CSCL for intellectually disabled pupils: Stimulating interaction by using a floor control mechanism

Computer-supported collaborative learning has an unexploited potential of becoming an effective learning method for pupils with intellectual disabilities. This paper aims at showing how some specific requirements of this target group may be met by structuring a learning situation with the help of floor control, which restricts the opportunities of a learning dyad to act simultaneously within the learning environment. It was expected that floor control could improve communication between pupils with intellectual disabilities by explicitly structuring and restricting activities in the learning environment and making it necessary for the pupils to communicate. To examine if floor control really supports the collaboration process in the hypothesized way, two different versions of a CSCL environment were implemented and compared. The results revealed improved task-related communication and a higher quality of interaction outcomes.     

Equivalence Problems for Circuits over Sets of Natural Numbers

We investigate the complexity of equivalence problems for {∪,∩,⁻,+,×}-circuits computing sets of natural numbers. These problems were first introduced by Stockmeyer and Meyer (1973). We continue this line of research and give a systematic characterization of the complexity of equivalence problems over sets of natural numbers. Our work shows that equivalence problems capture a wide range of complexity classes like NL, C ₌ L, P,Π₂^P, PSPACE, NEXP, and beyond. McKenzie and Wagner (2003) studied related membership problems for circuits over sets of natural numbers. Our results also have consequences for these membership problems: We provide an improved upper bound for the case of {∪,∩,⁻,+,×}-circuits.     

Influence of store dimensions and auxiliary volume configuration on the performance of medium-sized solar combisystems

To increase the fractional energy savings achieved with solar thermal combisystems the store volume may be increased. Installation of large stores in single-family houses is, however, often limited by space constraints. In this article the influence of the store dimensions, as well as internal and external auxiliary volume configurations, are investigated for large solar water stores by annual dynamic TRNSYS simulations. The results show that store sizes up to 4 m³ may be used in solar heating systems with 30 m² collector area. It is further shown that well-insulated stores are rather insensitive to the geometry. Stores deviating from the conventional dimensions still yield high fractional energy savings. Furthermore, the simulations show that the performance of an internal auxiliary volume configuration in most cases exceeds that of a solution with an external auxiliary unit. The practical limitations of very thin auxiliary volumes must, however, be further investigated.     

Managing one’s identities in organisational and social settings

Interacting in the Internet, users should be empowered to use only those subsets of their personal attributes, called partial identities, which are appropriate for the actual situation and context. Refraining from acting under few and easily linkable partial identities is a prerequisite for trustworthy privacy. Traditionally user-controlled identity management systems primarily support individuals interacting with organisations, but mainly ignore special needs which arise if individuals interact with each other. To support online communities those systems have to change. From TU Dresden: Prof. Dr. Andreas Pfitzmann, head of the privacy and security group, and the research assistants Dipl.-Inform. Katrin Borcea-Pfitzmann, Dipl. Medien-inf. Katja Liesebach and Dipl.-Inform. Sandra Steinbrecher. From ULD, Kiel: Dipl.-Inform. Marit Hansen, head of PET division. Research Focus: Privacy in Identity Management and Application Design This work was funded in part by the PRIME project which receives research funding from the European Union’s Sixth Framework Programme and the Swiss Federal Office for Education and Science.     

Simulation of complex molecules—Computational requirements for the 1980''s

Improving the understanding of complex molecular systems is an important and interesting use of supercomputers. Computer simulation currently plays, and will continue to play, a vital role in research in this area by acting as a guide to site-specific mutagenesis. This study explains simulations of complex molecules.     

High‐Affinity Carbohydrate Binding by Trimeric Benzoboroxoles Measured on Carbohydrate Arrays

Carbohydrates are involved in a wide range of biological processes of pharmaceutical relevance. The selective recognition of carbohydrates is therefore of great interest in biology and medicine. In this study we present the synthesis of fluorescent multimeric benzoboroxoles and the analysis of multivalent binding processes to immobilized carbohydrate arrays by fluorescence spectroscopy. We observed high binding affinities of trimeric benzoboroxoles by determination of K_Dsurf values for their interaction with α‐Gal on glass chips. The observed K_Dsurf values were in the mid‐nM range (49 and 104 nM ) and are comparable to the K_Dsurf values for binding of natural lectins, such as that of ConA to immobilized α‐Man (79 nM ). The array technology was found to be an excellent tool for studying the binding processes of multivalent lectin mimetics with respect to profiling and quantitation.     

Reed canary grass yield and fuel quality in Estonian farmers’ fields

Reed canary grass (Phalaris arundinacea) is one of the possible raw materials for bioenergy production in northern Europe. Its cultivation is favoured because its high productivity and local origin. However, problems with the biomass quality for combustion have been reported. Usually delayed harvest in spring is suggested to improve the quality and decrease the moisture content of biomass. On the other hand, the feasibility of spring harvest depends on local climatic conditions and may cause yield losses. In current paper we studied reed canary grass fields in Estonia locating on different soil types and cultivated with various varieties. The influence of several fertilisation schemes on biomass yield was analysed. Our results indicated that production was higher on mineral soils than on the organic soil of abandoned peat extraction sites. Even different types of fertilisation did not increase the production on organic soils to the level comparable to those on mineral soils. Among studied varieties ‘Venture’ had the highest production. The highest yield per area was obtained late in the autumn (12.7 t d.w. per ha and 7.2 t d.w. per ha on mineral and organic soils, respectively). By spring the amount of biomass had decreased in all studied sites. Due to wet soil some of the fields remained unharvested, the others had high yield losses during practical harvesting. The chemical analyses did not reveal significant differences in the composition of biomass between late autumn and spring. Therefore we conclude that late autumn harvest should be preferred in local climatic conditions.     

Highly adaptable and sensitive protease assay based on fluorescence resonance energy transfer

Proteases are widely used in analytical sciences and play a central role in several widespread diseases. Thus, there is an immense need for highly adaptable and sensitive assays for the detection and monitoring of various proteolytic enzymes. We established a simple protease fluorescence resonance energy transfer (pro-FRET) assay for the determination of protease activities, which could in principle be adapted for the detection of all proteases. As proof of principle, we demonstrated the potential of our method using trypsin and enteropeptidase in complex biological mixtures. Briefly, the assay is based on the cleavage of a FRET peptide substrate, which results in a dramatic increase of the donor fluorescence. The assay was highly sensitive and fast for both proteases. The detection limits for trypsin and enteropeptidase in Escherichia coli lysate were 100 and 10 amol, respectively. The improved sensitivity for enteropeptidase was due to the application of an enzyme cascade, which leads to signal amplification. The pro-FRET assay is highly specific as even high concentrations of other proteases did not result in significant background signals. In conclusion, this sensitive and simple assay can be performed in complex biological mixtures and can be easily adapted to act as a versatile tool for the sensitive detection of proteases.