Decentralised multimedia development by the content experts

This paper describes the possibility to develop interactive educational material by the content expert (teacher). It is suggested to develop small modules of flexible material that can be easily changed similar to traditional lecture presentations. The features of such material include: • Learning by problem solving and application of knowledge (constructing knowledge). • Easy internet on-line implementation of software pieces via Shockwave technology. At the same time CD-Rom versions of the same programs can be marketed. • Integrated assessment by progress tracking and uploading via the web. • Feel of ownership (avoiding the ìnot invented here syndromeî) of the program by the teacher. • Possible exchangeability of small modules between different courses. • Built in recording of student comments for improving and debugging program for the next year • Facilitated input by students (over a year by year updating). • Teachers develop expertise in using the modern and effective teaching tools. • Teachers can put into practice much more effectively than before the educational principles learned from staff development sessions such as (self paced learning, problem based learning, deep learning, constructive learning). • Student feedback (questionnaire) indicated that > 85% of students found the program modules were more effective and more ìfunî learning than traditional method

Distribution of methanogenic potential in fractions of turf grass used as inoculum for the start-up of thermophilic anaerobic digestion

This study aims to investigate thermophilic methanogens in turf used as an inoculum. Results showed that Methanoculleus sp. regarded as hydrogenotrophic and Methanosarcina sp. regarded as acetoclastic methanogens were present in turf tested. However, active acetoclastic methanogens were present in turf soil only. The current study showed that thermophilic methanogens were present in various turf grass species: Stenotaphrum secundatum, Cynodon dactylon, and Zoysia japonica. Severe treatments of grass leaves under oxic conditions, including blending, drying and pulverizing did not affect the thermophilic hydrogenotrophic methanogenic activity of the grass. A dried and pulverized grass extract could be generated that can serve as a readily storable methanogenic inoculum for thermophilic anaerobic digestion. The methanogens could also be physically extracted into an aqueous suspension, suitable as an inoculum. The possible contribution of the presence of methanogens on grass plants to global greenhouse emissions is briefly discussed

New insights into the supression of plant pathogenic fungus (Phytophthora cinnamomi) by compost leachates

Use of compost as a soil conditioner and low-grade fertiliser is gaining popularity worldwide (Epstein, 1997). Compost not only adds plant nutrients to the soil, but also improves physical properties of soil such as buffering capacity, cation exchange capacity and water holding capacity. In addition to these benefits, compost can also suppress plant diseases caused by Phytophthora cinnamomi (Hoitink et al., 1977), Pythium aphanidermatum (Mandelbaum and Hadar, 1990), Rhizoctonia solani and Sclerotium rolfoii (Gorodecki and Hadar, 1990). Irwin et al., (1995) reported that the diseases caused by P. cinnamomi are directly responsible for considerable economic losses in many horticultural, ornamental and forestry industries throughout Australia. Phytophthora spp. continue to be the focus of attention of many researchers due to the diversity of P. cinnamomi-host interactions and their potential economic impact on a wide range of industries. The practise of using methyl bromide and other chemicals for disinfection of soil is widespread (Trill as et al., 2002). However, the use of methyl bromide and other chemicals is phased out in the USA and Europe. The suppression of soil-borne plant fungus by composts produced from tree barks (Spencer et al., 1982) and municipal solid wastes is well documented (Trill as et al., 2002). Composts that suppress plant disease have been extensively described and are used in greenhouse production systems (Lazarovitis et aI, 2001). However, most studies have focused on compo sting different types of materials and their effect on fungal pathogens inhibition rather than compo sting conditions that may produce suppressive composts. An objective of this study was to investigate the role of moisture, aeration and compost maturity in enhancing the inhibition effect of compost on the plant pathogen P. cinnamomi. A further objective was to generate an increased understanding of the mechanism of growth inhibition

