Entrepreneurial exit in real and imagined markets

Entrepreneurs exit their business due to selection pressures experienced in the market place, i.e. business failure. Next to this well known ex-post decision to exit, entrepreneurs select exantewhether they are willing to pursue an entrepreneurial career at all, or to give up theseentrepreneurial intentions. Hardly anything is known about the latter selection process in imagined markets that precedes the variety creation and selection process in real markets. This paper explores and explains the prevalence of these two selection processes using survey data on 20,000 individuals in 27 European countries and the US in 2007. We distinguish business failures from exit by sell-off. Results indicate that individuals in the US are less likely to exit imagined markets, and are more likely to have exited the real market (especially by selling their business) than Europeans. Individuals in a Corporatist welfare state regime have relatively high chances to exit imagined markets. Business owners in urban environments are more likely to fail, while individuals with a high risk tolerance, a high education and self-employed parents are less likely to exit in imagined as well as in real markets (via business failure). This study shows that exit in real and in imagined markets is differently affected by competition and institutions. These selection environments have differential effects on entrepreneurial aspirations and actions of individuals, and provide evidence for the dissimilar nature of exit in real and exit in imagined markets.

Ambitious entrepreneurship, high-growth firms and macroeconomic growth

We examine the impact of ambitious entrepreneurship (entrepreneurs expecting to grow their firm) and high-growth firms (firms that have actually realized high growth rates) on subsequent macroeconomic growth in a sample of high and low-income countries, in the period 2002-2005. Our empirical evidence shows that once we control for the share of ambitious entrepreneurs the overall positive effect of entrepreneurship on macroeconomic growth disappears. Growthoriented entrepreneurship seems to contribute heavily to macroeconomic growth in both low- and high-income countries. In low-income countries, the overall positive effect of entrepreneurship on macroeconomic growth does not disappear after introducing the share of ambitious entrepreneurs into the statistical model. In contrast to ambitious entrepreneurship in nascent and young businesses, established high-growth firms do not seem to contribute to macroeconomic growth.These established high-growth firms seem to flourish in countries with high levels of entrepreneurship in general, while there appears to be no connection between the rate of high-growth firms and the share of ambitious entrepreneurs. �

Efficacy of tofacitinib monotherapy in methotrexate-naive patients with early or established rheumatoid arthritis.

IntroductionTofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). Tofacitinib monotherapy was previously shown to inhibit structural damage, reduce clinical signs and symptoms of RA, and improve physical functioning over 24 months in methotrexate (MTX)-naive adult patients with RA. In this post hoc analysis, we compared efficacy and safety of tofacitinib in patients with early (disease duration <1 year) versus established (≥1 year) RA.MethodsMTX-naive patients ≥18 years with active RA received tofacitinib monotherapy (5 or 10 mg two times a day, or MTX monotherapy, in a 24-month Phase 3 trial.ResultsOf 956 patients (tofacitinib 5 mg two times a day, n=373; tofacitinib 10 mg two times a day, n=397; MTX, n=186), 54% had early RA. Baseline disease activity and functional disability were similar in both groups; radiographic damage was greater in patients with established RA. At month 24, clinical response rates were significantly greater in patients with early versus established RA in the tofacitinib 5 mg two times a day group. Both tofacitinib doses had greater effects on clinical, functional and radiographic improvements at 1 and 2 years compared with MTX, independent of disease duration. No new safety signals were observed.ConclusionsTreatment response was generally similar in early and established RA; significantly greater improvements were observed at month 24 with tofacitinib 5 mg two times a day in early versus established RA. Tofacitinib 5 and 10 mg two times a day demonstrated greater efficacy versus MTX irrespective of disease duration. No difference in safety profiles was observed between patients with early or established RA.Trial registration numberNCT01039688; Results

Highly efficient room temperature spin injection in a metal-insulator-semiconductor light emitting diode

We demonstrate highly efficient spin injection at low and room temperature in an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOx tunnel spin injector. We use a double-step oxide deposition for the fabrication of a pinhole-free AlOx tunnel barrier. The measurements of the circular polarization of the electroluminescence in the Oblique Hanle Effect geometry reveal injected spin polarizations of at least 24% at 80K and 12% at room temperature

Quantitative Study of Magnetotransport through a (Ga,Mn)As Single Ferromagnetic Domain

We have performed a systematic investigation of the longitudinal and transverse magnetoresistance of a single ferromagnetic domain in (Ga,Mn)As. We find that, by taking into account the intrinsic dependence of the resistivity on the magnetic induction, an excellent agreement between experimental results and theoretical expectations is obtained. Our findings provide a detailed and fully quantitative validation of the theoretical description of magnetotransport through a single ferromagnetic domain. Our analysis furthermore indicates the relevance of magneto-impurity scattering as a mechanism for magnetoresistance in (Ga,Mn)As.Comment: 5 pages, 4 figures; v2: missing references included, figures recompressed to improve readabilit

Integrability of irrotational silent cosmological models

We revisit the issue of integrability conditions for the irrotational silent cosmological models. We formulate the problem both in 1+3 covariant and 1+3 orthonormal frame notation, and show there exists a series of constraint equations that need to be satisfied. These conditions hold identically for FLRW-linearised silent models, but not in the general exact non-linear case. Thus there is a linearisation instability, and it is highly unlikely that there is a large class of silent models. We conjecture that there are no spatially inhomogeneous solutions with Weyl curvature of Petrov type I, and indicate further issues that await clarification.Comment: Minor corrections and improvements; 1 new reference; to appear Class. Quantum Grav.; 16 pages Ioplpp

Electrical Spin Injection in a Ferromagnetic / Tunnel Barrier/ Semiconductor Heterostructure

We demonstrate experimentally the electrical ballistic electron spin injection from a ferromagnetic metal / tunnel barrier contact into a semiconductor III-V heterostructure. We introduce the Oblique Hanle Effect technique for reliable optical measurement of the degree of injected spin polarization. In a CoFe / Al2O3 / GaAs / (Al,Ga)As heterostructure we observed injected spin polarization in excess of 8 % at 80K.Comment: 5 pages, 4 figure

Polarization tomography of metallic nanohole arrays

We report polarization tomography experiments on metallic nanohole arrays with square and hexagonal symmetry. As a main result, we find that a fully polarized input beam is partly depolarized after transmission through a nanohole array. This loss of polarization coherence is found to be anisotropic, i.e. it depends on the polarization state of the input beam. The depolarization is ascribed to a combination of two factors: i) the nonlocal response of the array due to surface plasmon propagation, ii) the non-plane wave nature of a practical input beam.Comment: 4 pages, 3 figures, 1 table, submitted to PR