Students’ experiences with collaborative learning in asynchronous Computer-Supported Collaborative Learning environments

This paper describes an explorative study carried out to gain response from distance students on their experiences with collaborative learning in asynchronous computer supported collaborative learning (CSCL) environments. In addition, this study also attempts to have a good grip of crucial aspects concerning collaborative learning. The study was undertaken among distance learners from the Open University of the Netherlands who were working in groups of 4–11 persons. During and after the course students’ experiences with collaborative learning were measured and after the course also students’ satisfaction with collaborative learning was assessed. The finding revealed that distance learners appreciate the opportunities to work collaboratively. They show positive experiences and are quite satisfied with collaborative learning. This study also sought to explore individuals as well as course characteristics that influenced aspects of collaborative learning, and to search aspects of collaborative learning that influenced students’ satisfaction. The findings suggested that a group product influences group process regulation and group cohesion influences students’ satisfaction with collaborative learning.     

Spontaneous reinitiation of atrial fibrillation following transvenous atrial defibrillation

Spontaneous reinitiation of atrial fibrillation (AF) has not been systematically looked at in patients undergoing transvenous AF. This study involved 11 patients, the mean age 60 +/- 8 years, 3 male and 8 female, in whom transvenous atrial defibrillation successfully converted AF to sinus rhythm. Eight patients had paroxysmal AF and three patients had chronic persistent AF for 4 weeks or more. Four patients were taking antiarrhythmic medications at the time of testing. Multipolar transvenous catheters were positioned inside the coronary sinus, right atrium, and the right ventricle. Atrial defibrillation testing was performed using the METRIX atrial defibrillation system in nine patients and the Ventritex HVSO2 in the remaining two patients. A total of 64 therapeutic shocks (range 3-11) were delivered in the 11 patients, and 31 of these successfully converted AF to sinus rhythm. In four patients spontaneous AF was reinitiated following 12 successful transvenous atrial defibrillation episodes. The mean time to reinitiation of AF following shock delivery and restoration of sinus rhythm was 8.26 +/- 5.25 seconds, range 1.8-19.9 seconds. All 12 episodes of spontaneous AF were preceded by a spontaneous premature atrial complex. The coupling interval of the premature atrial complexes was 443 +/- 43 ms, range 390-510 ms. None of the patients taking antiarrhythmic medications or those demonstrating no premature atrial complexes had spontaneous reinitiation of AF. In conclusion, spontaneous reinitiation of AF can occur in a significant proportion of patients with AF undergoing transvenous atrial defibrillation. This phenomenon is preceded by the occurrence of atrial premature complex. Findings of this study may have significant clinical implications.     

A comparison of methods for mammogram registration

Mammogram registration is an important technique to optimize the display of cases on a digital viewing station, and to find corresponding regions in temporal pairs of mammograms for computer-aided diagnosis algorithms. Four methods for mammogram registration were tested and results were compared. The performance of all registration methods was measured by comparing the distance between annotations of abnormalities in the previous and current view before and after registration. Registration by mutual information outperformed alignment based on nipple location, alignment based on center of mass of breast tissue, and warping.     

Water uptake by cocoa seeds during fermentation-like incubation

During anaerobic incubation in citric acid/NaOH (35 mmol; pH 5.5) at 40°C the fresh weight of ripe cocoa seeds (without testae) increases considerably (17–27% within 40 h) by water absorption. This is similar to water uptake during germination at 25–30°C. At 50°C in the same medium, weight increase (3.5–7.3% within 40 h) as well as net water uptake is low. Subcellular compartmentation is destroyed at 50 but not at 40°C. Since water uptake is greatly reduced or is impaired at 40°C in the presence of osmotically active substances like sucrose, it is concluded that intact vacuoles in the cotyledons are responsible for high water absorption. In the presence of acetic acid (200 mmol; 50°C) weight increase is low but loss of dry matter is increased by exudation. These findings are discussed with respect to protein vacuole swelling and proteolysis during fermentation and germination.     

