Interactions during teacher-fronted class time of English classes in a Chinese university

This research employs an ethnographic approach to examine teacher-student interaction during teacher-fronted classroom time in classrooms for English majors in a Chinese university. It involves two teachers and their respective classes. The data was collected through classroom observing, audio- and video-taping, oral report, interviewing and stimulated reflection across a two and a half month period. The data is analyzed qualitatively, using Nvivo as the main research tool and grounded theory as the approach. Informed by Vygotsky's (1978) sociocultural theory which puts talk at the core of successful teaching and learning, the analysis presented explores the patterns of interaction established in the two classes and learning opportunities embedded in them through the way the teachers interacted with their students. Erickson's (1982) constructs: academic and social participation structures, were adopted as the main frames for analyzing the data since these allow the integration of pedagogical and interactional aspects of teacher-student interaction. Analysis of the academic participation structures in the two classes revealed a traditional textbook-directed, teacher-controlled transmission mode of teaching with the focus on rote learning, vocabulary, mechanical practice, recalling from memory and knowledge rather than on language skill, meaningful interaction, understanding and method. Students were afforded fewer opportunities to participate meaningfully in classroom interaction. The teachers controlled not only the topics of academic learning but the way to learn the content. Analysis of the social participation structures showed that the teacher-student interaction was dominated by the teacher-initiated monologic IRF sequence with the I move mainly used to initiate known-information questions and the F move used to both evaluate and carry on with more instruction. The data shows how the heavy reliance on the strict IRF constrained the students' opportunities to participate in classroom discourse and to develop cognitively and linguistically. At a more general level, reliance on the IRF also shaped and constrained the students' epistemologies and learning styles. However, the picture that emerged was not all bleak. Both teachers allowed for variations to the ways the students participated, allowing the students some choice over when and how to participate. In spite of a relaxed participatory control, student initiations still rarely occurred. Consistent with the holistic nature of qualitative research, the current research also investigated contextual issues which shaped the teacher-student interaction. A range of issues were identified which largely arose from the teachers' view of language and language learning and their lack of professional development. The students were also found responsible for the interactive environment: they shared a lot of their teachers' view of language and language learning, and their cultures of learning, limited language resources and anxiety also contributed to their passive speech role, thus allowing their teachers to play a dominant role in classroom discourse unchallenged. Based on the analysis, a range of pedagogical implications have been suggested addressing academic and social participation structures and professional development of the teachers and contextual issues. The thesis concludes by proposing directions for future research

