Patterns of Aging in Thailand and Cote D'Ivoire

This paper is broadly concerned with the living standards of older people in two contrasting developing countries, Cote d'Ivoire and Thailand. We use a series of household surveys from these two countries to present evidence on factors affecting the living standards of the elderly: living arrangements, labor force participation, illness, urbanization, income and consumption. One of the issues we examine is whether life-cycle patterns of income aid consumption can be detected in the data. The fact that few of the elderly live alone makes it difficult to accurately measure the welfare levels of the elderly, or to make statements about the life-cycle patterns of income aid consumption of individuals. We find that labor force participation and individual income patterns follow the standard life-cycle hump shapes in both countries, but that avenge living standards within households are quite flat over the life-cycle. The data presented suggest that changes in family composition aid living arrangements of the elderly are likely to be more important sources of old-age insurance than asset accumulation.

Job Characteristics and Hours of Work

This paper provides evidence that hours of work are heavily influenced by the particular job which a person holds. The empirical work consists of a comparison of the variance in the change in work hours across time intervals containing a job change with the variance in the change in hours across time periods when the job remains the same. To the extent that workers choose hours and these hours choices are influenced by shifts in individual preferences and resources, the variance in the time change of hours should not depend upon whether the worker has switched jobs. The desire to reduce or increase hours could be acted upon in the current job. On the other hand, if hours are influenced by employer preferences or if job specific characteristics dominate the labor supply decision, then hours changes should be larger when persons change jobs than when they do not. Using the Panel Study of Income Dynamics and the Quality of Employment Survey, we find that hours changes are typically two to four times more variable across jobs than within jobs. This result holds for both men and women and for both quits and layoffs, is obtained for weeks per year, hours per week, and annual hours, andis not sensitive to the use of controls for a set of job characteristics (including the wage) which might influence the level of hours persons wish to supply. The findings are also inconsistent with the view that workers may costlessly adjust hours by changing jobs.The finding that the job has a large influence on work hours suggests that much greater emphasis should be given to demand factors and to job specific labor supply factors in future research on hours of work. The overwhelming emphasis upon the wage and personal characteristics inconventional labor supply analyses of work hours may in part be misplaced.

Approximation Bias in Linearized Euler Equations

A wide range of empirical applications rely on linear approximations to dynamic Euler equations. Among the most notable of these is the large and growing literature on precautionary saving that examines how consumption growth and saving behavior are affected by uncertainty and prudence. Linear approximations to Euler equations imply a linear relationship between expected consumption growth and uncertainty in consumption growth, with a slope coefficient that is a function of the coefficient of relative prudence. This literature has produced puzzling results: Estimates of the coefficient of relative prudence (and the coefficient of relative risk aversion) from regressions of consumption growth on uncertainty in consumption growth imply estimates of prudence and risk aversion that are unrealistically low. Using numerical solutions to a fairly standard intertemporal optimization problem, our results show that the actual relationship between expected consumption growth and uncertainty in consumption growth differs substantially from the relationship implied by a linear approximation. We also present Monte Carlo evidence that shows that the instrumental variables methods commonly used to estimate the parameters correct some, but not all, of the approximation bias.

Exact results for the Barabasi model of human dynamics

Human activity patterns display a bursty dynamics, with interevent times following a heavy tailed distribution. This behavior has been recently shown to be rooted in the fact that humans assign their active tasks different priorities, a process that can be modeled as a priority queueing system [A.-L. Barabasi, Nature 435, 207 (2005)]. In this work we obtain exact results for the Barabasi model with two tasks, calculating the priority and waiting time distribution of active tasks. We demonstrate that the model has a singular behavior in the extremal dynamics limit, when the highest priority task is selected first. We find that independently of the selection protocol, the average waiting time is smaller or equal to the number of active tasks, and discuss the asymptotic behavior of the waiting time distribution. These results have important implications for understanding complex systems with extremal dynamics.Comment: 4 pages, 4 figures, revte

