credit relationship;external financing;bank competition

Second-generation adolescents’ competencies and the role of integration policies

Immigration into the OECD countries has seen a sharp increase since the middle of the 1980s, even if not at a constant rate. Integration policies are a fundamental tool to help the newly arrived to integrate and assimilate with the native population. While the literature on the immigrants’ integration level is very rich for settlement countries (USA, Canada, Australia and New Zealand) and for the few European countries that have a long tradition of immigration (Germany, UK, France), very little is yet known about other European economies that have only recently become destination countries. Indeed, the availability of data has made difficult to carry out comparative analysis of the integration process of immigrants in most of the EU countries, particularly for the second-generation. This research wants to fill this gap, analysing the role of the socio-economic background in the educational outcome of immigrants. Furthermore, we demonstrate how the effect of the socio-economic background is more or less pronounced in different EU countries that adopt different integration policies and have different education systems. In this work, we concentrate on second-generation adolescents and compare their performances with that of native adolescents and with that of first generation adolescents. The chosen indicator is the score obtained in the 2012 PISA test by each student (native, first and second-generation immigrant) in reading. We compare the results obtained for each of the EU15 member states and for the settlement countries. The results, in line with the prevalent literature, show a strong impact of the socio-economic background on the immigrant adolescents’ performances. The effect is weaker in those countries where the integration policies concern disadvantaged children since an early age

HFE and transferrin directly compete for transferrin receptor in solution and at the cell surface

Transferrin receptor (TfR) is a dimeric cell surface protein that binds both the serum iron transport protein transferrin (Fe-Tf) and HFE, the protein mutated in patients with the iron overload disorder hereditary hemochromatosis. HFE and Fe-Tf can bind simultaneously to TfR to form a ternary complex, but HFE binding to TfR lowers the apparent affinity of the Fe-Tf/TfR interaction. This apparent affinity reduction could result from direct competition between HFE and Fe-Tf for their overlapping binding sites on each TfR polypeptide chain, from negative cooperativity, or from a combination of both. To explore the mechanism of the affinity reduction, we constructed a heterodimeric TfR that contains mutations such that one TfR chain binds only HFE and the other binds only Fe-Tf. Binding studies using a heterodimeric form of soluble TfR demonstrate that TfR does not exhibit cooperativity in heterotropic ligand binding, suggesting that some or all of the effects of HFE on iron homeostasis result from competition with Fe-Tf for TfR binding. Experiments using transfected cell lines demonstrate a physiological role for this competition in altering HFE trafficking patterns

Financial integration and entrepreneurial activity: evidence from foreign bank entry in emerging markets

An extensive empirical literature has documented the positive growth effects of equity market liberalization. However, this line of research ignores the impact of financial integration on a category of firms crucial for economic development, i.e. the small entrepreneurial firms. This paper aims to fill this void. We employ a large panel containing almost 60,000 firm–year observations on listed and unlisted companies in Eastern European economies to assess the differential impact of foreign bank lending on firm growth and financing. Foreign lending stimulates growth in firm sales, assets, and leverage, but the effect is dampened for small firms. We also find that firms started during the transition period of 1989-1993 – arguably the most connected businesses – benefit least from foreign bank entry. This finding suggests that foreign banks can help mitigate connected lending problems and improve capital allocation. JEL Classification: G21, L11, L14competition, emerging markets, foreign bank lending, lending relationships

Numerical study of laminar magneto-convection in a differentially heated square duct

Magnetohydrodynamic pressure drops are one of the main issues for liquid metal blanket in fusion reactors. Minimize the fluid velocity at few millimeters per second is one strategy that can be employed to address the problem. For such low velocities, buoyant forces can effectively contribute to drive the flow and therefore must be considered in the blanket design. In order to do so, a CFD code able to represent magneto-convective phenomena is required. This work aims to gauge the capability of ANSYS© CFX-15 to solve such cases. The laminar flow in a differentially heated duct was selected as validation benchmark. A horizontal and uniform magnetic field was imposed over a square duct with a linear and constant temperature gradient perpendicular to the field. The fully developed flow was analyzed for Gr = 10^5 and Hartmann number (M) ranging from 10^2 to 10^3. Both insulating and conducting duct walls were considered. Strong dampening of the flow in the center of the duct was observed, whereas high velocity jets appeared close to the walls parallel to the magnetic field. The numerical results were validated against theoretical and numerical results founding an excellent agreement

The role of reciprocation in social network formation, with an application to blogging

This paper deals with the role of reciprocation in the formation of individuals' social networks. We follow the activity of a panel of bloggers over more than a year and investigate the extent to which initiating a relation brings about its reciprocation. We adapt a standard capital investment model to study how reciprocation affects the build-up of the individual social capital of bloggers, as measured by their links and interactions with others. This allows us to measure the role of content production and relationship building in the dynamics of online social networks and to distinguish between the social networking and media aspects of blogging.Blogs, Friendship, LiveJournal, Reciprocation, Social Capital, Social Networks