Providing guidance on Backstage, a novel digital backchannel for large class teaching

Many articles in the last couple of years argued that it is necessary to promote the active participation of students in lectures with large audiences. One approach to make students actively participate in a lecture is to use a digital backchannel, i.e. a computer-mediated communication platform that allows students to exchange ideas and opinions, without disrupting the lecturer’s discourse. Though, a digital backchannel, in order to be most helpful for learning, have to address the need for guidance of the users interacting. The article presents Backstage, a digital backchannel for large class lectures, and shows how it provides guidance for its users, i.e. the students but also the lecturer. Structural guidance is provided by aligning the usually incoherent backchannel discourse with the presentation slides that are integrated in the backchannel’s user interface. The alignment is thereby asserted by carefully designed backchannel workflows. The article also discusses the guidance of a student’s substantial involvement in both the frontchannel and the backchannel by means of scripts. Through the interactions of guided individuals a social guidance may emerge, leading to a collectively regulated backchannel

Additive Fertigung frei geformter Betonbauteile durch selektives Binden mit calciumsilikatbasierten Zementen

Die additive Fertigung erlaubt ein bisher nicht gekanntes Maß an geometrischer Freiheit bei der Gestaltung von Bauteilen. In der Medizin- und Dentaltechnik wird die additive Fertigung beispielsweise eingesetzt, um an die individuelle Anatomie des Patienten angepasste Prothesen und Implantate herzustellen. Im Maschinenwesen ermöglicht sie den Bau von multifunktionalen und formoptimierten Bauteilen und damit eine Senkung des Materialeinsatzes bei gleichzeitiger Steigerung der Leistungsfähigkeit. In der Luft- und Raumfahrttechnik wird sie genutzt, um mittels Topologieoptimierung oder durch das Zusammenfassen von ganzen Baugruppen zu einem einzelnen Bauteil Gewicht zu sparen [1]. (Aus: Motivation]Additive manufacturing allows a previously unknown degree of geometric freedom in the design of components. In medical and dental technology for example, additive manufacturing is used to produce prostheses and implants adapted to the individual anatomy of the patient. In mechanical engineering, it enables the construction of multifunctional and shape-optimized components thus reducing the amount of material used while simultaneously increasing performance. In aerospace engineering, it is used to save weight by means of topology optimization or by combining entire assemblies into a single component [1]. [Off: Motivation

Vegetative growth response of young olive trees (Olea europaea L., cv. Arbequina) to soil salinity and waterlogging

28 Pag., 10 Fig. The definitive version is available at: http://www.springerlink.com/content/0032-079x/High-density olive orchards are increasing around the world, many of which may be potentially affected by salinity and waterlogging (hypoxia), two important stresses common in irrigated fields in arid and semi-arid climates. However, the response of olive to these stresses under field conditions is not well established. Therefore, our objective was to evaluate the vegetative growth response of young olive trees (Olea europaea L., cv. Arbequina) grown in a spatially-variable waterlogged, saline-sodic field. We monitored the growth in trunk diameter of 341 three-year’s old olives between September 1999 and September 2000. Field contour maps were developed delineating soil salinity (ECa), relative ground elevation (RGE) and water table depth (WTD). Soil samples were also collected and analyzed for ECe and SARe in order to characterize the salinity and sodicity profiles and develop the ECa-ECe calibration equation. The infiltration rate (IR) of the crusted and uncrusted soil and the penetration resistance (PR) were also measured. The field was characterized by spatially variable ECe (2 to 15 dS m-1), SARe (3 to 40), RGE (-4 to +4 cm) and WTD (0.5 to 1.9 m, with corresponding ground water EC values between 12 and 6 dS m-1). Steady-state IR of crusted soil was only 7% of the uncrusted soil. Since the field was heavily irrigated by flooding, waterlogging conditions were related to low RGE values. Soil salinity was negatively correlated (R2 = 0.83, P 10 dS m-1), low RGE ( 0.1 cm and > 1.6 m, respectively. Thus, very small changes in ground elevation had a significant effect on olive’s survival or death. The coupled effects of salinity and waterlogging (hypoxia) stresses were most detrimental for olive’s growth.This study was partially supported by INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain).Peer reviewe

