The possibility to form excitons in photoilluminated correlated materials is central from fundamental and application oriented perspectives. In this paper we show how the interplay of electronelectron interactions and a magnetic superstructure leads to the formation of a peculiar spinful dark exciton, which can be detected in ARPES-type experiments and optical measurements. We study this by using matrix product states (MPS) to compute the time evolution of single-particle spectral functions and of the optical conductivity following an electron-hole excitation in a class of one-dimensional correlated band-insulators, simulated by Hubbard models with on-site interactions and alternating local magnetic fields. An excitation in only one specific spin direction leads to an additional band in the gap region of the spectral function only in the spin direction unaffected by the excitation and to an additional peak in the optical conductivity. As both is formed only after the excitation, this is interpreted as a dark exciton, which shows only in one spin direction. Recombination of the excitation happens on much longer time scales than the ones amenable to MPS. We discuss implications for experimental studies in correlated insulator systems.

This article presents an open space concept of areas that are kept permanently free from buildings, technical infrastructure, and soil sealing. In the European Alps, space is scarce because of the topography; conflicts often arise between competing land uses such as permanent settlements and commercial activity. However, the presence of open spaces is important for carbon sequestration and the prevention of natural hazards, especially given climate change. A GIS-based analysis was conducted to identify an alpine-wide inventory of large-scale near-natural areas, or simply stated, open spaces. The method used identified the degree of infrastructure development for natural landscape units. Within the Alpine Convention perimeter, near-natural areas (with a degree of infrastructural development of up to 20%) account for a share of 51.5%. Only 14.5% of those areas are highly protected and are mostly located in high altitudes of over 1500 m or 2000 m above sea level. We advocate that the remaining Alpine open spaces must be preserved through the delimitation of more effective protection mechanisms, and green corridors should be safeguarded through spatial planning. To enhance the ecological connectivity of open spaces, there is the need for tailored spatial and sectoral planning strategies to prevent further landscape fragmentation and to coordinate new forms of land use for renewable energy production.

Im Freistaat Bayern wird derzeit intensiv diskutiert, wie die nach wie vor hohe Freiflächeninanspruchnahme für Siedlungs- und Verkehrszwecke nachhaltig reduziert werden kann. Wissenschaftliche Grundlage für Steuerungsansätze in der Stadt- und Regionalentwicklung sollte ein verbessertes staatliches Flächenmonitoring sein, welches über die amtliche Flächenstatistik und deren Hauptindikator „Siedlungs- und Verkehrsfläche“ (SuV) hinaus auch die qualitative bzw. strukturelle Dimension der Flächeninanspruchnahme einbezieht. Zu diesem Zweck stellt dieser Beitrag methodische Erweiterungsansätze für das Flächenmonitoring vor, welche kleinräumige Analysen der Zersiedelung, Freiraumstruktur, Flächenversiegelung und Ökosystemleistungen am Beispiel des Landkreises Rhön-Grabfeld aufzeigen. Diese werden im Kontext der relevanten Debatten zu Ursachen und Steuerung der Flächeninanspruchnahme sowie zu aktuellen Anforderungen an das Flächenmonitoring diskutiert, sowie deren Bedeutung für das Monitoring rechtlicher Vorgaben und politischer Ziele zur nachhaltigen Flächennutzung betont.

In this article, land use change in the Tegernsee Valley in Upper Bavaria (Germany) is examined using a longitudinal analysis over 200 years. In doing so, it takes up a study by the Munich geographer Karl Ruppert from 1962. In the Tegernsee Valley, a strong change in land use has already been observed historically. The increaing settlement development can be interpreted as a result of tourism development and it is especially due to the construction of second homes. This paper documents this trend and tries to work out the reasons for the illustrated process, which is similar to what is happening in several Alpine valleys which, for topographical reasons, have scarce permanent settlement space. The methods applied include a GIS-based modelling and reconstruction of settlement development that was supplemented by the evaluation of official statistics and qualitative expert interviews in the sense of a "mixed-methods" approach. Thus, demand-and supply-oriented causes of settlement development can be explained. In addition, the current distribution and structure of second homes in the study area is presented, which was collected through onsite mapping. In this respect, instruments for limiting second homes are critically discussed, also with a comparative view of related management and planning approaches in the neigh-Längsschnittanalyse alpiner Siedlungsgeographie: Das Tegernseer Tal, Bayern 285 bouring Austrian and Swiss Alps, where similar frictions exist in dealing with scarce land resources.

No abstract