Förderung des computerbasierten Wissenserwerbs im Bereich empirischer Forschungsmethoden durch kooperatives Lernen und eine Feedbackmaßnahme

This study examined if computer-based learning in the field of empirical research methods could be fostered by cooperative learning and feedback. Students (n = 137) were randomly assigned to one of four experimental conditions in a 2x2-factorial design: individual learning with and without feedback intervention, and dyadic learning with and without feedback intervention. Individuals and dyads performed problem-solving tasks on correlation within a computer-based learning environment. The feedback intervention consisted of comprehension tests with elaborated feedback. In the cooperative conditions, feedback referred to the performance of the dyad, hence it was group feedback. Results showed that the feedback intervention had a substantial positive effect on learning outcomes, while cooperative learning did not significantly influence achievement. Moreover, a significant interaction effect was found: in the feedback conditions, individuals performed better than dyads; however, without the feedback intervention, dyads were more successful. For pedagogical practice it can be concluded that the feedback intervention should be implemented both in individual and cooperative computer-based learning. Especially when students learn individually, feedback is important. Further research should investigate effects of the feedback intervention in a field studIn einem Laborexperiment wurden zwei instruktionale Maßnahmen zur Förderung des computerbasierten Wissenserwerbs im Bereich empirischer Forschungsmethoden erprobt: kooperatives Lernen und Feedback. Innerhalb eines 2x2-faktoriellen Designs wurden die Faktoren "Sozialform" (individuell vs. kooperativ) und "Feedbackmaßnahme" (vorhanden vs. nicht vorhanden) variiert. 137 Studierende wurden den vier experimentellen Bedingungen zufällig zugewiesen. Die Probanden bearbeiteten innerhalb einer computerbasierten Lernumgebung allein oder zu zweit Problemlöseaufgaben zum Thema Korrelationsrechnung. Die Feedbackmaßnahme bestand aus Verständnistests mit elaboriertem Feedback. In den kooperativen Bedingungen bezog sich das Feedback auf die gemeinsame Leistung, es handelte sich also um Gruppenfeedback. Die Ergebnisse zeigen, dass der Wissenserwerb mit Hilfe der Feedbackmaßnahme substanziell gefördert werden konnte, während sich die Sozialform wider Erwarten nicht signifikant auf die Lernleistung auswirkte. Es zeigte sich weiterhin ein Interaktionseffekt der beiden Faktoren: Mit Feedback waren Individuen den Dyaden signifikant überlegen, ohne Feedback waren Dyaden deskriptiv erfolgreicher als einzelne Lernende. Für die Praxis kann gefolgert werden, dass der Einsatz der Feedbackmaßnahme sowohl beim individuellen als auch beim kooperativen computerbasierten Lernen sinnvoll ist. Besondere Bedeutung kommt dem Feedback beim individuellen Lernen zu. Für eine weitere Forschung empfiehlt sich unter anderem die Evaluation der Feedbackmaßnahme im F

Studies on the critical water mass, rehydration capability and potential, acute chill tolerance and supercooling point of Argas (Persicargas) walkerae (Acari: Argasidae)

The critical water mass, defined as the water mass remaining in a dehydrated tick in the non-ambulatory state, differed only slightly between light and heavy mass groups of Argas walkerae and averaged 23.6% and 23.2%, respectively, in males and 28.4% and 28.0%, respectively, in females. All ticks survived dehydration of 50%, 75% or 100% of their critical water mass, and 95% of them rehydrated during their subsequent incubation at 95% relative humidity (RH) and 28 degrees C for 14 days and regained their ambulatory status. Unfed adults were able to balance water loss frequently over a period of several months. When ticks were repeatedly dehydrated at 0% RH for 14 days, females and males suffered 50% mortality after 16 and 19 cycles of dehydration and rehydration, respectively, over a period of 278 days and 337 days, respectively. Water itself was not attractive to either dehydrated or non-dehydrated ticks and drinking was not observed. After submergence in water for 3 days, most of the dehydrated adult ticks gained mass. Judged by 50% mortality, larvae tolerated short-term extreme chilling to -24 degrees C, nymphs I to -22 degrees C, nymphs II to -20 degrees C, females and males to -19 degrees C. None survived tissue freezing. At a chilling rate of 0.3 degreesC/min, mean supercooling points (SCP) ranged from -25.9 degrees C in eggs to -16.5 degrees C in unfed females. The SCP of all other stages was significantly higher than that of eggs. Mean SCPs of unfed adult ticks dehydrated to 50% or 75% of their critical water mass were significantly lower than that of fully hydrated ticks. The SCPs of ticks acclimated by several weeks exposure to 0 degrees C or 38 degrees C were significantly lower than those of adult ticks kept constantly at 28 degrees C.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Application of Non‐Precious Bifunctional Catalysts for Metal‐Air Batteries