Industrieller 3D-Betondruck durch selektive Zementaktivierung - Verfahren, Material, Anwendungen

Die selektive Zementaktivierung (SCA) ist ein additives Fertigungsverfahren zur Herstellung von Bauteilen aus Beton. Die SCA gehört zu den Verfahren des selektiven Bindens, bei denen schüttfähiges Material (hier eine Trockenmischung aus Zement und Gesteinskörnung) in dünnen Schichten ausgebracht und durch Einbringen einer flüssigen Komponente (hier Wasser) selektiv gebunden wird. Verglichen mit anderen Verfahren der additiven Fertigung mit Beton sind bei der SCA sowohl die Auflösung als auch die geometrische Freiheit besonders hoch. ...Selective cement activation (SCA) is an additive manufacturing process for the fabrication of concrete elements. SCA belongs to the group of the selective binding processes in which bulk material (here a dry mixture of cement and aggregate) is spread in thin layers and selectively bound by applying a liquid component (here water). Compared to other additive manufacturing processes using concrete, both resolution and geometric freedom are particularly high with SCA. ..

Surface plastic flow of three-dimensional printed polylactic acid in the tribological study of surface patterned polymer

The potential of three-dimensional (3D) printing in polymer tribology is poorly explored. Material alignment and composition play vital roles in altering the friction and wear characteristics of 3D printed materials. In the current study, 3D patterns made by fused deposition modelling are used to print advanced tribo-composites. Two different surface patterns (line and circular) are provided through 3D printing using white and silver polylactic acid (PLA). The deformation and distribution of white and silver PLA over the samples surface are observed after a wear test. Results showed that the coefficient of friction is not influenced by changes in the surface pattern. However, the wear rate increased for samples with line patterns on the contact surface, since plastic flow was more significant in this case. Moreover, the filling factor exhibited an influence on increasing the plastic flow of the contact surface for samples with a line pattern

New fusion rules and \cR-matrices for SL(N)qSL(N)_q at roots of unity

We derive fusion rules for the composition of $q$-deformed classical representations (arising in tensor products of the fundamental representation) with semi-periodic representations of $SL(N)_q$ at roots of unity. We obtain full reducibility into semi-periodic representations. On the other hand, heterogeneous \cR-matrices which intertwine tensor products of periodic or semi-periodic representations with $q$-deformed classical representations are given. These \cR-matrices satisfy all the possible Yang Baxter equations with one another and, when they exist, with the \cR-matrices intertwining homogeneous tensor products of periodic or semi-periodic representations. This compatibility between these two kinds of representations has never been used in physical models.Comment: 12 page

Studying Neolithic lithics – from a cross-border dialogue to a common language

This paper aims at introducing a recent European collaborative project dedicated to lithic studies of the Neolithic. It unites a group of archaeologists from France, the United Kingdom, Belgium, the Netherlands and Germany, who belong to different research traditions. Our first meetings stressed the need for a cross-border dialogue and a common language for lithic analysis, including raw material analysis, blank production and tool production. We began by highlighting the differences and proximities between the different approaches, the potentialities to bridge these differences, the archaeological goals and the training needed. Our project, therefore, aims to harmonise our study practices in order to promote international communication and collaboration.In diesem Beitrag soll ein kürzlich ins Leben gerufenes europäisches Gemeinschaftsprojekt vorgestellt werden, das sich mit lithischen Studien des Neolithikums befasst. Es vereint eine Gruppe von Archäolog*innen aus Frankreich, dem Vereinigten Königreich, Belgien, den Niederlanden und Deutschland, die unterschiedlichen Forschungstraditionen angehören. Unsere ersten Treffen verdeutlichten die Notwendigkeit eines grenzüber- schreitenden Dialogs und einer gemeinsamen Sprache für die lithische Analyse, zu der die Analyse des Rohmaterials, der Grundformproduktion und der Werkzeugproduktion gehören. Wir begannen damit, die Unterschiede und Gemeinsamkeiten zwischen den verschiedenen Ansätzen, die Möglichkeiten zur Überbrückung dieser Unterschiede, die archäologischen Ziele und die erforderliche Ausbildung herauszustellen. Unser Projekt zielt darauf ab, unsere Untersuchungspraktiken zu vereinheitlichen, um die internationale Kommunikation und Zusammenarbeit zu fördern

