The Teachers’ voice in Saxony-Anhalt: perspectives on transition from primary to secondary school

Preparation and provision for transition between primary and secondary school get mixed reviews across all subjects. The literature suggests that modern languages is an area deserving particular attention. There are examples of good practice in transition but the general picture is, at best, patchy. Researchers (eg Blondin et al., 1998; Hill et al., 1998; Rosenbusch, 1995) confirm that this is not a country-specific issue but one which crosses borders of countries and continents. The purpose of this article is to report on how schools in Saxony-Anhalt, Germany, have dealt with the challenge of transition. The outcomes of semi-structured interviews with 25 secondary schools teachers suggest that many of the problems in Saxony-Anhalt are the same as for other countries, not least in relation to communication between secondary and primary schools and the exchange of information on individual pupils. Our German neighbours offer models of good practice in relation to Continuing Professional Development, clearly defined and understood teaching content and methods and the avoidance of any need for pupils to start their modern language learning experience afresh on arrival at secondary school

Control of serine integrase recombination directionality by fusion with the directionality factor

Bacteriophage serine integrases are extensively used in biotechnology and synthetic biology for assembly and rearrangement of DNA sequences. Serine integrases promote recombination between two different DNA sites, attP and attB, to form recombinant attL and attR sites. The ‘reverse’ reaction requires another phage-encoded protein called the recombination directionality factor (RDF) in addition to integrase; RDF activates attL × attR recombination and inhibits attP × attB recombination. We show here that serine integrases can be fused to their cognate RDFs to create single proteins that catalyse efficient attL × attR recombination in vivo and in vitro, whereas attP × attB recombination efficiency is reduced. We provide evidence that activation of attL × attR recombination involves intra-subunit contacts between the integrase and RDF moieties of the fusion protein. Minor changes in the length and sequence of the integrase–RDF linker peptide did not affect fusion protein recombination activity. The efficiency and single-protein convenience of integrase–RDF fusion proteins make them potentially very advantageous for biotechnology/synthetic biology applications. Here, we demonstrate efficient gene cassette replacement in a synthetic metabolic pathway gene array as a proof of principle

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa.

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa

Fuel Distribution Effects on Pulse Detonation Engine Operation and Performance

The validity and accuracy of performance measurements for pulse detonation engines depend on the ability to accurately measure thrust and fuel mass flow rates during system operation. Experimental tests have revealed that when fuel mass flow rates are calculated by conventional mass metering methods, incorrect values of the aggregate fuel mass in the combustor will often be calculated due to inaccurate assumptions regarding the spatial fuel distribution. The difficulty in predicting the actual fuel distribution affects the ability to achieve reliable detonations for successful operation and introduces inaccuracies directly into the performance calculations. Tunable diode laser and absorption spectroscopy techniques have been applied to provide time-resolved fuel mass fraction measurements and improve the fidelity of the specific impulse calculations. Results show that stratified fuel distributions that begin near stoichiometric at the forward end of the combustor and gradually become fuel lean near the combustor exit produce substantially higher specific impulse values than axially uniform fuel distributions with the same amount of aggregate fuel due to the ability to reliably detonate while operating at an overall lean condition. Axially uniform fuel distributions at the same average equivalence ratio demonstrated lower detonability and accordingly had lower thrust and specific impulse values.This research was supported by the Office of Naval Research with Gabriel Roy as program manager. The authors would also like to thank Jose Sinibaldi at the Naval Postgraduate School and Ma Lin from Stanford for their contributions to this effort

Performance characterization of a valveless pulse detonation engine

The article of record as published may be found at http://dx.doi.org/10.2514/6.2013-1344A valveless pulse detonation engine geometry has been partially evaluated on a direct-connect test stand at simulated inlet flight conditions to the combustor. The geometry utilizes a enriched air initiator to initiate detonations in the main combustor and has been operated on ethylene, propane, and JP-10. The initiator has been operated at frequencies up to 100 Hz. The main combustor of the engine has only been evaluated up to 30 Hz operation due to a current design constraint which will be modified to allow higher frequencies in subsequent tests. The use of an initiator required the evaluation of the diffraction limits between the initiator exit and the main combustor. The successful use of an initiator to detonate a mixture in a larger main combustor has been demonstrated. Furthermore, experimental data corroborated that tailoring the initiator to produce an overdriven detonation condition at its exit plane, enhanced the detonation transition into the larger combustor. Using imaging optical diagnostics, Mach reflections were observed at the combustor’s wall just a few centimeters downstream of the initiator’s plane. These appear to be the primary re-initiation mechanism for the re-establishment of fuel-air detonations for this geometry. Results show that a diameter ratio between the combustor and the initiator of at least will allow successful operation for ethylene and propane. Single-shot diffraction tests evaluated combustor to initiator diameter ratios up to 1.58. The specific impulse was computed from experimental measurements using both ethylene and propane fuels at various equivalent ratios from 1.0 to1.5. the results showed Isp values ranging from 850 to almost 1200 seconds, but these relative low values were anticipated due to the oversize initiator used in this study. Such a large initiator was required in order to characterize the aforementioned diameter ratios. Future tests will incorporate an optimally sized initiator, and extrapolation of the current data indicates possible Isp values as high as 1800 seconds with a stoichiometric propane - air mixture. This would indicate similar performance values to more conventionally valved PDE systems