Weed populations in the main cultures of Luxembourg: control options and monitoring in a complex environmental and political framework

Chemische Unkrautbekämpfung wird aufgrund von ökotoxikologischen Bedenken diskutiert. Um Landwirten zu helfen, die Ausbreitung von Unkräutern auch bei sinkender Verfügbarkeit von Herbiziden begrenzen zu können, wurden Projekte zu modifizierten Fruchtfolgen zur Reduzierung des Unkrautdruckes, digitale Ansätze für bessere Entscheidungen zum Herbizideinsatz und zur besseren Integration von nicht-chemischen Unkrautbekämpfungsmaßnahmen begonnen. In einem ersten Monitoring in den Rapsbeständen Luxemburgs wurden relativ weit verbreitete Arten wie Stellaria media, Viola arvensis, Polygonum aviculare sowie Poa annua, Elymus repens, und Apera spica-venti gefunden. Chenopodium album wurde neben den im Frühjahr keimenden Polygonum-Arten in moderater bis hoher Individuenzahl im Mais gefunden. Polygonum convolvulus wurde nach chemischer Bekämpfung in hoher Dichte am Standort Kuborn gefunden, wohingegen C. album schlecht von mechanischen Methoden bekämpft wurde. Alopecurus myosuroides-Pflanzen mit reifen Samen wurden nahezu ausschließlich im Süden Luxemburgs gefunden. Alle 35 bislang getesteten A. myosuroides Sämlingsproben waren resistent gegen Stomp® Aqua (mit dem K1 Hemmstoff Pendimethalin). Im Fall von Sigma® Maxx (mit den ALS-Inhibitoren Iodosulfuron+Mesosulfuron), waren jeweils 2 von 35 Proben sensitiv bzw. moderat resistent. 31 Proben waren resistent gegenüber Sigma® Maxx. 17 von 35 Proben waren sensitiv gegenüber Axial® (mit dem ACC-ase Inhibitor Pinoxaden), während 18 Proben resistent gegenüber Axial® waren.Due to ecotoxicological and environmental reasons, chemical treatments for weed control are under discussion. To help farmers in coping with challenges imposed by restricted herbicide availability, projects on using modified crop rotations for reducing weed pressure, digital approaches for better decision support, and a better integration of non-chemical weeding were initiated. First monitoring programs in winter oilseed rape in Luxembourg offered a preliminary overview about mainly widespread weed species like Stellaria media, Viola arvensis, Polygonum aviculare as well as Poa annua, Elymus repens and Apera spica-venti. Chenopodium album was found in moderate and high numbers in maize, as well as the spring-germinating Polygonum species. Polygonum convolvulus escaped from or re-emerged after the chemical control at location Kuborn, while C. album was poorly controlled by the mechanical treatments. Alopecurus myosuroides plants with mature seeds were almost exclusively found in the South of Luxembourg. All 35 A. myosuroides seedling samples tested so far were resistant towards Stomp® Aqua (containing the microtubule assembly inhibitor pendimethalin). In case of Sigma® Maxx (containing the ALS inhibitors iodosulfuron+mesosulfuron), 2 out of 35 samples were sensitive and moderately resistant, respectively. 31 samples were resistant to Sigma® Maxx. 17 out of 35 samples were sensitive to Axial® (containing the ACC-ase inhibitor pinoxaden), while 18 samples were resistant to Axial®

Monitoreo descriptivo de parásitos de origen fecal hallados en hortalizas de hojas

p.271-276El objetivo de este trabajo fue contabilizar la presencia de protozoos, huevos y larvas de helmintos en muestras de hortalizas de hoja para consumo fresco, que se comercializan en el Mercado Central de Buenos Aires. Las especies analizadas fueron: lechuga, radicheta, berro y perejil. Las muestras se procesaron por los métodos de Baerman y Flotación. Los resultados obtenidos indican que: 1- Existe contaminación parasitaria: sobre un total de 98 muestras analizadas durante 12 meses, el 27,5por ciento estaban contaminadas. 2- La especie más contaminada fue berro (66,7por ciento), luego radicheta (31,8por ciento), lechuga (21,4por ciento) y, finalmente, perejil (13,6por ciento). 3- El parásito más frecuente fue Entamoeba coli (44,4por ciento) y en segundo término E.hystolitica (22,4por ciento). 4- El sur y sudoeste del conurbano bonaerense fue la zona de mayor contaminación (66,6por ciento). La presencia de los contaminantes en las hortalizas estudiadas demuestra el desconocimiento de los riesgos potenciales que ciertas prácticas agrícolas pueden acarrear a los consumidores

Influence of boundary conditions on the out-of-plane response of brick masonry walls in buildings with RC slabs

In modern unreinforced masonry buildings with stiff RC slabs, walls of the top floor are most susceptible to out-of-plane failure. The out-of-plane response depends not only on the acceleration demand and wall geom-etry but also on the static and kinematic boundary conditions of the walls. This paper discusses the influence of these boundary conditions on the out-of-plane response through evaluation of shake table test results and numerical modelling. As a novum, it shows that the in-plane response of flanking elements, which are or-thogonal to the wall whose out-of-plane response is studied, has a significant influence on the vertical re-straint at the top of the walls. The most critical configuration exists if the flanking elements are unreinforced masonry walls that rock. In this case, the floor slabs can uplift, and the out-of-plane load-bearing walls loose the vertical restraint at the top. Numerical modelling confirms this experimentally observed behaviour and shows that slab uplift and the difference in base and top excitation have a strong influence on the out-of-plane response of the walls analysed

