Promoting self-regulated learning in web-based learning environments

Self-regulated learning with the Internet or hypermedia requires not only cognitive learning strategies, but also specific and general meta-cognitive strategies. The purposes of the Study2000 project, carried out at the TU Dresden, were to develop and evaluate authoring tools that support teachers and students in web-based learning and instruction. This paper presents how the authoring tools of the Study2000 project can implement psychologically sound measures to promote (a) active and elaborated learning activities and (b) meta-cognitive activities in a web-based learning environment. Furthermore, it describes a study involving 72 university students in the use of such a web-based learning environment in a self-regulated learning setting at the university level. Results show that students spent almost 70% of their study time with texts, 11% with learning tasks and 12% with the active and elaborated learning tools, whereas meta-cognitive aids where hardly used (<1%).     

Improved Method for Mastitis Detection and Evaluation of Disinfectant Efficiency During Milking Process

In automatic milking systems, rapid methods to detect mastitis and also to prevent mastitis are very important since reduced milk quality and economic losses are the consequences of mastitis. Based on IDF Standard 148 a rapid and reliable method to detect somatic cell count with Coulter Counter technique was developed in this study and the efficiency of peracetic acid (PAA) to prevent bacterial cross-contamination was investigated using Escherichia coli as test microorganism. Besides conventional microbiological methods, flow cytometric analysis using carboxyfluorescein diacetate, thiazole orange, propidium iodide and DiOC₂(3) were applied using E. coli as test organism to study the efficiency of PAA. Acceleration of mastitis detection method was realised using centrifugation for lipid separation of foremilk samples before Coulter Counter measurements. During inflammation, an increase in somatic cell count was detected by Coulter Counter with a peak at particle sizes between 8 and 12 μm. E. coli was reduced by 5.6 log cycles, 7.7 log cycles and 4.9 log cycles after 0.25% PAA treatment for 15 s at 0 °C, 10 °C and 20 °C. However, flow cytometric analysis showed that most of the cells are damaged but still have metabolic activity. The efficiency of PAA against mastitis-related bacteria was shown with plate count methods but flow cytometric analysis indicates that the cells may still have the potential to cause mastitis. The potential of Coulter Counter to detect somatic cell count within a short time was shown in this study. Important data regarding safety monitoring and quality control can be derived with this method.     

A function approximation approach to the segmentation step in IMRT planning

In the segmentation step of intensity modulated radiation therapy planning, given intensity profiles have to be decomposed into a number of leaf positions of a multileaf collimator (MLC) such that the superposition of the corresponding field shapes is close to the desired profile. Until now, these decomposition problems have been formulated as discrete optimization problems where the profiles are nonnegative integer matrices. The segments are modeled as 0-1-matrices, 1 indicating that radiation is transmitted through this part of the field and 0 for the areas that are covered by the leaves of the MLC. But in physical reality, radiation has a penumbra at the boundary of the segment causing a decline of the intensity, that is not modeled in these formulations. This paper embeds the segmentation task into the wider context of function approximation and models both profiles and segments as real-valued functions of two variables. This leads to convex optimization problems whose objective is to minimize the approximation error between the profile and the superposition of the real weighted segments. Thus, a more realistic model of radiation is used and may enable an improvement in treatment quality.     

Jamming of cellulose ether solutions in porous medium

The flow of aqueous cellulose ether solutions through a bead packing is investigated using magnetic resonance imaging and filtration measurements. A rather complex behavior dominated by jamming (clogging) and unjamming phenomena in time is observed. With the help of several characterization techniques (laser grain sizing, dynamic light scattering, optical microscopy, and rheometry), we find that the particular methyl(hydroxyethyl) cellulose prepared with a specific protocol, tends to form aggregates in water, even at the lowest achievable concentration. These aggregates are highly polydisperse, ranging from 100 nm to 100 μm in size, and are deformable. Their origin appears to be the hydrophobic links among molecules and the related local crystallization. It is suggested that these features play a key role in the observed jamming/unjamming during filtration tests. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3923–3935, 2015     

Polymer‐Based Spherical Activated Carbons in Combination with TS‐1 as Efficient Epoxidation Catalysts

The heterogeneously catalyzed epoxidation of commercially available biodiesel with aqueous H₂O₂ as an oxidant was studied over composite catalysts consisting of microporous titanium silicalite‐1 (TS‐1) as reactive and polymer‐based spherical activated carbon (PBSAC) as sorptive component. The results are compared to that of a commercial TS‐1 catalyst. The polymer‐based spherical activated carbon was applied either as a support or as an exotemplate. In the composite catalyst, the active titanium sites are utilized four times more efficiently than in the commercial TS‐1.     

PEAβ Triggers Cognitive Decline and Amyloid Burden in a Novel Mouse Model of Alzheimer’s Disease

Understanding the physiopathology of Alzheimer’s disease (AD) has improved substantially based on studies of mouse models mimicking at least one aspect of the disease. Many transgenic lines have been established, leading to amyloidosis but lacking neurodegeneration. The aim of the current study was to generate a novel mouse model that develops neuritic plaques containing the aggressive pyroglutamate modified amyloid-β (pEAβ) species in the brain. The TAPS line was developed by intercrossing of the pEAβ-producing TBA2.1 mice with the plaque-developing line APPswe/PS1ΔE9. The phenotype of the new mouse line was characterized using immunostaining, and different cognitive and general behavioral tests. In comparison to the parental lines, TAPS animals developed an earlier onset of pathology and increased plaque load, including striatal pEAβ-positive neuritic plaques, and enhanced neuroinflammation. In addition to abnormalities in general behavior, locomotion, and exploratory behavior, TAPS mice displayed cognitive deficits in a variety of tests that were most pronounced in the fear conditioning paradigm and in spatial learning in comparison to the parental lines. In conclusion, the combination of a pEAβ- and a plaque-developing mouse model led to an accelerated amyloid pathology and cognitive decline in TAPS mice, qualifying this line as a novel amyloidosis model for future studies.     

Two novel cyclodextrin-degrading enzymes isolated from thermophilic bacteria have similar domain structures but differ in oligomeric state and activity profile

In this paper, we present the expression and characterization of two novel enzymes from the alpha-amylase family exhibiting cyclomaltodextrinase specificity. The nucleotide sequences encoding the enzymes were isolated from the genomic DNA of two thermophilic bacterial strains originating from Icelandic hot springs and belonging to the genera Anoxybacillus (AfCda13) and Laceyella (LsCda13). The genes were amplified using a consensus primer strategy utilizing two of the four conserved regions present in glycoside hydrolase family 13. No identifiable signal peptides were present in open reading frames encoding the enzymes, indicating an intracellular location of both enzymes, and their physiological function to be intracellular cyclodextrin degradation. The domain structures of both enzymes were also similar, including an N-terminal domain, the catalytic module composed of the A- and B-domains, and a C-terminal domain. Despite the similarity in domain composition, the two enzymes displayed differences in the oligomeric state with AfCda13 being a dimeric protein, whereas LsCda13 was monomeric. The two enzymes also displayed significantly different activity profiles, despite being active on the same range of substrates. It was shown that the enzyme displaying the highest activity on cyclodextrin was dimeric (AfCda13). Moreover, a fraction of the dimeric enzyme could be converted to a monomeric state in the presence of KCl and this fraction retained only 23% of its activity on alpha-cyclodextrin while its activity on starch was not significantly affected, indicating that the oligomeric state is an important factor for a high activity on cyclodextrin substrates.