A Model for the Schottky Anomaly in Metallic Nd2−yCeyCuO4Nd_{2-y}Ce_{y}CuO_{4}

We present a simple model for the doped compound $Nd_{2-y}Ce_{y}CuO_{4}$, in order to explain some recent experimental results on the latter. Within a Hartree-Fock context, we start from an impurity Anderson-like model and consider the magnetic splitting of the $Nd$-$4f$ ground state Kramers doublet due to exchange interactions with the ordered $Cu$ moments. Our results are in very good agreement with the experimental data, yielding a Schottky anomaly peak for the specific heat that reduces its amplitude, broadens and shifts to lower temperatures, upon $Ce$ doping. For overdoped compounds at low temperatures, the specific heat behaves linearly and the magnetic susceptibility is constant. A smooth transition from this Fermi liquid like behavior ocurrs as temperature is increased and at high temperatures the susceptibility exhibits a Curie-like behavior. Finally, we discuss some improvements our model is amenable to incorporate.Comment: 7 pages, 5 figures, and 13 reference

A Model of TFP

This paper proposes an aggregative model of Total Factor Productivity (TFP) in the spirit of Houthakker (1955-1956). It considers a frictional labor market where production units are subject to idiosyncratic shocks and jobs are created and destroyed as in Mortensen and Pissarides (1994). An aggregate production function is derived by aggregating across production units in equilibrium. The level of TFP is explicitly shown to depend on the underlying distribution of shocks as well as on all the characteristics of the labor market as summarize by the job-destruction decision. The model is also used to study the effects of labor-market policies on the level of measured TFP.

New massive bigravity cosmologies with double matter coupling

We study a previously largely unexplored branch of homogeneous and isotropic background solutions in ghost-free massive bigravity with consistent double matter coupling. For a certain family of parameters we find `self-inflated' FLRW cosmologies, i.e. solutions with an accelerated early-time period during the radiation-dominated era. In addition, these solutions also display an accelerated late-time period closely mimicking GR with a cosmological constant. Interestingly, within this family, the particular case of $\beta_1=\beta_3=0$ gives bouncing cosmologies, where there is an infinite contracting past, a non-zero minimum value of the scale factor at the bounce, and an infinite expanding future.Comment: Last version includes minor changes to text and reference

Liquidity in asset markets with search frictions

We develop a search-theoretic model of financial intermediation and use it to study how trading frictions affect the distribution of asset holdings, asset prices, efficiency and standard measures of liquidity. A distinctive feature of our theory is that it allows for unrestricted asset holdings, so market participants can accommodate trading frictions by adjusting their asset positions. We show that these individual responses of asset demands constitute a fundamental feature of illiquid markets: they are a key determinant of bid-ask spreads, trade volume and trading delays—all the dimensions of market liquidity that search-based theories seek to explain.Liquidity (Economics) ; Over-the-counter markets ; Investments

Liquidity in asset markets with search frictions

We develop a search-theoretic model of financial intermediation and use it to study how trading frictions affect the distribution of asset holdings, asset prices, efficiency, and standard measures of liquidity. A distinctive feature of our theory is that it allows for unrestricted asset holdings, so market participants can accommodate trading frictions by adjusting their asset positions. We show that these individual responses of asset demands constitute a fundamental feature of illiquid markets: they are a key determinant of bid-ask spreads, trade volume, and trading delays - all the dimensions of market liquidity that search-based theories seek to explain. ; This paper is an extension of Ricardo Lagos's work while he was in the Research Department of the Federal Reserve Bank of Minneapolis.Liquidity (Economics) ; Search theory

Lagos Poster

Poster promoting the Lagos lectur

Money and capital as competing media of exchange

We construct a model where capital competes with fiat money as a medium of exchange, and we establish conditions on fundamentals under which fiat money can be both valued and socially beneficial. When the socially efficient stock of capital is too low to provide the liquidity agents need, they overaccumulate productive assets to use as media of exchange. When this is the case, there exists a monetary equilibrium that dominates the nonmonetary one in terms of welfare. Under the Friedman Rule, fiat money provides just enough liquidity so that agents choose to accumulate the same capital stock a social planner would.Capital ; Liquidity (Economics)