573 research outputs found
Herstellung und Charakterisierung supraleitender Nb und NbN Hot-Electron Bolometer Mischerelemente
Modularisierung als Standardisierungsprinzip. Eine Analyse zum «Mainstream» der administrativen Steuerung von Lernprozessen und Lernergebnissen in Bildungs- und Berufsbildungssystemen
Die «Modularisierung» von Bildungs- und Berufsbildungssystemen ist als eine Antwort auf eine komplexe und in hohem Maße differenzierte Systemumwelt zu verstehen. Im vorliegenden Beitrag werden die markanten Merkmale der Modularisierung erörtert. Dabei dient die Gegenüberstellung traditioneller deutscher und angelsächsischer Prinzipien in der Organisation und didaktischen Gestaltung von Bildungs- und Berufsbildungssystemen der Kennzeichnung der originären Funktionen der Modularisierung. (DIPF/Orig.)Modularisation is an answer to the growing complexity and differentiation of the environment. In this essay the main aspects of Modularisation were identified and discussed. To characterise and to point up the original determination of aims of this idea german and anglo-saxon principles in organising and arranging education and training were compared. (DIPF/Orig.
There’s something in the water - Guttation and the risk for honey bee colonies (Apis mellifera L.): a worst case semi-field scenario in maize
4.14 Developing methods for field experiments using commercially reared bumblebee colonies – initial colony strength and experimental duration as influential factors
Semi-field and field experiments with commercially used bumblebees (e.g. Bombus terrestris) gain more and more importance for both ecological studies and trials on potential side effects of plant protection products. However, standardized, replicable experimental methods are lacking so far and need further development. For example, initial strength of bumblebee colonies may vary across experiments but may be a key factor in successful colony development under field conditions. Trial duration and termination may impact results on total reproductive output (e.g. number of newly produced queens). In this study commercially reared bumblebee colonies of different initial strengths (number of worker bees) were placed along the field margin of each of six field sites. Each site was nested within one of two seasons and planted with one of two arable crops (Brassica napus and Phacelia tanacetifolia). Each colony was spaced approx. 50 m apart from the next colony, and its development was monitored once a week. While the development of half of the colonies was terminated at the first sighting of newly emerging queens within the nesting area, the other half of the colonies was left to develop further until the end of their natural colony cycle. Newly emerging queens were kept within the colonies using queen excluders. Colonies of different initial strengths showed very similar developmental patterns with medium and large colonies peaking slightly earlier than small colonies. Results may help to develop optimal parameters for standardized field tests.Semi-field and field experiments with commercially used bumblebees (e.g. Bombus terrestris) gain more and more importance for both ecological studies and trials on potential side effects of plant protection products. However, standardized, replicable experimental methods are lacking so far and need further development. For example, initial strength of bumblebee colonies may vary across experiments but may be a key factor in successful colony development under field conditions. Trial duration and termination may impact results on total reproductive output (e.g. number of newly produced queens). In this study commercially reared bumblebee colonies of different initial strengths (number of worker bees) were placed along the field margin of each of six field sites. Each site was nested within one of two seasons and planted with one of two arable crops (Brassica napus and Phacelia tanacetifolia). Each colony was spaced approx. 50 m apart from the next colony, and its development was monitored once a week. While the development of half of the colonies was terminated at the first sighting of newly emerging queens within the nesting area, the other half of the colonies was left to develop further until the end of their natural colony cycle. Newly emerging queens were kept within the colonies using queen excluders. Colonies of different initial strengths showed very similar developmental patterns with medium and large colonies peaking slightly earlier than small colonies. Results may help to develop optimal parameters for standardized field tests
Effects of neonicotinoids on honeybees, bumblebees and solitary bees in oilseed rape cultivation: Project ABO 2014
Guttation and the risk for honey bee colonies (Apis mellifera L.): a worst case semi-field scenario in maize with special consideration of impact on bee brood and brood development
Background: The possible risk of guttation for bees was investigated in two semi-field studies with maize treated with clothianidin. In a worst-case scenario set-up the effects on adult and brood mortality of bees with special consideration of the brood development of the bees were assessed. Results: Due to the weather conditions in the first experiment guttation occurred only once, which caused a high mortality and a brood-termination rate of up to 100 % in the worst-case scenario without additional water supply but no clear increase of mortality or brood termination was observed when water was supplied. In the second experiment guttation in maize occurred on 5 of 10 days. The mortality in treated variants with water supply and control variants with untreated seeds was on a similar level and within normal range. The brood-termination rate was in the control below 16 %, in the treatment from 16 to 43 %. Conclusion: In the first experiment in the variant with treated maize and no additional water supply, an artificial and extreme situation a high impact on mortality and also on the brood development was observed, indicating the sensitivity of the test system but representing an unrealistic worst case scenario. In variants with treated maize and additional water supply no clear effects on adult mortality and brood were observed in the first and the second experiment. Keywords: honey bees, guttation, pesticides, clothianidin, seed treatments, brood developmen
Verification of a new electronic bee-counting device using video analysis and manipulative trials
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