On the practicality of group dynamic assessment: A seminal enterprise deserving closer scrutiny

This is the final version of the article. Available from the publisher via the DOI in this record.This paper is a preliminary study designed to scrutinize the way Group Dynamic Assessment (G-DA), suggested by Poehner (2009), has been implemented in L2 classrooms regarding its basic premise: moving the group forward in its ZPD while benefiting individuals as well. Since the one-to-one interaction that characterizes DA framework represents an unrealistic model for classroom teachers who must manage classes of 15 to 30 learners, Poehner (2009) suggests the use of DA with groups of L2 learners rather than individuals and offers examples of two approaches to G-DA: concurrent and cumulative. However, the development of group ZPD cannot be easily traced in the presented approaches, and the process of shifting the activity from the individual to the group is not clarified either. To present a more realistic model of G-DA, this paper suggests the application of small group DA to L2 classrooms. To this end, it has initially delved into the concepts of 'group learning', 'group ZPD', and 'group DA'. Next, the areas of ambiguity in the two suggested approaches to G-DA have been identified. Finally, a less complicated model of classroom DA, namely small group DA is presented

Wildfire risk forecasting using weights of evidence and statistical index models

The risk of forest and pasture fires is one of the research topics of interest around the world. Applying precise strategies to prevent potential effects and minimize the occurrence of such incidents requires modeling. This research was conducted in the city of Sanandaj, which is located in the west of the province of Kurdistan and the west of Iran. In this study, fire risk potential was assessed using weights of evidence (WoE) and statistical index (SI) models. Information about fire incidents in Sanandaj (2011–2020) was divided into two parts: educational data (2011–2017) and validation data (2018–2020). Factors considered for potential forest and rangeland fire risk in Sanandaj city included altitude, slope percentage, slope direction, distance from the road, distance from the river, land use/land cover (LULC), average annual rainfall, and average annual temperature. Finally, in order to validate the two models used, the receiver operating characteristic (ROC) curve was used. The results for the WoE and SI models showed that about 62.96% and 52.75% of the study area, respectively, were in the moderate risk to very high risk classes. In addition, the results of the ROC curve analysis showed that the WoE and SI models had area under the curve (AUC) values of 0.741 and 0.739, respectively. Although the input parameters for both models were the same, the WoE model showed a slightly higher AUC value compared to the SI model, and can potentially be used to predict future fire risk in the study area. The results of this study can help decision makers and managers take the necessary precautions to prevent forest and rangeland fires and/or to minimize fire damage

Comparison of two purified toxic fractions from Mesobuthus eupeus scorpion venom

Iranian scorpions belong mainly to the Buthidae and Scorpionidae families, distributed into 16 genera and 25 species. In Iran, similar to other parts of the world, there are a few known species of scorpions responsible for severe envenoming; amongst which Mesobuthus eupeus is the most common. Its venom contains several toxin fractions that may affect the ion channel. In the present study purification, labeling and biological evaluation of M. eupeus venom are described. For separation, soluble venom was loaded on a chromatography column packed with Sephadex G-50 gel. Subsequently, the fractions were collected according to UV absorption at a wavelength of 280 nm. Toxic fraction (F3) was loaded on an anionic ion exchanger resin and then on a cationic resin. Finally, toxic subfractions F3.1.6 and F3.1.9 were labeled with 99mTc and injected into normal mice to distinguish excretion pathway. The venom toxic fraction was successfully obtained in its purified form. Radiolabeling of toxic fractions was performed at high specific activity with radiochemical purity of more than 97 and 95% respectively for F3.1.6 and F3.1.9. Biodistribution studies in normal mice with two toxic fractions usually show rapid clearance of the compounds from blood and tissue except for kidneys. Since tissue distribution studies are very important for clinical purpose, the present findings suggest that 99mTc labeling of venom is a useful tool for in vivo studies and comprises an excellent approach to monitoring the process of biodistribution and kinetics of toxins

Frictional behaviour of AA7075-O aluminium alloy in high speed tests

The influence of strain rate on the frictional behaviour of AA7075 aluminium alloy, in the O-annealed temper state, was studied. The attention was focused on the evaluation of the mechanisms affecting friction at high strain rate. To this purpose, axisymmetric and ring compression tests were carried out using the split Hopkinson tension-compression bar in the direct version. The flow curves were investigated in a wide range of strain rate using cylindrical specimens characterised by different slenderness ratios. The results of the axisymmetric compression tests showed an appreciable strain rate sensitivity of the deforming material with a marked increase in flow stress with strain rate in the dynamic loading condition. As far as the ring compression tests are concerned, different strain rates were obtained using hollow cylinders with different initial sizes. The analysis of the results showed that strain rate affects the variation of the inner ring diameter, irrespective of the height reduction and frictional condition. Axysimmetric and ring compression tests were also performed under the quasi-static loading condition and the experimental results did not show any appreciable effect of strain rate on flow curves and frictional behaviour. Finally, the different frictional behaviour between the quasi-static and dynamic loading conditions was attributed both to the reduction in the lubricant film thickness and change in the viscous actions at the specimen-tool interface