Evidence for a disorder driven phase transition in the condensation of 4He in aerogels

We report on thermodynamic and optical measurements of the condensation process of $^4$He in three silica aerogels of different microstructures. For the two base-catalysed aerogels, the temperature dependence of the shape of adsorption isotherms and of the morphology of the condensation process show evidence of a disorder driven transition, in agreement with recent theoretical predictions. This transition is not observed for a neutral-catalysed aerogel, which we interpret as due to a larger disorder in this case.Comment: 11 page

Report on the Standardization Project ``Formal Methods in Conformance Testing''

This paper presents the latest developments in the “Formal Methods in Conformance Testing” (FMCT) project of ISO and ITU–T. The project has been initiated to study the role of formal description techniques in the conformance testing process. The goal is to develop a standard that defines the meaning of conformance in the context of formal description techniques. We give an account of the current status of FMCT in the standardization process as well as an overview of the technical status of the proposed standard. Moreover, we indicate some of its strong and weak points, and we give some directions for future work on FMCT

A survey of shipping finance research: setting the future research agenda

Financing shipping related investment projects has always been a focal area of debate and research within the international maritime industry since access to funding can determine the competitiveness of a capital-intensive business as well as its success or failure under adverse market conditions. This paper provides, for the first time, a comprehensive and structured survey of all published research in the area of shipping finance and investment. The review spans approximately four decades (1979-2018) of empirical evidence, including 162 studies published in 48 scholarly journals, complemented with select books and book chapters. The study provides a bibliometric analysis and comprehensive synthesis of existing research offering an invaluable source of information for both the academic community and business practice, shaping the future research agenda in shipping finance and investment

Risk and return of private equity: An overview of data, methods, and results

I cover the different methods to measure risk and return of investing into private equity (also called buyout). However, the reader may bear in mind that the challenges and methods are very similar for other assets classes such as venture capital, real estate or mezzanine. In terms of vocabulary, I call a (portfolio) company the entity receiving the financing from a private equity fund, and private equity firm the organization running private equity funds (e.g. KKR funds, Bain capital funds). The capital committed to private equity funds increased from $3.5 billion in 1984 to over$300 billion in 2007 and more than $1 trillion of assets are estimated to be in the hand of private equity funds in 2007. This growth has often been attributed to a widespread belief of stellar performance and low risk but no rate of return has even been shown in support of this belief (only some multiples or IRRs) and no risk measure has been computed. Recent academic evidence which I document below is at odd with this belief. In this chapter, I review studies of risk and return of private equity which I complement with original empirical work. I distinguish between four types of data. Each represents a different level of challenge for measuring risk and return. From the easiest to the most difficult: i) publicly traded vehicles, ii) round valuation data [the econometrician knows the initial and final value of the investment but does not know the time-series of investment values; there is no intermediary cash-flows], iii) investment level [cash flows realized by the fund from an investment], and iv) fund level [cash flows faced by investors for their stake in a fund]. In the last two cases, the econometrician does not have a correspondence between each amount distributed and invested. These two cases require the same method, are most challenging and are the most relevant in practice

Mixed alkali effect in Li and Na aluminophosphate glasses: influence of the cation environment

International audienceThis paper deals with the variation of the mixed alkali effect (MAE) in Li and Na aluminophosphate glasses. The general system investigated is: 0.46 [xNa(2)O(1-x)Li2O], 0.54 [yAl(2)O(3)(1-y)P2O5], with x varying between 0 and 1 to probe the MAE, and y between 0 and 0.08 to modify the cation environment and to try to understand how the amorphous host affects the ionic motions. We show that the do conductivity minimum characteristic of the MAE effect decreases and almost disappears as Al2O3 is added to mixed phosphate glasses. On another hand, the do conductivity of the single alkali glasses is almost not affected by Al2O3 addition. Dielectric relaxation characteristics also change with the Al2O3 concentration in mixed glasses and not in single ones. On another hand, the mixed alkali peak measured using mechanical relaxation appears to be almost not affected by the presence of Al2O3. This decoupling between the mechanical and dielectric relaxation processes appears to "through into question" the proposal that the mechanical relaxation in mixed alkali glasses accounts for sites reconfiguration to adapt to the different cations

Design and realization of an interferometric microimaging system working in the EUV range

A dedicated interferometric microimaging system has been designed and build to produce a magnified, diffraction limited image-interferogram of a coherently illuminated object, e.g. a laser plasma illuminated by a soft X-ray laser. The optical system consists of quasi-ellipsoïdal, multilayered mirror, illuminated at a 6 deg incidence from normal, associated with a grazing incidence Fresnel-bimirror interferometer. The working distance (optics to object) is [MATH]. The corrected aperture is 8x8 mm square. The magnification can be 10 or more, without loss of resolution. In a first realization, the ellipsoïdal mirror shape was approximated by a quasi-ideal torus, making the system not diffraction limited. The expected resolution (3-4 µm) was checked by imaging a metallic grid at 21.2 nm. In a second step, we have produced a better approximation of the ellipsoïd, which is diffraction limited at [MATH], under incidence 6.08 deg from normal. In this case, the actual corrected field is at least 0.9 mm, and the interferometric field is 0.6 mm perpendicular to fringes (these distances on object side). We discuss the design principles, leading to the choice of the various optical parameters, and the realization techniques