Flat currents modulo p in metric spaces and filling radius inequalities

We adapt the theory of currents in metric spaces, as developed by the first-mentioned author in collaboration with B. Kirchheim, to currents with coefficients in Z_p. Building on S. Wenger's work in the orientable case, we obtain isoperimetric inequalities mod(p) in Banach spaces and we apply these inequalities to provide a proof of Gromov's filling radius inequality (and therefore also the systolic inequality) which applies to nonorientable manifolds, as well. With this goal in mind, we use the Ekeland principle to provide quasi-minimizers of the mass mod(p) in the homology class, and use the isoperimetric inequality to give lower bounds on the growth of their mass in balls.Comment: 31 pages, to appear in Commentarii Mathematici Helvetic

Estimation of general Hamiltonian parameters via controlled energy measurements

The quantum Cram\'er-Rao theorem states that the quantum Fisher information (QFI) bounds the best achievable precision in the estimation of a quantum parameter $\xi$. This is true, however, under the assumption that the measurement employed to extract information on $\xi$ are regular, i.e. neither its sample space nor its positive-operator valued elements depend on the (true) value of the parameter. A better performance may be achieved by relaxing this assumption. In the case of a general Hamiltonian parameter, i.e. when the parameter enters the system's Hamiltonian in a non-linear way (making the energy eigenstates and eigenvalues $\xi$-dependent), a family of non-regular measurements, referred to as controlled energy measurements, is naturally available. We perform an analytic optimization of their performance, which enables us to compare the optimal controlled energy measurement with the optimal Braunstein-Caves measurement based on the symmetric logarithmic derivative. As the former may outperform the latter, the ultimate quantum bounds for general Hamiltonian parameters are different than those for phase (shift) parameters. We also discuss in detail a realistic implementation of controlled energy measurements based on the quantum phase estimation algorithm and work out a variety of examples to illustrate our results.Comment: revised and enlarged versio

The Firm as a Dedicated Hierarchy: A Theory of the Origin and Growth of Firms

A fundamental problem entrepreneurs face in the formative stages of their businesses is how to provide incentives for employees to protect, rather than steal, the source of organizational rents. We study how the entrepreneur's response to this problem will determine the organization's internal structure, growth, and its eventual size. In particular, our model suggests large, steep hierarchies will predominate in physical capital intensive industries, and these will typically have seniority-based promotion policies. By contrast, flat hierarchies will be seen in human capital intensive industries. These will have up-or-out promotion systems, where experienced managers either become owners or are fired. Furthermore, flat hierarchies will have more distinctive technologies or cultures than steep hierarchies. The model points to some essential differences between organized hierarchies and markets.

What Do We Know About Capital Structure? Some Evidence from International Data

We investigate the determinants of capital structure choice by analyzing the financing decisions of public firms in the major industrialized countries. At an aggregate level, firm leverage is fairly similar across the G-7 countries. We find that factors identified by previous studies as important in determining the cross- section of capital structure in the U.S. affect firm leverage in other countries as well. However, a deeper examination of the U.S. and foreign evidence suggests that the theoretical underpinnings of the observed correlations are still largely unresolved.

The Great Reversals: The Politics of Financial Development in the 20th Century

We show that the development of the financial sector does not change monotonically over time. In particular, we find that by most measures, countries were more financially developed in 1913 than in 1980 and only recently have they surpassed their 1913 levels. This pattern is inconsistent with most recent theories of why cross-country differences in financial development do not track differences in economic development, since these theories are based upon time-invariant factors, such as a country's legal origin. We propose instead an 'interest group' theory of financial development. Incumbents oppose financial development because it breeds competition. The theory predicts that incumbents' opposition will be weaker when an economy allows both cross-border trade and capital flows. This theory can go some way in accounting for the cross-country differences and the time series variation of financial development.

The Influence of the Financial Revolution on the Nature of Firms

Major technological, regulatory, and institutional changes have made finance more widely available in recent years, amounting to a bone fide 'financial revolution'. In this article, we focus on the impact the financial revolution has had on the way firms are (or should be) organized and managed, and on the policy consequences.

Financial Dependence and Growth

Does finance affect economic growth? A number of studies have identified a positive correlation between the level of development of a country's financial sector and the rate of growth of its per capita income. As has been noted elsewhere, the observed correlation does not necessarily imply a causal relationship. This paper examines whether financial development facilitates economic growth by scrutinizing one rationale for such a relationship; that financial development reduces the costs of external finance to firms. Specifically, we ask whether industrial sectors that are relatively more in need of external finance develop disproportionately faster in countries with more developed financial markets. We find this to be true in a large sample of countries over the 1980s. We show this result is unlikely to be driven by omitted variables, outliers, or reverse causality.