Essays on the labor force participation of older men

This work is composed of two self-contained chapters that examine the Labor Force Participation (LFP) behavior of older men in the United States. The first chapter analyzes the effect of wealth on LFP. I use an Instrumental Variables (IV) estimation approach that corrects for measurement error in wealth and unobservable taste variation across individuals. Previous studies that do not control for these factors have found that wealth has very little effect on retirement. My IV results reveal a larger wealth effect than in most previous studies; a $20k increase in wealth reduces the probability of LFP by about 1 percentage point. The instruments are local housing price growth and unanticipated inheritances. I cannot reject the hypothesis that the effects of housing and non-housing wealth on LFP are equal, although the power of my test is low. Thus, my analysis suggests that older men are equally willing to “spend” an increase in housing and non-housing wealth on earlier retirement. In the second chapter, my co-author (David Blau) and I examine trends in the Labor Force Participation Rate (LFPR) of older men. After nearly a full century of decline, the LFPR of older men in the United States leveled off in the 1980s, and began to increase in the late 1990s. We use a time series of cross sections from 1962 to 2005 to model the LFPR of men aged 55-69, with the aim of determining whether changes in the rules governing Social Security benefits can explain these trends. Our results indicate that the decline in the LFPR from the 1960s through the 1980s cannot be explained by the increasing generosity of Social Security during this period. The recent increase in the LFPR of older men can be explained by changes in the composition of the older male population away from high school dropouts and toward college attendees and graduates. Changes in Social Security may have contributed to the recent increase as well, but this result is sensitive to specification

Putative DHHC-Cysteine-Rich Domain S-Acyltransferase in Plants

Protein S-acyltransferases (PATs) containing Asp-His-His-Cys within a Cys-rich domain (DHHC-CRD) are polytopic transmembrane proteins that are found in eukaryotic cells and mediate the S-acylation of target proteins. S-acylation is an important secondary and reversible modification that regulates the membrane association, trafficking and function of target proteins. However, little is known about the characteristics of PATs in plants. Here, we identified 804 PATs from 31 species with complete genomes. The analysis of the phylogenetic relationships suggested that all of the PATs fell into 8 groups. In addition, we analysed the phylogeny, genomic organization, chromosome localisation and expression pattern of PATs in Arabidopsis, Oryza sative, Zea mays and Glycine max. The microarray data revealed that PATs genes were expressed in different tissues and during different life stages. The preferential expression of the ZmPATs in specific tissues and the response of Zea mays to treatments with phytohormones and abiotic stress demonstrated that the PATs play roles in plant growth and development as well as in stress responses. Our data provide a useful reference for the identification and functional analysis of the members of this protein family

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Can Social Security Explain Trends in Labor Force Participation of Older Men in the United States?

After a long decline, the Labor Force Participation Rate (LFPR) of older men in the United States leveled off in the 1980s, and began to increase in the late 1990s. We examine how changes in Social Security rules affected these trends. We attribute only a small portion of the decline from the 1960s–80s to the increasing generosity of Social Security over this period. Increases in the Full Retirement Age and the Delayed Retirement Credit explain one quarter to one half of the recent increase in the LFPR. Increasing educational attainment and increasing LFPR of married women also contributed to the recent rise.