Activation of δ-globin gene expression by erythroid Krupple-like factor: A potential approach for gene therapy of sickle cell disease

Hemoglobin A2 (HbA2; α2δ2) is a powerful inhibitor of HbS (α2β2/(S) polymerization. However, HbA2 levels are normally low in sickle cell patients. We show that a major reason for low δ-globin gene expression is the defective CACCC box at -90 in the δ-globin promoter. When the CACCC box defect in δ is corrected, expression of an HS2 δ/Luciferase reporter is equivalent to HS2 β/Luciferase. Erythroid Krupple-like factor (EKLF), which binds to the CACCC box of the β-globin gene and activates high-level expression, does not bind to the normal δ-globin promoter. Our goal is to design a modified EKLF that binds to the defective δ-globin promoter and enhances δ-globin gene expression. To test the feasibility of this strategy, we inserted the β-globin CACCC box at -90 of the δ-globin gene promoter to produce an HS2 δ(CAC)-β construct and quantitated human δ- and β-globin mRNA in stably transformed murine erythroleukemia (MEL) cells. δ-Globin mRNA in these cells was 22.0% ± 9.0% of total human globin mRNA (δ/δ + β) as compared with 3.0% ± 1.3% in the HS2 δ-β control. In a second set of experiments a GAL4 DNA-binding site was inserted at -90 of the δ-globin gene to produce an HS2 δ(GAL4)-β construct. This construct and a GAL4((1-147))/EKLF expression vector were stably transfected into MEL cells. δ-Globin mRNA in these cells was 27.8% ± 7.1% of total human globin mRNA as compared with 9.9% ± 2.5% in the HS2 δ(GAL4)-β plus GAL4((1-147)) control. These results show that δ-globin gene expression can be significantly increased by a modified EKLF. Based on these results, we suggest that modified EKLFs, which contain zinc fingers designed to bind specifically to the defective δ-globin CACCC box, may be useful in gene therapy approaches to increase HbA2 levels and inhibit HbS polymerization

The Inklings in America

Transcription of a panel discussion at the 19th Mythopoeic Conference

Legal Compliance in Commercial Service Provisioning Across Administrative Domains

Internet design principles do not focus on commercial service provisioning. Hence, support mechanisms need to be implemented in order to ensure that value added services can be offered in a competitive context. Commercial product offerings base on contractual agreements concluded between service providers and service customers. Contracts need to reflect business-driven requirements originating from involved contract parties, while they are invariably required to respect those regulations imposed by commerce law. Legal compliance, thus, determines the available range of applicable contractual terms—irrespective of whether such a contract governs commercial value added services in the Internet or not. Legal determinations are valid in a limited geographical area. The Internet, however, lacks a distinct notion of location. Consequently, technical means to overcome this fundamental design gap are investigated, in order to ensure that legally compliant contracts can be concluded

Distances in random graphs with finite variance degrees

In this paper we study a random graph with $N$ nodes, where node $j$ has degree $D_j$ and $\{D_j\}_{j=1}^N$ are i.i.d. with \prob(D_j\leq x)=F(x). We assume that $1-F(x)\leq c x^{-\tau+1}$ for some $\tau>3$ and some constant $c>0$. This graph model is a variant of the so-called configuration model, and includes heavy tail degrees with finite variance. The minimal number of edges between two arbitrary connected nodes, also known as the graph distance or the hopcount, is investigated when $N\to \infty$. We prove that the graph distance grows like $\log_{\nu}N$, when the base of the logarithm equals \nu=\expec[D_j(D_j -1)]/\expec[D_j]>1. This confirms the heuristic argument of Newman, Strogatz and Watts \cite{NSW00}. In addition, the random fluctuations around this asymptotic mean $\log_{\nu}{N}$ are characterized and shown to be uniformly bounded. In particular, we show convergence in distribution of the centered graph distance along exponentially growing subsequences.Comment: 40 pages, 2 figure