Necessity and Opportunity Entrepreneurs and their Duration in Self-employment: Evidence from German Micro Data

Using data from the German Socio-Economic Panel Study (GSOEP), we analyze whether necessity entrepreneurs differ from opportunity entrepreneurs in terms of self-employment duration. Using univariate statistics, we find that opportunity entrepreneurs remain in self-employment longer than necessity entrepreneurs. However, after controlling for the entrepreneurs’ education in the professional area where they start their venture, this effect is no longer significant. We therefore conclude that the difference observed is not an original effect but rather is due to selection. We then go on to discuss the implications of our findings for entrepreneurship-policy making, and give suggestions to improve governmental start-up programs

Financial systems, innovation and economic performance

There is growing evidence of international divergence in the performance of newindustries. While the United States is at the forefront of the recent revolution ininformation technologies, European economists and policy makers are concerned thatEurope is falling behind with negative implications for long-term economicperformance. This paper investigates the role of financial systems as a crucialdeterminant of apparent differences in national abilities to promote innovativeactivities in specific sectors. Firstly, a short overview of the relevant finance andinnovation literature is provided, and a synthetic view of the finance-innovation linkis sketched. It is argued that national financial systems have an impact on thestructure of growth through their differing abilities to promote innovation in sector-specifictechnology regimes. Secondly, I apply a simple econometric model to a dataset consisting of 17 OECD countries and 20 manufacturing industries to identifyempirical patterns. The evidence suggests that sectors characterized by hightechnological opportunity and a focus on product innovation perform relatively betterin financial systems with large stock markets, competitive banking sectors and goodaccounting standards. In contrast, the performance of sectors geared towardsinnovation in processes benefits from a more bank-oriented financial system andconcentrated ownership structures.economics of technology ;

Measurements of farfield sound generation from a flow-excited cavity

Results of 1/3-octave-band spectral measurements of internal pressures and the external acoustic field of a tangentially blown rectangular cavity are compared. Proposed mechanisms for sound generation are reviewed, and spectra and directivity plots of cavity noise are presented. Directivity plots show a slightly modified monopole pattern. Frequencies of cavity response are calculated using existing predictions and are compared with those obtained experimentally. The effect of modifying the upstream boundary layer on the noise was investigated, and its effectiveness was found to be a function of cavity geometry and flow velocity

Experimental investigation of reactor-loop transients during startup of a simulated SNAP-8 system

Primary loop transients during startup of Rankine cycle space power system in SNAP 8 simulato

Experimental pressure drop investigation of wetting and nonwetting mercury condensing in uniformly tapered tubes

Pressure drop of wetting and nonwetting mercury condensing in tapered tubes - turbogenerator system

Ground state of a confined Yukawa plasma

The ground state of an externally confined one-component Yukawa plasma is derived analytically. In particular, the radial density profile is computed. The results agree very well with computer simulations on three-dimensional spherical Coulomb crystals. We conclude in presenting an exact equation for the density distribution for a confinement potential of arbitrary geometry.Comment: 5 pages, 4 figure

Revisiting African Agriculture: Institutional Change and Productivity Growth

Africa is largely agrarian, and the performance of agriculture shapes the performance of its economies. It has long been argued that economic development in Africa is strongly conditioned by politics. Recent changes in Africa’s political systems enables us to test this argument and, by extension, broader claims about the impact of political institutions on economic development. Building on a recent analysis of total factor productivity growth in African agriculture, we find that the introduction of competitive presidential elections in the last decades of the twentieth century appears to have altered political incentives, resulting in policy reforms that have enhanced the performance of farmers.African and African American StudiesGovernmen

Self-Consistent Response of a Galactic Disk to an Elliptical Perturbation Halo Potential

We calculate the self-consistent response of an axisymmetric galactic disk perturbed by an elliptical halo potential of harmonic number m = 2, and obtain the net disk ellipticity. Such a potential is commonly expected to arise due to a galactic tidal encounter and also during the galaxy formation process. The self-gravitational potential corresponding to the self-consistent, non-axisymmetric density response of the disk is obtained by inversion of Poisson equation for a thin disk. This response potential is shown to oppose the perturbation potential, because physically the disk self-gravity resists the imposed potential. This results in a reduction in the net ellipticity of the perturbation halo potential in the disk plane. The reduction factor denoting this decrease is independent of the strength of the perturbation potential, and has a typical minimum value of 0.75 - 0.9 for a wide range of galaxy parameters. The reduction is negligible at all radii for higher harmonics (m > or = 3) of the halo potential. (abridged).Comment: 26 pages (LaTex- aastex style), 3 .eps figures. To appear in the Astrophysical Journal, Vol. 542, Oct. 20, 200