TRANSFORMATION OF FALLOW SYSTEMS UNDER POPULATION PRESSURE

In a fallow-cultivation model with biomass regeneration, we find the population-poverty-degradation linkage via the discount rate: slight increases in the discount rate result in increased cropping frequency and much lower soil fertility. Aggregating gives transitions equation declining in fertility and increasing in the fallow:cultivation ratio.Land Economics/Use,

Bank time deposit rates and market discipline in Poland: the impact of state ownership and deposit insurance reform

This paper examines the impact of ownership structure and changes in the deposit insurance system on the market for bank time deposits in Poland. In an environment of less restrictive bank supervision and a deposit insurance policy that favored state banks, we find depositors exacted a price for risk taking. After a new law increasing coverage for private banks went into effect, however, bank specific variables became less important in explaining differences in deposit interest rates. We report that the three fully guaranteed state banks pay significantly lower rates that private banks. However, other state-owned banks, with the same de jure guarantee as private banks, pay significantly lower rates than private banks, so it appears that depositors treat these state-owned banks as if they have a larger de facto guarantee.Poland ; Deposit insurance

Geographic patterns of land use and land intensity in the Brazilian Amazon

Using census data from the Censo Agropecuario 1995-96, the authors map indicators of current land use, and agricultural productivity across Brazil's Legal Amazon, These data permit geographical resolution about ten times finer than afforded by"municipio"data, used in previous studies. The authors focus on the extent, and productivity of pasture, the dominant land use in Amazonia today. Simple tabulations suggest that most agricultural land in Amazonia yields little private economic value. Nearly ninety percent of agricultural land is either devoted to pasture, or has been out of use for more than four years. About forty percent of the currently used pastureland, has a stocking ratio of less that 0.5 cattle per hectare. Tabulations also show a skewed distribution of land ownership: almost half of Amazonian farmland is located in the one percent of properties that contain more than two thousand hectares. Multivariate analyses relate forest conversion, and pasture productivity to precipitation, soil quality, infrastructure, and market access, proximity to past conversion, and protection status. The authors find precipitation to have a strong deterrent effect on agriculture. The probability that land is currently claimed, or used for agriculture, or intensively stocked with cattle, declines substantially with increasing precipitation levels, holding other factors (such as road access) constant. Proxies for land abandonment are also higher in high rainfall areas. Together these findings suggest that the wetter Western Amazon is inhospitable to exploitation for pasture, using current technologies. On the other hand, land conversion, and stocking rates are positively correlated with proximity to past clearing. This suggests that in the areas of active deforestation in eastern Amazonia, the frontier is not :hollow:, and land use intensifies over time. But this area remains a mosaic of lands with higher, and lower potential agricultural value.Agricultural Knowledge&Information Systems,Climate Change,Wetlands,Water Conservation,Environmental Economics&Policies,Climate Change,Wetlands,Environmental Economics&Policies,Agricultural Knowledge&Information Systems,Forestry

Banking reform in a transition economy: the case of Poland

Polish banks have been weakened by large loan losses and low capital. Recapitalization and better economic conditions have strengthened the industry, but problems remain, especially among some large state-owned banks. Continued improvement of the banking system will require additional domestic or foreign capital to strengthen reserves and to modernize operations.Banks and banking ; Poland

Synchronization of electrically coupled resonate-and-fire neurons

Electrical coupling between neurons is broadly present across brain areas and is typically assumed to synchronize network activity. However, intrinsic properties of the coupled cells can complicate this simple picture. Many cell types with strong electrical coupling have been shown to exhibit resonant properties, and the subthreshold fluctuations arising from resonance are transmitted through electrical synapses in addition to action potentials. Using the theory of weakly coupled oscillators, we explore the effect of both subthreshold and spike-mediated coupling on synchrony in small networks of electrically coupled resonate-and-fire neurons, a hybrid neuron model with linear subthreshold dynamics and discrete post-spike reset. We calculate the phase response curve using an extension of the adjoint method that accounts for the discontinuity in the dynamics. We find that both spikes and resonant subthreshold fluctuations can jointly promote synchronization. The subthreshold contribution is strongest when the voltage exhibits a significant post-spike elevation in voltage, or plateau. Additionally, we show that the geometry of trajectories approaching the spiking threshold causes a "reset-induced shear" effect that can oppose synchrony in the presence of network asymmetry, despite having no effect on the phase-locking of symmetrically coupled pairs

