Portfolioarbeit und ihre Auswirkung auf das Hörverstehen sehr junger Englischlerner

Leeck P. Portfolioarbeit und ihre Auswirkung auf das Hörverstehen sehr junger Englischlerner. Beiträge zur Didaktik. Aachen: Shaker; 2014

Portfolio-work and its effects on listening comprehension of very young learners

At elementary school the focus often lies on listening and speaking. While listening comprehension is the basis for learning a new language, children often feel differently about that. Many measure their success in their ability to speak. Some become frustrated, because they initially are not able to express much, not noticing how much they understand already. In my research I tried to find a way to help such children appreciate more what they have achieved so far. Through portfolio-work (self-evaluation and reflection) I wanted them to see what is ‘unseen’, as well as get them to think about strategies that improve listening comprehension, as the following study report shows

The mutually exclusive expression of the 51A and 51B surface antigens of Paramecium tetraurelia

Paramecium tetraurelia stock 51 can express at least 11 different types of surface antigens, yet only a single type is found on the surface of the cell at any one time. Out of the 11 types, the 51A and 51B genes have been selected for study due to the availability of cloned versions of the 51A and 51B genes and the corresponding A-, B-deletion mutant cell lines. Analysis of wild-type stock 51 Paramecium revealed that the 51A and 51B surface antigen genes are regulated at the level of transcription. Using the cloned 51A and 51B surface antigen genes and the corresponding double mutant, a cotransformation approach was developed to address the molecular mechanisms of differential regulation. Deletion analysis of the 51A gene upstream region demonstrated that 225 base pairs of sequence are sufficient for 51A expression but 200 base pairs are not adequate for normal expression. Surprisingly, fusion gene experiments substituting regions of the 51B gene into the 51A gene showed that although upstream sequences are necessary for transcriptional activity they are not sufficient to regulate differential transcriptional control. However, substitution of sequences from the 5\sp\prime coding region of the 51B gene allowed a chimeric gene to be coexpressed with wild-type 51B. In effect, this situation was a violation of mutual exclusion and suggests that sequences within the 5\sp\prime coding region of surface antigen genes are required for mutually exclusive transcriptional control

Development of methods for structural characterization of radical cations and neutral molecules by Fourier transform ion spectrometry and characterization of the performance of a small low-field Fourier transform mass spectrometer

Structural characterization of radical cations has been an area of interest in our laboratory. The structures of long-lived low-energy molecular ions of simple carbon esters were examined by using ion/molecule reactions with selected neutral reagents (i.e., cyclohexanone, d\sb8-isopropanol and triethylamine) in an FT/ICR mass spectrometer. Reference ions with known enol or distonic structures were synthesized and their reactivity toward the neutral reagents was examined. By comparing the reactivity of the ester molecular ions to that of the reference ions, the ester radical cations were concluded to isomerize to their lowest energy isomer. Reactions of distonic dimethylene ketene radical cation were examined with several disulfide compounds as a potential method to identify the presence of disulfide bonds in neutral compounds. This ion primarily reacts by efficient thioalkyl abstraction from the disulfides. Alkyl disulfide abstraction reaction was also observed for disulfides that could yield stable tertiary or secondary alkyl radicals. From the observed reactivity, ionized dimethylene ketene was concluded to be useful for identifying disulfide bonds in neutral molecules. The performance of a small FT/ICR mass spectrometer was investigated using unscreened and screened cell designs. The use of the screened cell improves the mass range, mass accuracy and dynamic range but reduces sensitivity and trapping efficiency. Ion/molecule reactions of CH\sb3OB\sp+OCH\sb3, a fragment of ionized trimethyl borate, were examined as a potentially informative method for structural identification of neutral molecules. These reactions were examined in a low-field FT/ICR mass spectrometer. CH\sb3OB\sp+OCH\sb3 was determined to be a promising reagent to distinguish stereoisomeric diols. The cis-isomers of 1,2-cyclopentanediol and 2,3-trinorbornanediol react with CH\sb3OB\sp+OCH\sb3 to give an adduct ion that was not observed for the corresponding trans-isomers. The product, i.e., stable acylium ion, generated in the reactions of CH\sb3OB\sp+OCH\sb3 with various long-chain esters provided valuable information about the chain length of the neutral esters