Design, Realisierung und Anwendung hochfrequenter diffraktiv-optischer Elemente und deren Kombination für neue mikrooptische Module

Das Beugungsverhalten hochfrequenter Gitterstrukturen in dielektrischen Materialien wird mittels rigoroser Beugungstheorien (RCWA, RMA) analysiert und durch Vermessung in die Oberfläche planarer Quarzsubstrate geätzter Gitterstrukturen verifiziert. Für zero-order Gitter erfolgt ein Vergleich mit Ergebnissen der effektiven Mediumtheorie (EMT). Für binäre oberflächenkorrigierte Gitter, d. h. mit rechteckförmigen Stegprofil, werden globale Effizienzmaxima (bis zu 99.99 %) bei Bragg-Einfall in Abhängigkeit der Gitterperiode ausführlich diskutiert. Anwendungen als Strahlablenker, (Polarisations-) Strahlteiler, lambda/4- und lambda/2-Phasenplatte, nanooptischer Schalter und als diffraktiver nanooptischer Isolator werden theoretisch optimiert, die Propagation endlicher Strahlbündel durch derartige Gitterstrukturen wird numerisch simuliert und die Ergebnisse werden experimentell verifiziert

Methoden zur Charakterisierung optischer Gitter über einen großen Ortsfrequenzbereich

In unserem Beitrag berichten wir über Methoden zur Streulicht- und Wellenfrontmessung optischer Gitter. Ein selbst entwickelter Streulichtmessplatz in der Czerny-Turner-Geometrie erlaubt die Messung von BRDF-Werten über bis zu 14 Größenordnungen mit hoher Winkel-Auflösung. Zur quantitativen Erfassung von Wellenfrontfehlern holografisch-abbildender Gitter wird ein Moiré-Verfahren verwendet

Time spent on work-related activities, social activities and time pressure as intermediary determinants of health disparities among elderly women and men in 5 European countries: a structural equation model

Background Psychosocial factors shape the health of older adults through complex inter-relating pathways. Besides socioeconomic factors, time use activities may explain gender inequality in self-reported health. This study investigated the role of work-related and social time use activities as determinants of health in old age. Specifically, we analysed whether the impact of stress in terms of time pressure on health mediated the relationship between work-related time use activities (i.e. housework and paid work) on self-reported health. Methods We applied structural equation models and a maximum-likelihood function to estimate the direct and indirect effects of psychosocial factors on health using pooled data from the Multinational Time Use Study on 11,168 men and 14,295 women aged 65+ from Italy, Spain, UK, France and the Netherlands. Results The fit indices for the conceptual model indicated an acceptable fit for both men and women. The results showed that socioeconomic status (SES), demographic factors, stress and work-related time use activities after retirement had a significant direct influence on self-reported health among the elderly, but the magnitude of the effects varied by gender. Social activities had a positive impact on self-reported health but had no significant impact on stress among older men and women. The indirect standardized effects of work-related activities on self-reported health was statistically significant for housework (β = − 0.006; P  0.05 among women), which implied that the paths from paid work and housework on self-reported health via stress (mediator) was very weak because their indirect effects were close to zero. Conclusions Our findings suggest that although stress in terms of time pressure has a direct negative effect on health, it does not indirectly influence the positive effects of work-related time use activities on self-reported health among elderly men and women. The results support the time availability hypothesis that the elderly may not have the same time pressure as younger adults after retirement

Wissen machen - Beiträge zu einer Geschichte erziehungswissenschaftlichen Wissens in Deutschland zwischen 1945 und 1990. Einleitung zum Beiheft

Die HerausgeberInnen des Beiheftes stellen in der Einleitung die Beiträge des Bandes und deren wissensgeschichtlichen Ansatz dar. In diesen wird sichtbar, dass eine Nutzung wissenschaftlichen Wissens über Bildung und Erziehung in der Politikberatung und durch bildungspolitische Akteure dazu führte, dass Wissen Grenzen zwischen unterschiedlichen Subsystemen überschritt, dass \u27Zirkulationen von Wissen\u27 stattfanden. Aber auch die Produktion wissenschaftlichen Wissens selbst fand nicht in einem politikfreien Raum statt, sondern war selbst in ihren epistemologischen und methodologischen Grundlagen beeinflusst von \u27außerwissenschaftlichen\u27 Faktoren, von organisationalen und materiellen Bedingungen. (DIPF/Orig.

Implications of the proposed Soil Framework Directive on agricultural systems in Atlantic Europe – a review

peer-reviewedThe main threats to soils outlined in the pending Soil Framework Directive (SFD) are: contamination, loss of organic matter, erosion, compaction, sealing, salinization and desertification. The first four threats are pertinent to agricultural systems in Atlantic Europe, but vary in their extent between countries depending on the spatial soil distribution. Loss of soil biodiversity has not been included as a potential threat in the SFD due to lack of information that is currently available both spatially and temporally to facilitate any legislation to protect it. This paper gives emphasis to the four main threats outlined above associated with Agricultural systems in Atlantic Europe. Each soil threat is discussed in relation to the agricultural management calendar for cultivated and grazed grassland soils. The paper discusses current soil protection policies and possible changes to such legislation with the adoption of the SFD by member states