Beitrag zur Kenntnis der Wechselwirkungen zwischen Proteinen und Polyphenolen der Kakaobohnen w?hrend der Fermentation

Zusammenfassung Auf Grund der Schwierigkeit, die Kakaoproteine vollständig zu extrahieren und isolieren, wurde untersucht, ob ihre beschränkte Löslichkeit in 0,2%iger KOH auf Wechselwirkungen mit Polyphenolen bei der Probenpräparation oder Fermentation beruht. Nach Vorextraktion der löslichen Polyphenole mit Aceton-Wasser-Gemischen bei tiefen Temperaturen blieben in frischen, zermahlenen Cotyledonen nur 13–15% des ursprünglichen Proteins unlöslich und nur 7–8% nach einer vorhergehenden anaeroben Wasserbehandlung, nach einer aeroben Wasserbehandlung jedoch 35 bis 40% in Abhängigkeit von den löslichen Polyphenolen.. Dieser, auf oxydativen Polyphenol-Wechselwirkungen beruhende unlösliche Rest ist im fermentierten Kakao gering. Elektrophoretisch ließen sich dementsprechend nur im ersten Falle 3 Proteinfraktionen trennen.Unter Berücksichtigung von Ergebnissen anderer Autoren wird diskutiert, ob, wie bei der Chinongerbung, Verknüpfungen zwischen chinoiden Gruppen der Polyphenole und freien Aminogruppen der Proteine angenommen werden könnten und ob eine solche Reaktion auf Grund ihrer intensiven hydrolytischen Spaltung in der anaeroben Phase der Fermentation nur an einem kleinen Teil der ursprünglichen Proteine jedoch in größerem Umfang an seinen Spaltprodukten, insbesondere Aminosäuren, erfolgt.     

Multifunctional thin film sensors based on amorphous diamond-like carbon for use in tribological applications

Amorphous diamond-like carbon films are well known for their excellent tribological properties. In this paper, we will discuss the sensoric properties of multifunctional a-C:H films with respect to force/load/pressure and temperature measurement. It turned out that nanostructured amorphous carbon films showed an impressive piezoresistive effect.Unlike well known strain gages and piezoresistive sensors, which detect a deformation of the base substrate, this novel sensor can be used in a complete stiff arrangement without any elastic joint. For film preparation, rf-plasma CVD processes were used. Besides gas pressure, a variation of the substrate power and bias potential was performed. It turned out that the tribological parameters varied slightly (hardness: 20-30 GPa, friction coefficient: 0.10 to 0.15), whereas the electrical parameters showed remarkable differences with respect to the electrical resistivity and piezoresistivity.This paper will also present different applications of amorphous carbon thin film sensors.     

Video-enhanced or textual rubrics: Does the Viewbrics' formative assessment methodology support the mastery of complex (21st century) skills?

Learners in the process of developing complex skills need a rich mental model of what such skills entail. Textual analytics rubrics (TR) are a widely used instrument to support formative assessment of complex skills, supporting feedback, reflection, and thus mental model development of complex skills. However, the textual nature of a rubric limits the possibility to deliver contextual and dynamic (time-and behaviour-oriented) information. In the Viewbrics online tool, we developed a version supporting the delivery of contextual and dynamic information by adding video-modelling examples with embedded self-explanation prompts to textual analytics rubrics. We called this combination as video-enhanced rubrics (VERs). Our current study investigates whether the Viewbrics online tool supports complex skills development and whether either textual- or video-enhanced rubrics best support complex skills' mastery. The study was a three-group (VERS n = 49, TR n = 54, control n = 50) within-subjects design. Learners' performance of complex skills was measured through expert, peer, and self-assessment using the Viewbrics online tool. A multilevel regression analysis shows learners in the TR and VERS conditions consistently outperforming the control condition to varying degrees across skills. However, no differences have been found between the two experimental conditions. Positive results across different complex skills indicate the Viewbrics online tool can be used to support the development of a wide range of complex skills in secondary education.     

Synthesis of a linear low‐density polyethylene/MgO@Mg(OH)2 nanocomposite using modified in situ polymerization

Composites of linear low‐density polyethylene were obtained in toluene slurry by in situ copolymerization of ethylene and 1‐octene in the presence of untreated magnesium oxide–hydroxide nanoparticles (MgO@Mg(OH)₂) of ±50 nm and such treated with dibutylmagnesium (DBM) as support for a bis(n‐butylcyclopentadienyl)zirconium dichloride–methylaluminoxane (MAO) catalyst system. Treatment of the nanoparticles with DBM (0.5–6 mmol g^?1 MgO@Mg(OH)₂) allows one to decrease the amount of MAO by 1.2 mmol Al g^?1 MgO@Mg(OH)₂, while reaching the same average catalyst activity and a finer distribution of the particles. Energy‐dispersive X‐ray mapping shows that the MAO is mainly associated with the filler. The crystallinity of the matrix polymer decreases with filler content. © 2018 Society of Chemical Industry