Evolution of the cluster abundance in non-Gaussian models

We carry out N-body simulations of several non-Gaussian structure formation models, including Peebles' isocurvature cold dark matter model, cosmic string models, and a model with primordial voids. We compare the evolution of the cluster mass function in these simulations with that predicted by a modified version of the Press-Schechter formalism. We find that the Press-Schechter formula can accurately fit the cluster evolution over a wide range of redshifts for all of the models considered, with typical errors in the mass function of less than 25%, considerably smaller than the amount by which predictions for different models may differ. This work demonstrates that the Press-Schechter formalism can be used to place strong model independent constraints on non-Gaussianity in the universe.Comment: 11 pages, 12 postscipt figure

Transactional sex as a response to risk in western Kenya

Formal and informal commercial sex work is a way of life for many poor women in developing countries. Though sex workers have long been identified as crucial in affecting the spread of HIV/AIDS, particularly in Sub-Saharan Africa, the nature of sex-for-money transactions remains poorly understood. Using a unique panel dataset constructed from 192 self-reported sex worker diaries which include detailed information on sexual behavior, labor supply, and health shocks, the authors find that sex workers adjust their supply of risky, better compensated sex to cope with unexpected health shocks, exposing themselves to increased risk of HIV infection. In particular, women are 3.1 percent more likely to see a client, 21.2 percent more likely to have anal sex, and 19.1 percent more likely to have unprotected sex on days in which a household member falls ill. Women also increase their supply of risky sex on days after missing work due to symptoms from a sexually transmitted infection. Given that HIV prevalence has been estimated at 9.8 percent in this part of Kenya, these behavioral responses entail significant health risks for sex workers and their partners, and suggest that sex workers are unable to cope with risk through other formal or informal consumption smoothing mechanisms.Population Policies,Adolescent Health,Gender and Health,Disease Control&Prevention,Health Monitoring&Evaluation

Savings Constraints and Microenterprise Development: Evidence from a Field Experiment in Kenya

Does limited access to formal savings services impede business growth in poor countries? To shed light on this question, we randomized access to non-interest-bearing bank accounts among two types of self-employed individuals in rural Kenya: market vendors (who are mostly women) and men working as bicycle-taxi drivers. Despite large withdrawal fees, a substantial share of market women used the accounts, were able to save more, and increased their productive investment and private expenditures. We see no impact for bicycle-taxi drivers. These results imply significant barriers to savings and investment for market women in our study context. Further work is needed to understand what those barriers are, and to test whether the results generalize to other types of businesses or individuals.

Risk-coping through sexual networks : evidence from client transfers in Kenya

Why do women engage in transactional sex? While much of the explanation is that sex-for-money pays more than other jobs, this paper uses a unique panel dataset constructed from 192 self-reported diaries of sex workers in Western Kenya to show that women who supply transactional sex develop relationships with regular clients, and that these clients send transfers in response to negative income shocks. Regular clients are the primary source of inter-person insurance that women receive, and women report in a separate survey that client transfers are an important reason that they participate in the market.Population Policies,Gender and Law,Adolescent Health,Gender and Health,Population&Development

Why Don't the Poor Save More? Evidence from Health Savings Experiments

Using data from a field experiment in Kenya, we document that providing individuals with simple informal savings technologies can substantially increase investment in preventative health and reduce vulnerability to health shocks. Simply providing a safe place to keep money was sufficient to increase health savings, through a mental accounting effect. Adding an earmarking feature was only helpful when funds were put towards emergencies; earmarking for preventative health reduced savings on average, because the liquidity cost of tying up money was too great. Providing social pressure and credit through a ROSCA-based savings scheme had very large effects.

The Opie Recordings: What’s Left to be Heard?

This chapter presents an analysis of selected recordings from the Opie Collection of Children's Games in the National Sound Archive. It contextualises them with an account of the Opies' research approach, and identifies three themes emerging from the recordings which are not found in published work by the Opies. These are: the strong rleatinoship between children's media cultures and traditional play cultures; more extensive variation of words and music in the singing games; and more extreme examples of obscene and scatological rhymes

Diffusion of particles with short-range interactions

A system of interacting Brownian particles subject to short-range repulsive potentials is considered. A continuum description in the form of a nonlinear diffusion equation is derived systematically in the dilute limit using the method of matched asymptotic expansions. Numerical simulations are performed to compare the results of the model with those of the commonly used mean-field and Kirkwood-superposition approximations, as well as with Monte Carlo simulation of the stochastic particle system, for various interaction potentials. Our approach works best for very repulsive short-range potentials, while the mean-field approximation is suitable for long-range interactions. The Kirkwood superposition approximation provides an accurate description for both short- and long-range potentials, but is considerably more computationally intensive

Land Reform and the Political Organization of Agriculture

The modern theory of agrarian organization has studied how the economic environment determines organizational form under the assumption of stable property rights to land. The political economy literature has modelled the endogenous determination of property rights. In this paper we propose a model in which the economic organization of agriculture and the political equilibrium determining the distribution of property rights are jointly determined. In particular, because the form of organization may affect the probability and distribution of beneÞts from agrarian reform, it may be determined in anticipation of this impact. The model offers a reason for why tenancy, despite its economic advantages has been so little used in countries where agrarian reform is a salient political issue. We argue that this in particular helps to understand the dearth of tenancy and the relative failure of land reform in Latin America.Agrarian Organization, Political Economy, Land Reform

Independent external review: The role of CIAT in the Pan-Africa Bean Research Alliance

The purpose of this center-commissioned review was to establish the extent to which CIAT assumes a leading role in PABRA, recognizing that CIAT has been involved in bean research in Africa for 30 years and that its role has evolved as PABRA and associated partnerships have evolved. PABRA is complex because of its reach, covering activities related to bean breeding and research, ICM, nutrition, seed systems, gender and markets in diverse geographic regions. In total PABRA has over 350 partners throughout Africa and beyond. PABRA is a partnership and the essence of CIAT’s role in PABRA is that of a facilitator, assisting with priority setting, planning and division of responsibilities. In addition, CIAT has provided bean germplasm and technical assistance throughout the duration of PABRA. It is a trusted partner that provides support without assuming all the responsibilities for managing PABRA