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

Very Luminous Carbon Stars in the Outer Disk of the Triangulum Spiral Galaxy

Stars with masses in the range from about 1.3 to 3.5 Mo pass through an evolutionary stage where they become carbon stars. In this stage, which lasts a few Myr, these stars are extremely luminous pulsating giants. They are so luminous in the near-infrared that just a few of them can double the integrated luminosity of intermediate-age (0.6 to 2 Gyr) Magellanic Cloud clusters at 2.2 microns. Astronomers routinely use such near-infrared observations to minimize the effects of dust extinction, but it is precisely in this band that carbon stars can contribute hugely. The actual contribution of carbon stars to the outer disk light of evolving spiral galaxies has not previously been morphologically investigated. Here we report new and very deep near-IR images of the Triangulum spiral galaxy M33=NGC 598, delineating spectacular arcs of carbon stars in its outer regions. It is these arcs which dominate the near-infrared m=2 Fourier spectra of M33. We present near-infrared photometry with the Hale 5-m reflector, and propose that the arcs are the signature of accretion of low metallicity gas in the outer disk of M33.Comment: 4 pages, 4 figures. Revised version submitted to A&A Letter