Zinc‐air batteries have several advantages in comparison with the lithium‐ion technology as they enable the use of earth‐abundant elements, work at low cost, are lightweight, and are also much safer in application. In addition to the chemistry related to the zinc electrode, efficient and stable bifunctional catalysts are required for oxygen reduction reaction (ORR, for discharging) and oxygen evolution reaction (OER, for charging) on the air‐electrode side. Herein, a family of non‐precious metal catalysts is investigated as possible bifunctional composite: metal–nitrogen–carbon (MNC) catalysts for ORR, and metal oxyhydroxides as OER catalysts (Ox). The effect of transition metal and metal loading in these composite MNC + Ox catalysts on ORR and OER activities in half‐cell measurements is discussed. The catalysts were characterized using X‐ray diffraction and Raman spectroscopy to identify their phase composition. For the most active material, a potential gap of 0.79 V between OER and ORR was obtained, respectively. In a zinc‐air cell, this catalyst moreover showed a peak power density of 62 mW cm⁻² and a charge–discharge gap of 0.94 V after 26 h of charge–discharge cycling

Influence of the Structure-Forming Agent on the Performance of Fe-N-C Catalysts

In this work, the influence of the structure-forming agent on the composition, morphology and oxygen reduction reaction (ORR) activity of Fe-N-C catalysts was investigated. As structure-forming agents (SFAs), dicyandiamide (DCDA) (nitrogen source) or oxalic acid (oxygen source) or mixtures thereof were used. For characterization, cyclic voltammetry and rotating disc electrode (RDE) experiments were performed in 0.1 M H₂SO₄. In addition to this, N₂ sorption measurements and Raman spectroscopy were performed for the structural, and elemental analysis for chemical characterization. The role of metal, nitrogen and carbon sources within the synthesis of Fe-N-C catalysts has been pointed out before. Here, we show that the optimum in terms of ORR activity is achieved if both N- and O-containing SFAs are used in almost similar fractions. All catalysts display a redox couple, where its position depends on the fractions of SFAs. The SFA has also a strong impact on the morphology: Catalysts that were prepared with a larger fraction of N-containing SFA revealed a higher order in graphitization, indicated by bands in the 2nd order range of the Raman spectra. Nevertheless, the optimum in terms of ORR activity is obtained for the catalyst with highest D/G band ratio. Therefore, the results indicate that the presence of an additional oxygen-containing SFA is beneficial within the preparation

Deutschland, Frankreich und Europa: Perspektiven

"Mit der Osterweiterung und der Baustelle des Konvents zur Zukunft Europas durchlebt die Europäische Union derzeit eine Phase des Wandels, die auch eine Prüfung darstellt. Frankreich und Deutschland müssen jetzt mehr denn je ihre Kräfte vereinen, damit dieser Wandel erfolgreich vollzogen werden kann, Europa seine inneren Konflikte überwindet und seine Rolle als globaler Akteur stärkt. In diesem Jahr feiern die beiden Länder den 40. Jahrestag der Unterzeichnung des Elysée-Vertrages. In den Monaten zuvor haben sie wieder wichtige Kompromisse geschlossen und gemeinsame Initiativen ins Leben gerufen, um in den wesentlichen europäischen Fragen voranzukommen. Auf diesem Weg sollten sie weiter vorangehen, um wieder die unverzichtbare, treibende Kraft eines auf 25 oder 27 Mitgliedstaaten erweiterten Europa zu werden. Vor diesem Hintergrund haben Ifri (Institut français des relations internationales) und DGAP, die seit vielen Jahren durch eine enge Zusammenarbeit miteinander verbunden sind, beschlossen, eine langfristig angelegte gemeinsame Analyse der Rolle des deutsch-französischen Tandems im erweiterten Europa in Gang zu bringen." (Autorenreferat

Pro Libris: Lubuskie Pismo Literacko-Kulturalne, nr 4 (2008)

172 s. : il

Digitale Schwellen: Freiheit und Privatheit in der digitalisierten Welt

Eine Welt digitaler Techniken im weitesten Sinne verändert die Kommunikationsbeziehungen, die sozialen Beziehungen der Menschen untereinander und damit auch die sozialen Verhältnisse der Menschen in der Gesellschaft in fundamentaler Weise. Wir stehen ganz offensichtlich erst an der Schwelle des Verstehens dieser komplexen und alle Lebensbereiche verändernden Revolution. Die technischen Möglichkeiten, die unser Leben ja auch erleichtern können und schöner und klüger machen, werden in großer Geschwindigkeit erweitert, immer neue Schwellen des Mach- und Denkbaren werden permanent überschritten. Redaktionsschluss: April 201

The Iceman's Last Meal Consisted of Fat, Wild Meat, and Cereals

The history of humankind is marked by the constant adoption of new dietary habits affecting human physiology, metabolism, and even the development of nutrition-related disorders. Despite clear archaeological evidence for the shift from hunter-gatherer lifestyle to agriculture in Neolithic Europe [1], very little information exists on the daily dietary habits of our ancestors. By undertaking a complementary -omics approach combined with microscopy, we analyzed the stomach content of the Iceman, a 5,300-yearold European glacier mummy [2, 3]. He seems to have had a remarkably high proportion of fat in his diet, supplemented with fresh or dried wild meat, cereals, and traces of toxic bracken. Our multipronged approach provides unprecedented analytical depth, deciphering the nutritional habit, meal composition, and food-processing methods of this Copper Age individual