Business performance and angels presence: A fresh look from France 2008–2011

Business angels enjoy a strong reputation for being more efficient than other investors among policy makers, practitioners, and scholars. However, due to the limited availability of specific financial data, previous research has barely assessed the impact of angels on companies’ performance. This paper seeks to bridge this gap by providing evidence from a unique dataset made up of 432 angel-backed French companies which are compared to two control groups, one randomly selected and another one consisting of similar enterprises. This double comparison process enables us to purge our analysis of structural effect and to demonstrate the importance of the methodology in generating the sample. Indeed, the results we obtain significantly differ depending on the control group. Our results show that the positive influence of angels depends on the condition of the comparison. The set of BA-backed companies is more likely to exhibit superior performance when it is compared to a random sample whereas the companies’ performance is either identical or worse when it is compared to a sample composed of k-nearest neighbors. In addition, using a quantile regression technique makes it possible to differentiate the effect of business angels based on the distribution of the value of the growth rate. © 2017, Springer Science+Business Media New York

Leaching of rock-concrete interfaces

It has been shown that contacts between host rock and engineered barriers may be critical in the design of deep radioactive waste repositories. Water is expected to reach the interface zone after the resaturation of the geological massive and its presence may lead to concrete leaching. Such a phenomenon could increase the interface transmissivity and compromise the confinement of radioactive waste. This paper intends to investigate the influence of concrete leaching on the hydromechanical behaviour of host rock-concrete interfaces. Some concrete specimens have been subjected to an accelerated leaching process using ammonium nitrate. The hydromechanical response of degraded concrete-rock interfaces has been studied under shearing and compared to that of sound interfaces. Consistent with the results available in the literature on bulk concrete, a loss of mechanical strength has been observed for the degraded interface. Unlike the sound specimens, the degraded interfaces do not dilate when sheared and they tend to be closed, thereby preventing water from flowing