Mathematik lernen und unterrichten in der Grundschule

Anlass für diesen Beitrag ist die Frage, was in der Mathematikdidaktik seit Verabschiedung der Bildungsstandards 2004 eigentlich erreicht wurde und welche Forschungslücken zu konstatieren sind. Mein Blick auf dieses Thema ist ein spezifischer: Als Sonderpädagogin blicke ich primär psychologisch auf das individuelle Lernen, als Soziologin dann sekundär auf dieses individuelle Lernen im sozialen Umfeld. Mit diesem Fokus betrachte ich die prozessbezogenen Kompetenzbereiche der Bildungsstandards. Diese Konzentration auf die allgemeinen Kompetenzen ist vorrangig motiviert als Gegengewicht zu dem häufig inhaltlichen Blick, in welchem die prozessbezogenen Kompetenzen lediglich begleitende Funktion einnehmen. Alle fünf Kompetenzbereiche sollen betrachtet werden. Ausgehend von den formulierten Erwartungen in den Bildungsstandards werden wenige Hauptpunkte des jeweiligen Gebietes thematisiert und grundlegende offene Fragen aufgeworfen. Insofern warne ich davor, Vollständigkeit zu erwarten

Biology of anaerobic bacteria

Sulfate reducing bacteria of the genus DESULFOVIBRIO and homoacetogenic bacteria of the genus SPOROMUSA were sensitive to changes of hydrogen concentrations during the growth on an organic substrate. Increase of hydrogen concentrations competitively inhibited the organic substrate degradation and decrease of hydrogen concentration inhibited the respiration and the reduction of the external electron acceptor. Such hydrogen sensitive strains which seem to intermediarily produce and consume hydrogen ("hydrogen-cycling") were cultivated in the presence of a second hydrogen oxidizer. Both organisms competed for the hydrogen excreted by the first strain. The competence for H2-oxidation of the strains depended not only on hydrogenase affinities but also on the free energy change of H2-oxidation differing with the respective electron acceptors. (Résumé d'auteur

Characterisation of GNSS carrier phase data on a moving zero-baseline in urban and aerial navigation

We present analyses of Global Navigation Satellite System (GNSS) carrier phase observations in multiple kinematic scenarios for different receiver types. Multi-GNSS observations are recorded on high sensitivity and geodetic-grade receivers operating on a moving zero-baseline by conducting terrestrial urban and aerial flight experiments. The captured data is post-processed; carrier phase residuals are computed using the double difference (DD) concept. The estimated noise levels of carrier phases are analysed with respect to different parameters. We find DD noise levels for L1 carrier phase observations in the range of 1.4–2 mm (GPS, Global Positioning System), 2.8–4.6 mm (GLONASS, Global Navigation Satellite System), and 1.5–1.7 mm (Galileo) for geodetic receiver pairs. The noise level for high sensitivity receivers is at least higher by a factor of 2. For satellites elevating above 30◦, the dominant noise process is white phase noise. For the flight experiment, the elevation dependency of the noise is well described by the exponential model, while for the terrestrial urban experiment, multipath and diffraction effects overlay; hence no elevation dependency is found. For both experiments, a carrier-to-noise density ratio (C/N0) dependency for carrier phase DDs of GPS and Galileo is clearly visible with geodetic-grade receivers. In addition, C/N0 dependency is also visible for carrier phase DDs of GLONASS with geodetic-grade receivers for the terrestrial urban experiment. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Bio-Electrochemical Sensor for Fast Analysis of Assimilable Organic Carbon in Seawater

A Microbial Fuel Cell (MFC) based biosensor for the determination of Assimilable Organic Carbon (AOC) inseawater was developed by establishing an anodophilic marine biofilm on the surface of an electrode poised at +250mV (vs Ag/AgCl) rather than the traditionally used potentials of about -300 mV. A linear correlation (R2>0.99)between electrochemical signals (peak current) and acetate concentration ranging 10 to 55 μM was achieved.Usingthe positive anodic potential enabled the rapid establishment of the electrochemically active anodophilic biomasswithin a period of less than 8 days, a higher sensitivity (0.017 mA/μM acetate added) and a lower detection limit (2.5μM acetate, 0.16 mg O2/L of Biological Oxygen Demand (BOD)) compared to the negative anodic potential. Further,it was shown that this bio-electrochemical AOC sensor could tolerate the presence of low concentrations ofdissolved oxygen. The established potentiostat controlled MFC biosensor could be used for the purpose of onlinewater quality monitoring for seawater desalination plants prone to biofouling of RO membranes