Credit Cycles in a OLG Economy with Money and Bequest

In this paper we develop an extended version of the original Kiyotaki and Moore's model ("Credit Cycles" Journal of Political Economy, vol. 105, no 2, April 1997)(hereafter KM) using an overlapping generation structure instead of the assumption of infinitely lived agents adopted by the authors. In each period the population consists of two classes of heterogeneous interacting agents, in particular: a financially constrained young agent (young farmer), a financially constrained old agent (old farmer), an unconstrained young agent (young gatherer), an unconstrained old agent (old gatherer). By assumption each young agent is endowed with one unit of labour. Heterogeneity is introduced in the model by assuming that each class of agents use different technologies to pro- duce the same non durable good. If we study the effect of a technological shock it is possible to demonstrate that its effects are persistent over time in fact the mechanism that it induces is the reallocation the durable asset ("land")among agents. As in KM we develop a dynamic model in which the durable asset is not only an input for production processes but also collateralizable wealth to secure lenders from the risk of borrowers'default. In a context of intergenerational altruism, old agents leave a bequest to their offspring. Money is a means of payment and a reserve of value because it enables to access consumption in old age. For simplicity we assume that preferences are defined over consumption and bequest of the agent when old. Money plays two different and contrasting roles with respect to landholding. On the one hand, given the bequest, the higher the amount of money the young wants to hold, the lower landholding. On the other hand the higher the money of the old, the higher the resources available to him and the higher bequest and landholding. We study the complex dynamics of the allocation of land to farmers and gatherers - which determines aggregate output - and of the price of the durable asset. If a policy move does not change the ratio of money of the farmer and of the gatherer, i.e. if the central bank changes the rates of growth of the two monetary aggregates by the same amount, monetary policy is superneutral, i.e. the allocation of land to the farmer and to the gatherer does not change, real variables are unaffected and the only e¤ect of the policy move is an increase in the rate of inflation, which is pinned down to the (uniform) rate of change of money, and of the nominal interest rate. If, on the other hand, the move is differentiated, i.e. the central bank changes the rates of growth of the two monetary aggregates by different amounts so that the rates of growth are heterogeneous, money is not superneutral, i.e. the allocation of land changes and real variables are permanently affected, even if the rates of growth of the two aggregates go back to the original value afterwardsCredit Cycles, monetary policy

Borrowing constraints and complex dynamics in an OLG framework

In this paper we model an OLG economy à la Kiyotaki and Moore whose novel feature is the role of money as a store of value and of bequest as a source of funds to be "invested" in landholding. The dynamics generated by the model are generally characterized by irregular cyclical trajectories and, under special con.guration of the parameters, a strange attractor appears. In this setting, an expansionary monetary policy may have a stabilizing role due to the interaction between money holding and the accumulation of borrowers' net worth

Cancer-driven dynamics of immune cells in a microfluidic environment

Scope of the present work is to frame into a rigorous, quantitative scaffold - stemmed from stochastic process theory - two sets of experiments designed to infer the spontaneous organization of leukocytes against cancer cells, namely mice splenocytes vs. B16 mouse tumor cells, and embedded in an "ad hoc" microfluidic environment developed on a LabOnChip technology. In the former, splenocytes from knocked out (KO) mice engineered to silence the transcription factor IRF-8, crucial for the development and function of several immune populations, were used. In this case lymphocytes and cancer cells exhibited a poor reciprocal exchange, resulting in the inability of coordinating or mounting an effective immune response against melanoma. In the second class of tests, wild type (WT) splenocytes were able to interact with and to coordinate a response against the tumor cells through physical interaction. The environment where cells moved was built of by two different chambers, containing respectively melanoma cells and splenocytes, connected by capillary migration channels allowing leucocytes to migrate from their chamber toward the melanoma one. We collected and analyzed data on the motility of the cells and found that the first ensemble of IRF-8 KO cells performed pure uncorrelated random walks, while WT splenocytes were able to make singular drifted random walks, that, averaged over the ensemble of cells, collapsed on a straight ballistic motion for the system as a whole. At a finer level of investigation, we found that IRF-8 KO splenocytes moved rather uniformly since their step lengths were exponentially distributed, while WT counterpart displayed a qualitatively broader motion as their step lengths along the direction of the melanoma were log-normally distributed

Global and local determinacy in a one-step forward looking New Keynesian model

In this paper we consider a New Keynesian model for optimal monetary policy in a staggered fashion. We provide the relations of a non linear model of general economic equilibrium, implementing a suitable Taylor-type interest rate rule. We characterize the conditions that guarantee local determinacy and explore conditions under which local bifurcations of the target equilibrium may occur. Afterwards, we argue how local determinacy might be associated with global indeterminacy, providing some numerical examples.Nonlinear model Taylor rule Global determinacy Local bifurcation

Endogeneous Labor Supply, Borrowing Constraint and Credit Cycles

We investigate Matsuyama's (Econometrica, 72, pp. 853-84, 2004) model modi- fied only to include endogenous and forward looking labor supply decision. Young agents supply one unit of labor endowment elastically to a competitive labor market. While, old agents of ex-ante identical individuals are divided in equi- librium into depositors and entrepreneurs. Depositors lend funds in the form of interest bearing loans, while entrepreneurs borrow funds in the competitive credit market. We emphasize the interaction between credit and labor markets and show the possibility of occurrence of multiple steady states, local and global indeterminacy, and endogenous fluctuations. When young agents become optimistic about the future deposit rate then they decide to work harder and invest more. Countercyclical borrowing constraint will help agents to fulfill their initial optimistic expectations, because the next period credit volume and deposit rate can increase simultaneously. By conducting global bifurcation analysis, we show that credit cycles can occur through a self- fulfilling expectation mechanism. History-versus-expectations considerations can exist and escape from underdevelopment as well as fall into poverty can to be a self-fulfilling prophecy.Borrowing constraint; Credit cycles; Elastic labor supply; Endogenous fluctuations; Self-fulfilling expectations.