Corrective Feedback in Language Learning

In the language learning classroom, teachers always provide either positive evidence or negative evidence to learners in response to the learners’ erroneous sentence (Kim, 2004). The negative evidence is also known as corrective feedback. This paper describes various types of corrective feedback provided to the learners when learning a second language (L2). We also discuss how corrective feedback facilitates language learning in five stages: notice, locate, perceive, uptake and repair. We argue that the nature of corrective feedback (explicit or implicit) has some effect how the feedback works in language learning

Where surface physics and fluid dynamics meet: rupture of an amphiphile layer by fluid flow

We investigate the fluctuating pattern created by a jet of fluid impingent upon an amphiphile-covered surface. This microscopically thin layer is initially covered with 50 $\mu$m floating particles so that the layer can be visualized. A vertical jet of water located below the surface and directed upward drives a hole in this layer. The hole is particle-free and is surrounded by the particle-laden amphiphile region. The jet ruptures the amphiphile layer creating a particle-free region that is surrounded by the particle-covered surface. The aim of the experiment is to understand the (fluctuating) shape of the ramified interface between the particle-laden and particle-free regions.Comment: published in Journal of Chemical Physic

Acoustic tests of duct-burning turbofan jet noise simulation

The results of a static acoustic and aerodynamic performance, model-scale test program on coannular unsuppressed and multielement fan suppressed nozzle configurations are summarized. The results of the static acoustic tests show a very beneficial interaction effect. When the measured noise levels were compared with the predicted noise levels of two independent but equivalent conical nozzle flow streams, noise reductions for the unsuppressed coannular nozzles were of the order of 10 PNdB; high levels of suppression (8 PNdB) were still maintained even when only a small amount of core stream flow was used. The multielement fan suppressed coannular nozzle tests showed 15 PNdB noise reductions and up to 18 PNdB noise reductions when a treated ejector was added. The static aerodynamic performance tests showed that the unsuppressed coannular plug nozzles obtained gross thrust coefficients of 0.972, with 1.2 to 1.7 percent lower levels for the multielement fan-suppressed coannular flow nozzles. For the first time anywhere, laser velocimeter velocity profile measurements were made on these types of nozzle configurations and with supersonic heated flow conditions. Measurements showed that a very rapid decay in the mean velocity occurs for the nozzle tested

Acoustic tests of duct-burning turbofan jet noise simulation: Comprehensive data report. Volume 2: Model design and aerodynamic test results

The selection procedure is described which was used to arrive at the configurations tested, and the performance characteristics of the test nozzles are given

The hen’s egg chorioallantoic membrane (HET-CAM) test to predict the ophthalmic irritation potential of a cysteamine-containing gel: quantification using Photoshop® and ImageJ.

A modified hen’s egg chorioallantoic membrane (HET-CAM) test has been developed, combining ImageJ analysis with Adobe® Photoshop®. The irritation potential of an ophthalmic medicine can be quantified using this method, by monitoring damage to blood vessels. The evaluation of cysteamine containing hyaluronate gel is reported. The results demonstrated that the novel gel formulation is non-irritant to the ocular tissues, in line with saline solution (negative control). In conclusion, the modification of the established HET-CAM test can quantify the damage to minute blood vessels. These results offer the possibility to formulate cysteamine in an ocular applicable gel formulation

Petrology of the Early Cretaceous Sierra Nevada Batholith; the Stokes Mountain region, CA

Previous studies have shown that the early Cretaceous batholith (130-110 Ma) contains the least chemically and isotopically evolved lithologies of the composite Sierra Nevada batholith. Mapping at 1:24,000 of a 360 km^2 area in the foothills ESE of Fresno (the Stokes Mountain region; latitude 36°30') reveals a smoothly continuous range (SiO_2 = 44-78%) of calcic lithologies dominated by norites, hornblende gabbros, quartz diorites, tonalites and granodiorites

Cuando la morfología y los marcadores moleculares entran en conflicto: el ejemplo de los anfípodos subterráneos de la región de Pilbara, Australia Occidental

Fifteen species of groundwater amphipods in the genus Chydaekata have been described from the Pilbara, Western Australia, each restricted to a single bore. Dewatering at a local mine site was halted while a second survey was undertaken. Newly collected samples were identified using the existing key, and allozyme analysis was used to test species boundaries. Allozymic diversity was not associated with single bores, and only two distinct genetic groups (one of which was very rare), were identified. Based on these results, and the finding that species were found to be more widespread, the Western Australian Environmental Protection Authority recommended that dewatering continue with caution at the site. This study provides an example of the problems associated with incongruent data sets, and the difficulties inherent in working with rare species, namely, interpreting the results of studies based on small samples or incomplete collections.Se han descrito quince especies de anfípodos de aguas subterráneas del género Chydaekata que habitan en la región de Pilbara, Australia Occidental, restringiéndose cada una de ellas a una única perforación. Mientras se elaboraba un segundo estudio, se interrumpió el desagüe que se estaba llevando a cabo en un emplazamiento minero local. Las nuevas muestras recolectadas se identificaron utilizando la clave existente, mientras que para verificar los límites de la especie se recurrió a un análisis alozimático. La diversidad alozimática no se asoció con perforaciones únicas y sólo se identificaron dos grupos genéticos bien diferenciados (uno de los cuales era muy poco común). Basándose en estos resultados y en el hallazgo de que la especie estaba más extendida, el Organismo de Protección Medioambiental de Australia Occidental recomendó que se actuara con cautela al proceder con el desagüe. El presente estudio brinda un ejemplo de los problemas asociados con conjuntos de datos incongruentes, así como las dificultades que conlleva trabajar con especies poco comunes, especialmente en lo que respecta a la interpretación de los resultados de estudios basados en pequeñas muestras o recolecciones incompletas

A search algorithm for quantum state engineering and metrology

In this paper we present a search algorithm that finds useful optical quantum states which can be created with current technology. We apply the algorithm to the field of quantum metrology with the goal of finding states that can measure a phase shift to a high precision. Our algorithm efficiently produces a number of novel solutions: we find experimentally-ready schemes to produce states that show significant improvements over the state-of-the-art, and can measure with a precision that beats the shot noise limit by over a factor of 4. Furthermore, these states demonstrate a robustness to moderate/high photon losses, and we present a conceptually simple measurement scheme that saturates the Cramer-Rao bound

Coined quantum walks on percolation graphs

Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections in the lattice. As a simple example of a disordered system, we consider percolation lattices, in which edges or sites are randomly missing, interrupting the progress of the quantum walk. We use numerical simulation to study the properties of coined quantum walks on these percolation lattices in one and two dimensions. In one dimension (the line) we introduce a simple notion of quantum tunneling and determine how this affects the properties of the quantum walk as it spreads. On two-dimensional percolation lattices, we show how the spreading rate varies from linear in the number of steps down to zero, as the percolation probability decreases to the critical point. This provides an example of fractional scaling in quantum walk dynamics.Comment: 25 pages, 14 figures; v2 expanded and improved presentation after referee comments, added extra figur