E-tutorial support for collaborative online learning: An explorative study on experienced and inexperienced e-tutors

The e-tutor plays a major role in supporting virtual collaborative learning, as he/she supervises learners in collaboratively solving tasks, acquiring new skills, and applying new knowledge. This study is aimed at gaining further insights into the daily support practices of e-tutors. Seventy-six e-tutors from 17 different European countries were invited to fill in an online questionnaire to evaluate collaborative activities, and to answer yes/no-questions regarding their intervention to support these collaborative activities. A cluster analysis identified two profiles of e-tutors according to the importance ascribed to collaborative activities, and to the number of times they intervened to foster such activities. The cluster validation revealed a difference between experienced and inexperienced European e-tutors in their support of online collaboration: e-tutors with experience considered specific cognitive activities to be more important for effective online collaboration, and they seemed to be more familiar in detecting and adequately intervening to avoid dysfunctional social phenomena. Thus, experience in supporting online collaboration seems to be a useful precondition for successfully intervening to stimulate necessary learning activities and to avoid dysfunctional collaborative activities.     

Progressor: social navigation support through open social student modeling

The increased volumes of online learning content have produced two problems: how to help students to find the most appropriate resources and how to engage them in using these resources. Personalized and social learning have been suggested as potential ways to address these problems. Our work presented in this paper combines the ideas of personalized and social learning in the context of educational hypermedia. We introduce Progressor, an innovative Web-based tool based on the concepts of social navigation and open student modeling that helps students to find the most relevant resources in a large collection of parameterized self-assessment questions on Java programming. We have evaluated Progressor in a semester-long classroom study, the results of which are presented in this paper. The study confirmed the impact of personalized social navigation support provided by the system in the target context. The interface encouraged students to explore more topics attempting more questions and achieving higher success rates in answering them. A deeper analysis of the social navigation support mechanism revealed that the top students successfully led the way to discovering most relevant resources by creating clear pathways for weaker students.     

The Extracellular Protease AprX from Pseudomonas and its Spoilage Potential for UHT Milk: A Review

The negative effects of proteases produced by psychrotrophic bacteria on dairy products, especially ultra‐high‐temperature (UHT) milk, are drawing increasing attention worldwide. These proteases are especially problematic, because it is difficult to control psychrotrophic bacteria during cold storage and to inactivate their heat‐resistant proteases during dairy processing. The predominant psychrotrophic species with spoilage potential in raw milk, Pseudomonas, can produce a thermostable extracellular protease, AprX. A comprehensive understanding of AprX on the aspects of its biological properties, regulation, proteolytic potential, and its impact on UHT milk can contribute to finding effective approaches to minimize, detect, and inactivate AprX. AprX also deserves attention as a representative of all extracellular metalloproteases produced by psychrotrophic bacteria in milk. The progress of current research on AprX is summarized in this review, including a view on the gap in current understanding of this enzyme. Reducing the production and activity of AprX has considerable potential for alleviating the problems that arise from the instability of UHT milk during shelf‐life.     

Bone–titanium oxide interface in humans revealed by transmission electron microscopy and electron tomography

Osseointegration, the direct contact between an implant surface and bone tissue, plays a critical role in interfacial stability and implant success. Analysis of interfacial zones at the micro- and nano-levels is essential to determine the extent of osseointegration. In this paper, a series of state-of-the-art microscopy techniques are used on laser-modified implants retrieved from humans. Partially laser-modified implants were retrieved after two and a half months'' healing and processed for light and electron microscopy. Light microscopy showed osseointegration, with bone tissue growing both towards and away from the implant surface. Transmission electron microscopy revealed an intimate contact between mineralized bone and the laser-modified surface, including bone growth into the nano-structured oxide. This novel observation was verified by three-dimensional Z-contrast electron tomography, enabling visualization of an apatite layer, with different crystal direction compared with the apatite in the bone tissue, encompassing the nano-structured oxide. In conclusion, the present study demonstrates the nano-scale osseointegration and bonding between apatite and surface-textured titanium oxide. These observations provide novel data in human specimens on the ultrastructure of the titanium–bone interface.     

Frictional testing of wood—Initial studies with a new device

In the chip refining process used for mechanical pulp production, wood fibers are treated in a narrow gap between rotating plates. The process is energy consuming and much of the electrical energy supplied to the refiner is transferred to the fiber material through friction forces. Even though the importance of friction has been discussed frequently, little has been proven due to the complexity of the process and the process conditions. This paper presents a new apparatus for studying the frictional properties of wood, in lab-scale, under conditions which are aimed at simulating those prevalent in a chip refiner. Tests can be performed in saturated steam at high temperature/pressure with sliding velocities as high as 150 m/s. Studies at room temperature showed that the friction coefficient between spruce wood and smooth steel increased with the moisture content of the specimens. Impregnation by wood extractives lowered the friction coefficient for dry wood sliding at high speed. When tests were performed in a saturated steam environment, the frictional properties were affected and varied by the temperature of the surroundings. This is interesting in view of the fact that the friction coefficient is usually considered constant in analytical and numerical models of the process.     

An Extended Method to Measure Overall Consumer Satisfaction with Packaging

There are several reasons why people find it troublesome to use and handle consumer packages. The European Committee for Standardization recently suggested a technical specification (TS) regarding packaging and ease of opening. The present study has expanded the procedure by including consumer satisfaction measurements in two steps and engaging panels comprising two separate age groups. The expanded method, which used six different packages as test objects, engaged 75 panellists, 40 in the older group (65–80 years) and 35 in the younger group (25–40 years). The expanded method not only included the same operations as described in the TS but also included panellists who graded each handling element separately on a ‘smiley’ scale, along with feedback for their grades and an overall judgement of the package handling. The grading feedback differed between the two groups. The younger panellists mainly noted issues that were not connected to openability, while older panellists noted openability as the most influential factor. Further analysis revealed that openability was also a key issue for the younger panellists, despite their claims to the contrary. Satisfaction was the most critical TS element for describing a package as being easy to open. Copyright © 2014 John Wiley & Sons, Ltd.     

Topography and performance of gas-sensing devices: An AFM study

The topography of resistive Ga₂O₃ metal oxide sensing devices was examined and characterized with an atomic force microscope (AFM). The sensing devices do not have to be destroyed for characterization and stay fully functional. Deposition of nobel metal dispersions, for example, palladium (Pd), onto the sensor surface improves its properties by adding catalytic activity. The distribution of the Pd clusters was investigated.     

Nanoscale Quantum Solvation of para-H2 Around the Linear OCS Molecule Inside 4He Droplets

We present a microscopic analysis of the quantum solvation structures of para-H₂ around the OCS molecule when embedded in low temperature ⁴He droplets. The structures of clusters containing M=5 and 6 para-H₂ molecules are compared with corresponding structures for M=1 (OCS-H₂ complex) and M=17 (a full solvation shell), as well as with the clusters in the absence of helium. We find that the helium has negligible effect on the structures for the small and large OCS(H₂) _M clusters, but that it modifies the cluster structure for M=6. We discuss implications of these resugts for the onset of superfluidity in the solvating hydrogen shell and for spectroscopic measurements.