Wealth Accumulation and Activity Choice Evolution Among Amazonian Forest Peasant Households

This paper examines investment and livelihood decisions among forest peasant households in the Amazonian floodplain. A dynamic household model of multiple asset accumulation and activity choice under risk and credit constraints is developed by incorporating natural resource use and human capital evolution. Asset portfolios and sectoral incomes are estimated and then simulated to investigate the endowment and lifecycle dependency as well as the convergence/divergence of asset accumulation and corresponding activity choices. Physical asset endowment (especially land) and different human capital evolutions across activities help to explain forest peasants' livelihood choices, distinctive asset portfolios, and divergent income outcomes over the lifecycle.

Smoothing Income against Crop Flood Losses in Amazonia: Rain Forest or Rivers as a Safety Net

This article examines the role of ex post labor supply in smoothing income in response to crop losses caused by large floods among riverine households in the Peruvian Amazon, where rich environmental endowments permit a variety of resource extractive activities and coping responses. The paper finds that households respond to crop losses primarily by intensifying fishing effort not by relying on gathering of non-timber forest products, hunting, or asset liquidation. This ex post labor adjustment helps to smooth total income against small crop losses but less well against large crop losses. Both relatively non-poor households with better fishing capital and poor young households with a physical labor advantage employ this natural insurance in rivers.

An hbar-expansion of the Toda hierarchy: a recursive construction of solutions

A construction of general solutions of the \hbar-dependent Toda hierarchy is presented. The construction is based on a Riemann-Hilbert problem for the pairs (L,M) and (\bar L,\bar M) of Lax and Orlov-Schulman operators. This Riemann-Hilbert problem is translated to the language of the dressing operators W and \bar W. The dressing operators are set in an exponential form as W = e^{X/\hbar} and \bar W = e^{\phi/\hbar}e^{\bar X/\hbar}, and the auxiliary operators X,\bar X and the function \phi are assumed to have \hbar-expansions X = X_0 + \hbar X_1 + ..., \bar X = \bar X_0 + \hbar\bar X_1 + ... and \phi = \phi_0 + \hbar\phi_1 + .... The coefficients of these expansions turn out to satisfy a set of recursion relations. X,\bar X and \phi are recursively determined by these relations. Moreover, the associated wave functions are shown to have the WKB form \Psi = e^{S/\hbar} and \bar\Psi = e^{\bar S/\hbar}, which leads to an \hbar-expansion of the logarithm of the tau function.Comment: 37 pages, no figures. arXiv admin note: substantial text overlap with arXiv:0912.486

Quantum and Classical Aspects of Deformed c=1c=1 Strings.

The quantum and classical aspects of a deformed $c=1$ matrix model proposed by Jevicki and Yoneya are studied. String equations are formulated in the framework of Toda lattice hierarchy. The Whittaker functions now play the role of generalized Airy functions in $c<1$ strings. This matrix model has two distinct parameters. Identification of the string coupling constant is thereby not unique, and leads to several different perturbative interpretations of this model as a string theory. Two such possible interpretations are examined. In both cases, the classical limit of the string equations, which turns out to give a formal solution of Polchinski's scattering equations, shows that the classical scattering amplitudes of massless tachyons are insensitive to deformations of the parameters in the matrix model.Comment: 52 pages, Latex

hbar-Dependent KP hierarchy

This is a summary of a recursive construction of solutions of the hbar-dependent KP hierarchy. We give recursion relations for the coefficients X_n of an hbar-expansion of the operator X = X_0 + \hbar X_1 + \hbar^2 X_2 + ... for which the dressing operator W is expressed in the exponential form W = \exp(X/\hbar). The asymptotic behaviours of (the logarithm of) the wave function and the tau function are also considered.Comment: 12 pages, contribution to the Proceedings of the "International Workshop on Classical and Quantum Integrable Systems 2011" (January 24-27, 2011 Protvino, Russia

Investigation of electron temperature gradient driven micro-reconnecting modes in toroidal high-energy plasmas

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (p. 43).Experiments carried out with magnetically confined, high temperature plasmas have revealed important effects that have yet to be justified by existing theory. In particular, there arises an anomalous particle inflow in the central region of the plasma column. Experimental evidence suggests that this particle transport results from the excitation of unstable, short wavelength modes driven by the electron temperature gradient, but the validity of the existing theory is limited to the edge of the plasma column. This thesis investigates the question of how microscopic, electron temperature gradient driven, micro-reconnecting modes may collectively give rise to particle inflow in the central region of the plasma column by examining solutions to the mode dispersion relation. Derivations of micro-reconnecting modes in both fluid and kinetic theory are presented, and the resulting dispersion relation is analyzed.by Keven T. Takasaki.S.B

Toda Lattice Hierarchy and Generalized String Equations

String equations of the $p$-th generalized Kontsevich model and the compactified $c = 1$ string theory are re-examined in the language of the Toda lattice hierarchy. As opposed to a hypothesis postulated in the literature, the generalized Kontsevich model at $p = -1$ does not coincide with the $c = 1$ string theory at self-dual radius. A broader family of solutions of the Toda lattice hierarchy including these models are constructed, and shown to satisfy generalized string equations. The status of a variety of $c \le 1$ string models is discussed in this new framework.Comment: 35pages, LaTeX Errors are corrected in Eqs. (2.21), (2.36), (2.33), (3.3), (5.10), (6.1), sentences after (3.19) and theorem 5. A few references are update