Ab initio many-body calculations of static dipole polarizabilities of linear carbon chains and chain-like boron clusters

In this paper we report a theoretical study of the static dipole polarizability of two one-dimensional structures: (a) linear carbon chains C$_{n} (n=2-10)$ and (b) ladder-like planar boron chains B$_{n} (n=4-14)$. The polarizabilities of these chains are calculated both at the Hartree-Fock and the correlated level by applying accurate ab initio quantum chemical methods. Methods such as restricted Hartree-Fock, multi-configuration self-consistent field, multi-reference configuration-interaction method, M{\o}ller-Plesset second-order perturbation theory, and coupled-cluster singles, doubles and triples level of theory were employed. Results obtained from ab initio wave-function-based methods are compared with the ones obtained from the density-functional theory. For the clusters studied, directionally averaged polarizability per atom for both the systems is seen to increase with the chain size.Comment: 9 pages, 3 figures (included

Theory of second harmonic generation in few-layered MoS2

Recent experimental results have demonstrated the ability of monolayer MoS$_2$ to efficiently generate second harmonic fields with susceptibilities between 0.1 and 100 nm/V. However, no theoretical calculations exist with which to interpret these findings. In particular, it is of interest to theoretically estimate the modulus of the second harmonic response, since experimental reports on this differ by almost three orders of magnitude. Here, we present single-particle calculations of the second harmonic response based on a tight-binding band structure. We compare directly with recent experimental findings and include in the discussion also spectral features and the effects of multiple layers

Riesgo y desarrollo técnico-científico. Sobre la importancia social de la investigación y valoración del riesgo

El tratamiento de riesgo constituye uno de los temas centrales de los estudios de CTS. Pero una completa idea de él requiere un estudio histórico. Las diferentes formas de evaluar el riesgo han mostrado que no son capaces de encontrar una unidad de medida para éste. Por lo tanto debemos concluir que esta tarea es imposible. Ello debe conducirnos hacia una nueva idea sobre las relaciones entre sociedad, ciencia y tecnología, enseñándonos que debemos convivir con la inseguridad como parte de nuestra condición.Arriskuaren tratamendua CTS ikerketen gai nagusietarikoa da. Gai horretaz ideia osoa moldatzeak azterketa historikoa eskatzen du. Arriskua ebaluatzeko era desberdinek garbi erakutsi dute ez direla gai izan hori neurketa-unitate bat aurkitzeko. Horregatik, zeregin hori ezinezkoa dela ondorioztatu behar dugu. Horrek gizartearen, zientziaren eta teknologiaren arteko harremanei buruzko ideia berri batera eraman behar gaitu, segurtasun-ezarekin bizi izan behar dugula alegia gure egoeraren alderdia del erakutsiz.Risk Management constitutes one of the central issued of CTS Studies. But a complete comprehension of that requires a historical study. Different ways of evaluation have been proposed, but none of them was capable of finding a unit of measurement. So we must conclude that there is not such a thing. That must drive us to a new idea of the interaction between society, science and technology, teaching us that we have to live with insecurity as a part of our condition

Le nouvel edifice de I'Institut für den Wissenschaftlichen Film a Göttingen

The author describes the new premises which have been built for the "Institut für den Wissenschaftlichen Film" at Göttingen. In order to provide for the needs of the present programme of work of the Institute, and for future developments as far as they can be foreseen, a wide variety of equipment has been installed.L'auteur decrit un nouvel edifice qui a ete bäti pour l'Institut für den Wissenschaftlichen Film a Göttingen. Il explique les points de vue qui ont amene a mettre sur pied les differentes installations et qui resultent du programme de travail actuel de l'Institut ainsi qüe des developpements futurs deja previsibles

Die Aufgaben des wissenschaftlichen Filmes

Auf der diesjährigen Photokina wird neben dem Bereich der wissenschaftlichen Photographie zum ersten Male auch der wissenschaftliche Film vertreten sein. Dadurch wird ein größeres Publikum mit einer Entwicklung bekanntgemacht, die sich in den letzten Jahrzehnten, besonders aber in den Jahren nach dem letzten Krieqe in Deutschland und in anderen Ländern vollzogen hat. Technische Methoden stehen schon in bemerkenswerterZahl und Qualität zur Verfügung. Was sie zu leisten vermögen, sei in lcnappen grundlegenden Ausführungen dargelegt und an einigen charakteristischen Beispielen besprochen. Verheißunqscolle Entwicklungen anderer Art beginnen sich abzuzeichnen