Rütteltischversuche an einem Gebäude mit Mauerwerks- und Stahlbetonwänden (Shake table tests on a building with masonry and reinforced concrete walls)

Im Rahmen eines europäischen Forschungsprojektes unter Federführung der École Polytechnique Fédérale de Lausanne (EPFL) wurde ein vierstöckiges Gebäude mit Mauerwerks-und Stahlbetonwänden auf dem Rütteltisch des TREES-Labors am EUCENTRE in Pavia (Italien) getestet. Der Test wurde im Maßstab 1:2 durchgeführt und ist Teil einer größeren Forschungsinitiative an der EPFL zu gemischten Stahlbeton-Mauerwerks-Tragsystemen. Das Hauptaugenmerk während des Rütteltischversuches lag darin, einen besseren Einblick in das dynamische, nicht-lineare Verhalten solcher gemischten Strukturen zu erhalten sowie Daten für die Validierung numerischer Modelle zu gewinnen. Dieser Beitrag stellt den Versuchskörper, die Instrumentierung und die Bodenbewegung, mit welcher der Rütteltisch angeregt wurde, dar und diskutiert erste Ergebnisse des Versuchs

New charge-transfer states in blends of ZnPC with F8ZnPC

With the aim of pushing the knowledge and understanding on mixed films of organic semiconductors forward, blends of ZnPC and F8ZnPC in different ratios are manufactured. The films have a polycrystalline structure, as indicated by electron diffraction profiles and infrared-spectroscopy. Photoluminescence data show completely different spectra for the blends, compared to the pure materials, which can be ascribed to the suppressing of excimer formation and the appearance of a new charge-transfer excitation between the two different molecules in the blends. This new excitation can also be seen in optical absorption. Momentum dependent measurements of the electronic excitations by electron energy-loss spectroscopy confirm the localized character of the new charge-transfer excitation in the blends. Our experimental data help understand the important issue of donor/acceptor coupling in organic semiconductors

Shake-table test on a four-storey structure with reinforced concrete and unreinforced masonry walls

With the introduction of higher seismic design forces in the Swiss loading standard of 2003 most unreinforced masonry (URM) buildings failed to satisfy the seismic design check. For this reason, in new construction projects, a number of URM walls are nowadays replaced by reinforced concrete (RC) walls. The lateral bracing system of the resulting structure consists therefore of URM walls and some RC walls which are coupled by RC slabs and masonry spandrels. Within the scope of a FP7-Series project a four-storey RC-URM wall structure is tested on the shake-table at the TREES laboratory of the EUCENTRE in Pavia (Italy). The test is conducted at half-scale and is part of a larger research initiative on mixed RC-URM wall systems initiated at EPFL. The key objective of the test is to gain insights into the dynamic behaviour of RC-URM wall structures and to provide input for the definition of a performance-based design approach of such mixed structural system. This paper presents details on the structural system, the instrumentation and the selected ground motion and discusses preliminary results of the shake-table test

Dynamic testing of a four-storey building with reinforced concrete and unreinforced masonry walls: Prediction, test results and data set

This paper presents the results of a series of shake-table tests on a half-scale, four-storey building with reinforced concrete (RC) and unreinforced masonry (URM) walls. Due to the lack of reference tests, the seismic behaviour of such mixed structures is poorly understood. The test unit was subjected to several runs of increasing intensity yielding performance states between minor damage and near collapse. Before the test, the expected peak table accelerations leading to different limit states were estimated using the capacity spectrum method, and the predicted values corresponded rather well to actual sustained accelerations. Next to these analyses, the paper describes the test unit, instrumentation and input motion, and comments on the response of the mixed structure in terms of damage evolution and global response quantities, such as force-displacement response and drift and acceleration profiles. The raw and post-processed data sets are made publically available, and all relevant information with regard to data organisation is described in an appendix to this paper. The test serves therefore as a benchmark for the validation of numerical models of such mixed structures. The project aims at providing a foundation for the development of seismic design and assessment methods of mixed structures, which are currently not covered by structural codes, including Eurocode 8

Validation of a Quick PCR Method Suitable for Direct Sequencing: Identification of Fusarium Fungal Species and Chemotypes for Preventive Approaches in Food Safety

Za razvoj preventivnih mjera koje se provode radi poboljšanja sigurnosti hrane neophodno je odrediti toksičnost plijesni roda Fusarium, pa se sekvenciranjem i genetskom kemotipizacijom pomoću metode lančane reakcije polimerazom određuju vrste ovoga roda plijesni. U radu je predložen brzi protokol za standardni postupak utvrđivanja vrste plijesni sekvenciranjem faktora elongacije 1α i multipleks kemotipizacijom s pomoću gena Tri12. Provedena je i statistička obrada dobivenih podataka. Kao podloga za uzgoj plijesni upotrijebljen je filter papir Miracloth, a DNA je iz plijesni izdvojena pomoću mikrovalova. Ispitano je 75 sojeva plijesni Fusarium culmorum i Fusarium graminearum, te je zaključeno da se ovim postupkom mogu uspješno odrediti vrste roda Fusarium.Species determination by sequencing and PCR genetic chemotyping, used to determine the toxigenic potential of Fusarium strains, is fundamental for developing preventive strategies in food safety. Here we propose and statistically validate a quick protocol for standardizing the procedure of species determination by sequencing of the elongation factor 1-α and multiplex genetic chemotyping using the Tri12 gene, based on fungal growth on Miracloth tissue coupled with microwave extraction. The test was validated on 75 Fusarium culmorum and Fusarium graminearum strains