GRI: The Gamma-Ray Imager mission

With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction have paved the way towards a new gamma-ray mission, providing major improvements regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow studies of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.Comment: 8 page

Strittiges und Unbestreitbares in der Architekturentwicklung der DDR in den 50er Jahren

Wissenschaftliches Kolloquium vom 5. bis 7. Juli 1983 in Weimar an der Hochschule für Architektur und Bauwesen zum Thema: 'Das Bauhauserbe und die gegenwärtige Entwicklung der Architektur : zum 100. Geburtstag von Walter Gropius

Structure and diffusion in amorphous aluminium silicate: A molecular dynamics computer simulation

The amorphous aluminium silicate (Al2O3)2(SiO2) [AS2] is investigated by means of large scale molecular dynamics computer simulations. We consider fully equilibrated melts in the temperature range 6100K >= T >= 2300K as well as glass configurations that were obtained from cooling runs from T=2300K to 300K with a cooling rate of about 10^12K/s. Already at temperatures as high as 4000K, most of the Al and Si atoms are four-fold coordinated by oxygen atoms. Thus, the structure of AS2 is that of a disordered tetrahedral network. The packing of AlO4 tetrahedra is very different from that of SiO4 tetrahedra in that Al is involved with a relatively high probability in small-membered rings and in triclusters in which an O atom is surrounded by four cations. We find as typical configurations two-membered rings with two Al atoms in which the shared O atoms form a tricluster. On larger length scales, the system shows a microphase separation in which the Al-rich network structure percolates through the SiO2 network. The latter structure gives rise to a prepeak in the static structure factor at a wavenumber q=0.5\AA^{-1}. The comparison of experimental X-ray data with the results from the simulation shows a good agreement for the structure function. The diffusion dynamics in AS2 is found to be much faster than in SiO2. We show that the self-diffusion constants for O and Al are very similar and that they are by a factor of 2-3 larger than the one for Si.Comment: 30 pages of Latex, 13 figure

Engineering of Neutral Excitons and Exciton Complexes in Transition Metal Dichalcogenide Monolayers through External Dielectric Screening

In order to fully exploit the potential of transition metal dichalcogenide monolayers (TMD-MLs), the well-controlled creation of atomically sharp lateral heterojunctions within these materials is highly desirable. A promising approach to create such heterojunctions is the local modulation of the electronic structure of an intrinsic TMD-ML via dielectric screening induced by its surrounding materials. For the realization of this non-invasive approach, an in-depth understanding of such dielectric effects is required. We report on the modulations of excitonic transitions in TMD-MLs through the effect of dielectric environments including low-k and high-k dielectric materials. We present absolute tuning ranges as large as 37 meV for the optical band gaps of WSe 2 and MoSe 2 MLs and relative tuning ranges on the order of 30% for the binding energies of neutral excitons in WSe 2 MLs. The findings suggest the possibility to reduce the electronic band gap of WSe 2 MLs by 120 meV, paving the way towards dielectrically defined lateral heterojunctions.Comment: 11 pages + 6 pages supporting informatio

Strittiges und Unbestreitbares in der Architekturentwicklung der DDR in den 50er Jahren

Wissenschaftliches Kolloquium vom 5. bis 7. Juli 1983 in Weimar an der Hochschule für Architektur und Bauwesen zum Thema: 'Das Bauhauserbe und die gegenwärtige Entwicklung der Architektur : zum 100. Geburtstag von Walter Gropius

Das soziale Moment in den Architekturanschauungen Ernst Mays in den 20er Jahren

Wissenschaftliches Kolloquium vom 24. bis 26. Juni 1986 in Weimar an der Hochschule für Architektur und Bauwesen zum Thema: 'Der wissenschaftlich-technische Fortschritt und die sozial-kulturellen Funktionen von Architektur und industrieller Formgestaltung in unserer Epoche

Thesen zum Workshop: Die Architektur ist ein Gestaltungsprozeß des sozialen Lebens der Gesellschaft - Werk, Erbe und geschichtlicher Rang des Architekten und Urbanisten Hannes Meyer : Betrachtungen anläßlich seines 100. Geburtstages

Wissenschaftliches Kolloquium vom 27. bis 30. Juni 1989 in Weimar an der Hochschule für Architektur und Bauwesen zum Thema: ‚Produktivkraftentwicklung und Umweltgestaltung. Sozialer und wissenschaftlich-technischer Fortschritt in ihren Auswirkungen auf Architektur und industrielle Formgestaltung in unserer Zeit. Zum 100. Geburtstag von Hannes Meyer

Hannes Meyer - Anmerkungen zu Leben und Werk

Wissenschaftliches Kolloquium vom 27. bis 30. Juni 1989 in Weimar an der Hochschule für Architektur und Bauwesen zum Thema: ‚Produktivkraftentwicklung und Umweltgestaltung. Sozialer und wissenschaftlich-technischer Fortschritt in ihren Auswirkungen auf Architektur und industrielle Formgestaltung in unserer Zeit. Zum 100. Geburtstag von Hannes Meyer