Highly Indistinguishable Single Photons from Droplet-Etched GaAs Quantum Dots Integrated in Single-Mode Waveguides and Beamsplitters.

Integration of on-demand quantum emitters into photonic integrated circuits (PICs) has drawn much attention in recent years, as it promises a scalable implementation of quantum information schemes. A central property for several applications is the indistinguishability of the emitted photons. In this regard, GaAs quantum dots (QDs) obtained by droplet etching epitaxy show excellent performances, making the realization of these QDs into PICs highly appealing. Here, we show the first implementation in this direction, realizing the key passive elements needed in PICs, i.e., single-mode waveguides (WGs) with integrated GaAs-QDs and beamsplitters. We study the statistical distribution of wavelength, linewidth, and decay time of the excitonic line, as well as the quantum optical properties of individual emitters under resonant excitation. We achieve single-photon purities as high as 1 - g(2)(0) = 0.929 ± 0.009 and two-photon interference visibilities of up to VTPI = 0.953 ± 0.032 for consecutively emitted photons.

From Malthusian Disequilibrium to the Post-Malthusian Era: The Evolution of the Preventive and Positive Checks in Germany, 1730-1870.

This study draws on a new data set of vital rates and real wages to explore short-term and long-term behavior of the preventive and positive checks in a major economy of premodern mainland Europe. Four results stand out. First, the preventive check was fairly stable throughout the period 1730-1870; its magnitude of 0.2 to 0.35 was comparable with that of England, northern and central Italy, and Sweden. Second, the eighteenth century was characterized by Malthusian disequilibrium in that there was no long-term relationship between the crude death rate and the real wage, whereas the crude death rate's instantaneous response to income changes was a substantial -0.4. Third, the short-term positive check may have weakened over the eighteenth century and largely disappeared in the 1810s. The diversification of food risk resulting from the spread of potato cultivation, market integration, and the development of the nonagricultural sectors are potential explanations of the demise and disappearance of the positive check. Fourth, between the 1810s and the 1860s, vital rates and the real wage were stationary, which is consistent with a post-Malthusian regime in which technological progress depended on population size. The 1810s marked the time when Germany transited from a Malthusian regime in disequilibrium to the post-Malthusian era.

Bone debris: dead matter or vital osteoblasts.

BACKGROUND: Mechanical manipulation, pressure, and temperature increase can induce bone necrosis during intramedullary reaming. METHODS: In this study, the bone debris obtained after reaming 18 sheep tibiae was analyzed to investigate its vitality by measuring alkaline phosphatase activity. Two different reamer designs were used for the project. Bone cells were first cultivated in a specific growth medium, counted 3 weeks after the reaming procedure, and then cultivated for another 5 weeks. RESULTS: At the end of the project, qualitative evaluation showed positive alkaline phosphatase activity in most of the cases, and quantitative evaluation also showed enzyme activity. The positive alkaline phosphatase results were independent of the reamer sizes and reamer design. No significant results were obtained from a comparison of different reamer sizes and designs. This indicates that osteoblasts survive after correctly performed reaming. CONCLUSION: The results prove the vitality of the bone debris and confirm clinical observations.