Winds of Change: Short Stories About Our Climate edited by Mary Woodbury

Review of Mary Woodbury\u27s edited collection, Winds of Change: Short Stories about Our Climate

There is a VaR beyond usual approximations

Basel II and Solvency 2 both use the Value-at-Risk (VaR) as the risk measure to compute the Capital Requirements. In practice, to calibrate the VaR, a normal approximation is often chosen for the unknown distribution of the yearly log returns of financial assets. This is usually justified by the use of the Central Limit Theorem (CLT), when assuming aggregation of independent and identically distributed (iid) observations in the portfolio model. Such a choice of modeling, in particular using light tail distributions, has proven during the crisis of 2008/2009 to be an inadequate approximation when dealing with the presence of extreme returns; as a consequence, it leads to a gross underestimation of the risks. The main objective of our study is to obtain the most accurate evaluations of the aggregated risks distribution and risk measures when working on financial or insurance data under the presence of heavy tail and to provide practical solutions for accurately estimating high quantiles of aggregated risks. We explore a new method, called Normex, to handle this problem numerically as well as theoretically, based on properties of upper order statistics. Normex provides accurate results, only weakly dependent upon the sample size and the tail index. We compare it with existing methods.Comment: 33 pages, 5 figure

Measurements of r-process nuclei

Progress in the astrophysical understanding of r-process nucleosynthesis also depends on the knowledge of nuclear-physics quantities of extremely neutron-rich isotopes. In this context, experiments at CERN-ISOLDE have played a pioneering role in exploring new shell-structure far from stability. Possible implications of new nuclear-data input on the reproduction of r-abundance observations are presented.Comment: 10 pages, 3 figures; Proc. "Nuclei in the Cosmos 2000", Nucl. Phys.

Level crossings and other level functionals of stationary Gaussian processes

This paper presents a synthesis on the mathematical work done on level crossings of stationary Gaussian processes, with some extensions. The main results [(factorial) moments, representation into the Wiener Chaos, asymptotic results, rate of convergence, local time and number of crossings] are described, as well as the different approaches [normal comparison method, Rice method, Stein-Chen method, a general $m$-dependent method] used to obtain them; these methods are also very useful in the general context of Gaussian fields. Finally some extensions [time occupation functionals, number of maxima in an interval, process indexed by a bidimensional set] are proposed, illustrating the generality of the methods. A large inventory of papers and books on the subject ends the survey.Comment: Published at http://dx.doi.org/10.1214/154957806000000087 in the Probability Surveys (http://www.i-journals.org/ps/) by the Institute of Mathematical Statistics (http://www.imstat.org

Is spatial mobility a reproduction mechanism of inequality? An empirical analysis of the job search behavior and the international mobility of students and re-cent graduates

Concentrating on the social origin, determinants of international mobility of students and recent graduates are identified, drawing on a combination of the microeconomic human capital model as well as the job-search-theory. The analysis is based on the Bavarian Graduate Study (Bayerisches Absolventen Panel, BAP), a representative data base for a wide array of fields of study at Bavarian universities and universities of applied sciences. Methods of multilevel modeling are employed to identify individual differences in the spatial mobility propensities of students and young graduates. First, analyzing the determinants of international mobility of students revealed the following associations. The younger the students, the higher the likelihood to study abroad. This propensity is also positively associated with parents’ status. Apart from that, students from universities display a significantly higher migration propensity than students from universities of applied sciences. Second, considering differences in the emigration propensities after graduation, our results imply that the likelihood of working abroad is contingent on a high social origin, being a single, graduating at a lower age. Furthermore, migration experiences in the past and competencies in foreign languages show a positive impact. Consequently, international mobility both during the studies and upon entrance into the labor market is significantly influenced by the social origin. In addition to this direct effect, the higher likelihood of students and graduates with a favorable social background to experience mobility in early stages increases their propensity to go abroad again indirectly, too, as a mediator. The same holds true for the readiness to move for a job as indicated by the radius considered when searching for a job. As a result, the range of opportunities resulting from the combined effects of a high social origin and previous migration experiences resembles a sophisticated mechanism contributing to the reproduction of social inequality.international mobility, students, graduates, social origin, inequality, job search