Entrepreneurial Innovation and Sustained Long-run Growth without Weak or Strong Scale Effects

R&D-based growth theory suggests that a larger population size raises either the long-run rate of economic growth (“strong scale effect”) or the level of per capita income (“weak scale effect”), with far-reaching policy implications. However, for modern times there is little empirical support for strong scale effects and evidence in favor of weak scale effects is mixed, at best. This paper develops a simple overlapping-generations framework with endogenous occupational choice of heterogeneous agents and entrepreneurial innovations in which any form of scale effect is absent. A higher population growth rate has a negligible, possibly negative effect on the long-run growth rate of per capita income. Long-run growth is sustained also in absence of population growth and generally is policy-dependent.economic growth, endogenous technical change, entrepreneurial skills, population growth, scale effects

How to Promote R&D-based Growth? Public Education Expenditure on Scientists and Engineers versus R&D Subsidies

Empirical evidence suggests that positive externalities from R&D exceed negative ones. According to conventional wisdom, this calls for R&D subsidies. This paper develops a quality-ladder growth model with overlapping generations which evaluates the positive and normative implications of R&D subsidies and compares them with the effects of public education policy to promote R&D. Unlike standard growth models, the proposed framework accounts for the specificity of science and engineering (S&E) skills, where individuals endogenously choose the type of education, and allows for heterogeneity in individual ability. Although intertemporal knowledge spillovers are hypothesized and negative R&D externalities are absent, the analysis shows somewhat surprisingly that R&D subsidies may be detrimental to both productivity growth and welfare, in contrast to publicly provided education targeted to S&E skills. Finally, the optimal structure of public education spending on different skills is examined.education policy, endogenous growth, R&D subsidies, scientists and engineers, skill specificity

Risky Human Capital Investment, Income Distribution, and Macroeconomic Dynamics

This paper demonstrates that the role of the personal income distribution for an economy's process of development through risky human capital accumulation critically depends on the shape of the saving function. Empirical evidence for the U.S. strongly suggests that the marginal propensity to save is increasing in income, a property which so far has not been allowed for in the literature on human capital, income distribution and macroeconomics. Doing so, the present analysis suggests that the impact of higher inequality on the aggregate human capital stock, and thus, on growth is positive under rather weak conditions. Results heavily rely on a positive impact of parents. income on children's human capital investments, which holds under standard assumptions on labor income risk and risk aversion in the model, and is largely supported by empirical evidence.Growth, Income Distribution, Intergenerational Transfers, Risky Education, Saving Function.

Income Inequality, Voting Over the Size of Public Consumption, and Growth

According to a standard argument, higher income inequality fosters redistributive activities of the government in favor of the median income earner. This paper shows that if redistribution is achieved by a public provision of goods and services rather than by transfers, higher income inequality may imply a smaller size of the government in majority voting equilibrium. In addition to a static voting model, an endogenous growth model is analyzed to examine the role of saving decisions of heterogeneous individuals for both the distributional incidence of proportional factor income taxes and the voting outcome.income distribution, public consumption, majority voting, investment-driven growth

Optimization of electron pumping by harmonic mixing

For a symmetric bridge coupled to infinite leads, in the presence of a dipole-coupled external ac-field with harmonic mixing, we solve the Schr\"odinger equation in the time-domain using open boundary conditions as well as in the energy-domain using Floquet scattering theory. As this potential breaks parity and generalized parity, we find a non-vanishing average current. We then optimize the relative amplitude ratio between the fundamental and the second harmonic leading to a maximum in the pump current.Comment: 13 pages, 6 figures, accepted at Phys. Rev. B, http://prb.aps.org/accepted/B/7b073O7dMc412f17647d3877ee3ac5c3e271dcb1

Scaling in thermal convection: A unifying theory

A systematic theory for the scaling of the Nusselt number $Nu$ and of the Reynolds number $Re$ in strong Rayleigh-Benard convection is suggested and shown to be compatible with recent experiments. It assumes a coherent large scale convection roll (``wind of turbulence'') and is based on the dynamical equations both in the bulk and in the boundary layers. Several regimes are identified in the Rayleigh number versus Prandtl number phase space, defined by whether the boundary layer or the bulk dominates the global kinetic and thermal dissipation, respectively. The crossover between the regimes is calculated. In the regime which has most frequently been studied in experiment (Ra smaller than 10^{11}) the leading terms are $Nu\sim Ra^{1/4}Pr^{1/8}$, $Re \sim Ra^{1/2} Pr^{-3/4}$ for $Pr < 1$ and $Nu\sim Ra^{1/4}Pr^{-1/12}$, $Re \sim Ra^{1/2} Pr^{-5/6}$ for $Pr > 1$. In most measurements these laws are modified by additive corrections from the neighboring regimes so that the impression of a slightly larger (effective) Nu vs Ra scaling exponent can arise. -- The presented theory is best summarized in the phase diagram figure 1.Comment: 30 pages, latex, 7 figures, under review at Journal of Fluid Mec

Contest for Attention in a Quality-Ladder Model of Endogenous Growth

This paper develops a quality-ladder model of endogenous growth to study the interplay between in-house R&D and marketing expenditure. Although promotional activity is modelled as purely wasteful competition among firms for attention, it unambiguously fosters innovation activity of firms, and possibly, leads to faster growth. This result rests on two premises which are consistent with empirical evidence. First, if firms incur higher sunk costs for marketing, concentration and firm sizes rise. Second, firm size and R&D expenditure are positively related. As a result, R&D investments per firm may even become excessive, whereas being inefficiently low in the benchmark case without marketing. This has non-trivial consequences for the socially optimal policy design with respect to R&D subsidies and entry incentives.contest for attention, endogenous growth, innovation activity, marketing, R&D subsidies, scale effects

Spectra of Harmonium in a magnetic field using an initial value representation of the semiclassical propagator

For two Coulombically interacting electrons in a quantum dot with harmonic confinement and a constant magnetic field, we show that time-dependent semiclassical calculations using the Herman-Kluk initial value representation of the propagator lead to eigenvalues of the same accuracy as WKB calculations with Langer correction. The latter are restricted to integrable systems, however, whereas the time-dependent initial value approach allows for applications to high-dimensional, possibly chaotic dynamics and is extendable to arbitrary shapes of the potential.Comment: 11 pages, 1 figur