An Empirical Model of Growth Through Product Innovation

Productivity dispersion across firms is large and persistent, and worker reallocation among firms is an important source of productivity growth. The purpose of the paper is to estimate the structure of an equilibrium model of growth through innovation that explains these facts. The model is a modified version of the Schumpeterian theory of firm evolution and growth developed by Klette and Kortum (2004). The data set is a panel of Danish firms than includes information on value added, employment, and wages. The model's fit is good and the structural parameter estimates have interesting implications for the aggregate growth rate and the contribution of worker reallocation to it.labor productivity growth; worker reallocation; firm dynamics; firm panel data estimation

Productivity Growth and Worker Reallocation: Theory and Evidence

Dispersion in labor and factor productivity across firms is large and persistent, large flows of workers move across firms, and worker reallocation is an important source of productivity growth. The purpose of the paper is to provide a formal explanation for these observations that clarifies the role of worker reallocation as a source of productivity growth. Specifically, we study a modified version of the Schumpeterian model of growth induced by product innovation developed by Klette and Kortum (2002). More productive firms are those that supply higher quality products in the model. We show that more productive firms grow faster and the reallocation of workers across continuing firms contributes to aggregate productivity growth if and only if current productivity predicts future productivity. We provide evidence in support of the hypothesis that more productive firms become larger in Danish data. In addition, we provide estimates of the distribution of productivity at entry and the parameters of the cost of investment in innovation function and other structural parameters that all firms are assumed to face by fitting the model to observations on value added, employment, and wages drawn from a panel of Danish firms for the years 1992-1997.

On the Job Search and the Wage Distribution

Estimates of the structural parameters of a job separation model derived from the theory of on-the-job search are reported in this paper. Given that each employer pays the same wage to observably equivalent workers but wages are dispersed across employers, the theory implies that an employer's separation flow is the sum of an exogenous outflow unrelated to the wage paid and a job-to-job flow that decreases with the employer's wage. The specification estimated allows worker search effort to depend on the wage currently earned. The empirical results imply that search effort declines with the wage paid, as the theory predicts, using Danish IDA data for the years 1994-1995. Furthermore, the estimates for the full sample and four occupational sub-samples explain the employment effect, defined as the horizontal difference between the distribution of wages earned and the distribution of wages offered.

Reconstruction of the biosynthetic pathway for the core fungal polyketide scaffold rubrofusarin in Saccharomyces cerevisiae

BACKGROUND: Fungal polyketides include commercially important pharmaceuticals and food additives, e.g. the cholesterol-lowering statins and the red and orange monascus pigments. Presently, production relies on isolation of the compounds from the natural producers, and systems for heterologous production in easily fermentable and genetically engineerable organisms, such as Saccharomyces cerevisiae and Escherichia coli are desirable. Rubrofusarin is an orange polyketide pigment that is a common intermediate in many different fungal biosynthetic pathways. RESULTS: In this study, we established a biosynthetic pathway for rubrofusarin in S. cerevisiae. First, the Fusarium graminearum gene encoding polyketide synthase 12 (PKS12) was heterologously co-expressed with the Aspergillus fumigatus gene encoding phosphopantetheinyl transferase (npgA) resulting in production of YWA1. This aromatic heptaketide intermediate was converted into nor-rubrofusarin upon expression of the dehydratase gene aurZ from the aurofusarin gene cluster of F. graminearum. Final conversion into rubrofusarin was achieved by expression of the O-methyltransferase encoding gene aurJ, also obtained from the aurofusarin gene cluster, resulting in a titer of 1.1 mg/L. Reduced levels of rubrofusarin were detected when expressing PKS12, npgA, and aurJ alone, presumably due to spontaneous conversion of YWA1 to nor-rubrofusarin. However, the co-expression of aurZ resulted in an approx. six-fold increase in rubrofusarin production. CONCLUSIONS: The reconstructed pathway for rubrofusarin in S. cerevisiae allows the production of a core scaffold molecule with a branch-point role in several fungal polyketide pathways, thus paving the way for production of further natural pigments and bioactive molecules. Furthermore, the reconstruction verifies the suggested pathway, and as such, it is the first example of utilizing a synthetic biological “bottom up” approach for the validation of a complex fungal polyketide pathway

An association of adult personality with prenatal and early postnatal growth: the EPQ lie-scale

BACKGROUND: Recent studies have noted differences in social acquiescence and interpersonal relations among adults born preterm or with very low birth weight compared to full term adults. In addition, birth weight has been observed to be negatively correlated with lie-scale scores in two studies. We attempted to replicate and extend these studies by examining young adult lie-scale scores in a Danish birth cohort. METHOD: Weight, length and head circumference of 9125 children from the Copenhagen Perinatal Cohort were measured at birth and at 1, 3 and 6 years. A subsample comprising 1182 individuals participated in a follow-up at 20–34 years and was administered the Eysenck Personality Questionnaire (EPQ) which includes a lie-scale (indicating social acquiescence or self-insight). Associations between lie-scale scores and weight, length and head circumference respectively were analysed by multiple linear regression adjusting for single-mother status, parity, mother’s age, father’s age, parental social status, age at EPQ measurement, intelligence, and adult size. RESULTS: Male infants with lower weight, length, and head-circumference at birth and the following three years grew up to have higher scores on the lie-scale as young adults. Most of these associations remained significant after adjustment for the included covariates. No associations were found for females. Analyses were also conducted with neuroticism, extraversion and psychoticism as outcome variables, but no significant associations were found for these traits after adjustment. CONCLUSIONS: The findings replicate and extend findings from previous studies suggesting that size at birth and during the first three years of life is significantly associated with social acquiescence in adult men. They highlight the potential influence of prenatal and early postnatal development on personality growth and development