Quantifying the rural-urban gradient in Latin America and the Caribbean

This paper addresses the deceptively simple question: What is the rural population of Latin America and the Caribbean (LAC)? It argues that rurality is a gradient, not a dichotomy, and nominates two dimensions to that gradient: population density and remoteness from large metropolitan areas. It uses geographically referenced population data (from the Gridded Population of the World, version 3) to tabulate the distribution of populations in Latin America and in individual countries by population density and by remoteness. It finds that the popular perception of Latin America as a 75 percent urban continent is misleading. Official census criteria, though inconsistent between countries, tend to classify as"urban"small settlements of less than 2,000 people. Many of these settlements are however embedded in an agriculturally based countryside. The paper finds that about 13 percent of Latin America populations live at ultra-low densities of less than 20 per square kilometer. Essentially these people are more than an hour's distance from a large city, and more than half live more than four hours'distance. A quarter of the population of Latin America is estimated to live at densities below 50, again essentially all of them more than an hour's distance from a large city. Almost half (46 pecent) of Latin America live at population densities below 150 (a conventional threshold for urban areas), and more than 90 percent of this group is at least an hour's distance from a city; about one-third of them (18 percent of the total) are more than four hours distance from a large city.Agricultural Research,Demographics,Health Indicators,,Health Information&Communications Technologies

An Optimal Incentive System For Real Estate Agents

This article presents an alternative system for selling real estate. It overcomes the well-known deficiencies of the percentage commission system. In our system, the agent purchases the property from the seller and simultaneously receives a put option. The put option gives the agent the right to put the property back to the original owner. It is shown that this system has many of the desirable properties of a dealer system, while avoiding some of the problems that are inherent in that system.

Creating markets for habitat conservation when habitats are heterogeneous

A tradable development rights (TDR) program focusing on biodiversity conservation faces a crucial problem defining which areas of habitat should be considered equivalent. Restricting the trading domain to a narrow area could boost the range of biodiversity conserved but could increase the opportunity cost of conservation. The issue is relevant to Brazil, where TDR-like programs are emerging. Current regulations require each rural property to maintain a forest reserve of at least 20 percent, but nascent policies allow some tradability of this obligation. The authors use a simple, spatially explicit model to simulate a hypothetical state-level program. They find that wider trading domains drastically reduce landholder costs of complying with this regulation and result in environmentally preferable landscapes.Wetlands,Environmental Economics&Policies,Banks&Banking Reform,Water Conservation,Climate Change,Forestry,Environmental Economics&Policies,Wetlands,Climate Change,Banks&Banking Reform

An Inverted Teaching Model for a Mechanics of Materials Course

Instructors at Missouri University of Science and Technology have been offering certain sections of a mechanics of materials course in an inverted format for the past two years. In this format, students learn the concepts outside of class, using a textbook, animations and videos developed by the authors, and work on homework either individually or in groups during the optional class time. Students take eight multiple-choice exams and a final exam that is common to both the inverted sections and the more traditional lecture-based sections. Homework in the inverted sections is assigned but not graded. The in-class exams are given in a computer lab, and each student receives an individualized set of questions. Over 1200 students in 18 course sections have participated in either the inverted sections themselves or the other non-traditional sections that preceded the particular format used today. A subset of this group was compared to students in the traditional sections. No statistically significant difference between the two groups was found based on (1) performance on the common final exams or (2) course grade in a structural analysis course. The animations and videos used by students in the inverted sections are available on a class web site. There are 167 animation modules and 230 videos. The animations contain example problems and exercises. The videos are, on average, six minutes in length and cover concepts, demonstrations, problem strategies, problem solutions, and experiments. The authors use Google Analytics to track how much each piece of content is utilized. The website was accessed 46,500 times, and the content, excluding the animations, was used for a total of 12,700 hours during the past 16 months. By tracking how students perform on each multiple-choice question, the authors have developed a concept inventory with numerical rankings from the best to worst understood concepts. Combining this with how much each online resource is utilized, the authors can now target development of future course materials on the least-understood concepts and in the format most preferred by the students. An inverted teaching format would not be appropriate for every college course, but it has helped the authors begin looking at their mechanics of materials course in a more scientific, data-driven manner