Sustainability aspects of biobased applications : comparison of different crops and products from the sugar platform BO-12.05-002-008

In this study different uses of biomass are compared. In order to allow for a systematic comparison the study focuses on three different chemicals that can be produced from sugar. In this way it is also, in principle, possible to compare different crops for the production of the same product. The study focuses on the production of PLA (polylactic acid, a bioplastic), ethanol, and biopolyethylene (bio-PE, which is produced via ethanol). These three products can presently be produced from biomass and therefore form realistic cases. All three products are produced from sugars, and thus the systems can be decoupled at the sugar step. The sugar can be produced from different crops. In this study five different crops are compared: wheat, maize, sugar beet, sugar cane and Miscanthus. The sustainability aspects that we studied are non-renewable energy use (NREU), greenhouse gas (GHG) emission in the crop-product chain and direct land use for producing the bio-materials

Trends in student behavior in online courses

Learning management systems provide an easy and effective means of access to learning materials. Students’ access to course material is logged and the amount of interaction is assumed to be a measure of student engagement within the course. In previous research, typically frequencies of student activities have been used, but this disregards any temporal information. Here, we analyze the amount of student activity over time during courses. Based on activity data over 11 online courses, we cluster students who show similar behavior over time. This results in three different groups: a large group of students who are mostly inactive; another group of students who are very active throughout the course; and a group of students who start out being active, but their activity diminishes throughout the course. These groups of students show different performance. Overall, more active students yield better results. In addition to these general trends, we identified courses in which alternative trends can be found, such as a group of students who become more active during the course. This shows that student behavior is more complex than can be identified from an individual course and more research into patterns of learning activities in multiple courses is essential

Detectie en bestrijding van trips in de holkamer bij hyacint

Tripsen kunnen in de holkamer voor veel aantasting en schade zorgen. Het was onbekend hoeveel, wanneer en waar de tripsen voorkomen, wanneer schade optreedt en wat de beste bestrijding was. Door monitoring tussen juli en december 2006 op 12 bedrijven in De Zuid, Kennemerland en De Noord bleek dat tripsen buiten overal voorkomen. De aantallen waren zeer variabel per periode en per bedrijf. In de schuur werden maar weinig tripsen gevonden en in de holkamers was het voorkomen van tripsen uitzonderlijk. Er waren in de meeste gevallen wel aanwijsbare bronnen aan te geven voor een verhoogd risico op trips in holkamers: tomatenplanten in de schuur bij de deur, een hobbykastje met groente en sierplanten bij de buitendeur van de holkamer en holkamers zonder tripswerend gaas voor de ventilatie-openingen