Experimental model of spinal cord injury in rats with a device for local therapeutic agents access

An experimental model of spinal cord injury at a precise and reproducible site is an extremely important tool for studying new therapies in spinal cord injuries. OBJECTIVES: To develop an experimental model of spinal cord injury in rats that is able to produce a complete injury (paraplegia) and placing a system enabling agents access close to injury site in order to test local therapeutic agents. METHODS: Fifteen Wistar rats were submitted to surgical transection of the spine, performed by using scissors at the level of T-13 to L-3 vertebral bodies, and, at the end of the procedure, to the insertion of a subdermal catheter intended to enable local therapeutic agents access to injury site. RESULTS: An experimental model of paraplegia was consistently developed by adding a supplementary catheter for local therapeutic agents access to injury site. CONCLUSION: An animal model of spinal cord injury and a system for local therapeutic agents access can be reproduced for the study of different modifiers of the regenerative response in a model of rats with spinal cord injury.Um modelo experimental de lesão raquimedular com localização precisa e reproduzível é uma ferramenta extremamente importante para o estudo de novas terapias em lesões raquimedulares. OBJETIVOS: Desenvolver um modelo experimental de lesão raquimedular em ratos que produza lesão completa (paraplegia) com o posicionamento de um sistema que permita o acesso de agentes próximo ao local da lesão para testar agentes terapêuticos locais. MÉTODOS: Quinze ratos Wistar foram submetidos à transecção cirúrgica da medula espinhal, realizada com o uso de tesoura ao nível dos corpos vertebrais de T-13 a L-3 e, ao final do procedimento, à implantação de um cateter subcutâneo para o acesso de agentes terapêuticos locais ao local da lesão. RESULTADOS: Um modelo experimental de paraplegia foi consistentemente desenvolvido com a adição suplementar de um cateter para o acesso de agentes terapêuticos locais ao local da lesão. CONCLUSÃO: Um modelo animal de lesão raquimedular e um sistema para o acesso de agentes terapêuticos locais pode ser reproduzido para o estudo de diferentes modificadores da resposta regenerativa em um modelo de ratos com lesão raquimedular.UNIFESPUNIFESPSciEL

Mindfulness training improves quality of life and reduces depression and anxiety symptoms among police officers : results from the POLICE study : a multicenter randomized controlled trial

Background: Police officers’ high-stress levels and its deleterious consequences are raising awareness to an epidemic of mental health problems and quality of life (QoL) impairment. There is a growing evidence that mindfulness-based interventions are efficacious to promote mental health and well-being among high-stress occupations. Methods: The POLICE study is amulticenter randomized controlled trial (RCT) with three assessment points (baseline, post-intervention, and 6-month follow-up) where police officers were randomized to mindfulness-based health promotion (MBHP) (n = 88) or a waiting list (n = 82). This article focuses on QoL, depression and anxiety symptoms, and religiosity outcomes. Mechanisms of change and MBHP feasibility were evaluated. Results: Significant group × time interaction was found for QoL, depression and anxiety symptoms, and non-organizational religiosity. Between-group analysis showed that MBHP group exhibited greater improvements in QoL, and depression and anxiety symptoms at both post-intervention (QoL d = 0.69 to 1.01; depression d = 0.97; anxiety d = 0.73) and 6-month follow-up (QoL d = 0.41 to 0.74; depression d = 0.60; anxiety d = 0.51), in addition to increasing non-organizational religiosity at post-intervention (d = 0.31). Changes on self-compassion mediated the relationship between group and pre-to-post changes for all QoL domains and facets. Group effect on QoL overall health facet at post-intervention was moderated by mindfulness trait and spirituality changes. Conclusion: MBHP is feasible and efficacious to improve QoL, and depression and anxiety symptoms among Brazilian officers. Results were maintained after 6 months. MBHP increased non-organizational religiosity, although the effect was not sustained 6 months later. To our knowledge, this is the first mindfulness-based intervention RCT to empirically demonstrate these effects among police officers. Self-compassion, mindfulness trait, and spirituality mechanisms of change are examined