Étude et modélisation des couloirs de bus dynamiques

In cities, traffic has a significant impact on the quality of transportation systems, especially on surface public transport systems. Buses are directly slowed down by queues and congestions. They are therefore considered less punctual than other transportation modes. The d irect consequence is to strengthen the competitiveness of car. Even if bus lanes can reduce certain impacts, it potentially results in inefficient use of urban space. Therefore, it is necessary to find innovative techniques of traffic management to improve the quality of public transportation.In this perspective, this dissertation proposes to study the concept of bus lane with intermittent priority (BLIP). This system is based on the idea that opening the bus lane to general traffic intermittently when it is not in use by buses that can increase the capacity of dedicated bus lane (DBL). This variable solution will provide a bus for the time strictly necessary for each bus to pass. Hence, the competitiveness of bus is enhanced. After a review of the advanced traffic management (ATM), this new device is studied and modeled.Firstly, the activation of BLIP is discussed. Impacts on the performance of a theoretical urban arterial are analytically determined. It turns out that even if the activation seems to be counterproductive at first glance (reduces capacity and increases travel times), these costs are quickly filled by the benefits obtained downstream of the trigger area. Since bus can avoid queues at next traffic lights. This analytical study is further strengthened by a micro-simulation which is refined by taking into account more traffic physical phenomena.In the second step, we resort to an aggregated and parsimonious model of a multi-modal urban arterial to evaluate transits strategies. Such a model often provides a better understanding and valuable insights on arterial traffic dynamics. The macroscopic fundamental diagram (MFD) can play this role. Indeed, this model allows comparing different bus strategies, i.e. BLIP, DBL and bus mixed in traffic. To this end, the MFD definition is extended to account for the mean number of passenger in each mode (p-MFD). Results are used to determine the domains of application of relevant strategies in terms of traffic conditions.En milieu urbain, le trafic routier a un impact considérable sur la qualité des systèmes de transports, et en particulier, sur les transports collectifs de surface. Ainsi, les bus sont directement ralentis par les files d’attente et les congestions. Ils sont donc considérés comme moins ponctuels que les autres modes de transports. La conséquence directe est de renforcer la compétitivité du véhicule particulier par rapport aux transports en commun (TC). Même si les couloirs de bus ou les sites propres permettent de limiter les effets de la circulation, il en résulte potentiellement une utilisation inefficace de l’espace urbain pour les autres véhicules. Il est donc nécessaire d’avoir recours à des techniques innovantes de gestion du trafic pour améliorer la qualité du réseau TC.Dans cette perspective, la thèse étudie le concept de couloirs de bus dynamiques. Cette stratégie de gestion dynamique de la voirie consiste à réserver une voie au bus, lorsqu’un bus est effectivement présent. Un couloir de bus temporaire est alors créé et la compétitivité des bus vis-à-vis des autres véhicules se voit renforcée. Après un état de l’art des solutions de gestion dynamique de la voirie, ce nouveau dispositif est étudié et modélisé.Tout d’abord, la phase de déclenchement du système de couloirs de bus dynamiques est abordée. Il s’agit de déterminer analytiquement les effets sur la performance d’un boulevard urbain théorique. Il s’avère que même si la phase de déclenchement est contreproductive dans un premier temps en baissant de la capacité et augmentation des temps de parcours des véhicules. Ce coût est rapidement comblé par les bénéfices obtenus en aval de la zone de déclenchement lorsque le bus peut éviter les files d’attentes aux prochains feux de circulation. Cette étude analytique est ensuite renforcée par l’utilisation de la micro-simulation du trafic, qui donne accès à une représentation plus détaillée des phénomènes physiques du trafic urbain.Dans un second temps, un modèle agrégé et simple du fonctionnement d’un boulevard urbain multimodal est proposé. En s’appuyant sur les travaux existants concernant le diagramme fondamental macroscopique, ce modèle permet de comparer différentsaménagements (un couloir de bus dynamique et un couloir de bus permanent) avec la situation où rien n’est fait pour les bus. Les résultats obtenus permettent de déterminer les différents domaines d’application de ces aménagements en fonction des conditions de trafic

Curcumin ameliorates renal impairment in a diabetic rat model

Purpose: To investigate the molecular mechanisms of action of curcumin in regulating kidney injury in diabetic rats.Methods: Diabetes was induced in male Wistar rats by intraperitoneal administration of streptozotocin (STZ). The rats were divided into four groups, labelled as follows: blank control, positive control of curcumin-untreated STZ-rats, curcumin-treated STZ-rats (20 mg/kg), and curcumin-treated STZ-rats (50 mg/kg). After 24 weeks, blood glucose, HbA1c, mean arterial pressure (MAP), heart rates, and body weights were measured. Fasting blood samples were also collected for albumin, lipocalin-2, osteopontin, and kidney-injury-molecule 1 (KIM1) The samples were also evaluated by enzyme linked immunosorbent assay (ELISA). Rat kidneys were isolated for assessment of renal impairment by haematoxylin and eosin staining (H&E), TUNEL assays, polymerase chain reaction (PCR), and western blotting.Results: Compared with STZ group, STZ + Cur (50 mg/kg) group significantly decreased blood glucose (284.57 ± 4.28 mg/dL, p < 0.01 vs. STZ), HbA1c (5.22 ± 0.33 %, p < 0.01 vs. STZ), and MAP (76 ± 2 mmHg, p < 0.05 vs. STZ), heart rate (300 ± 6 bpm, p < 0.05 vs. STZ), and body weight (356 ± 6 g, p < 0.01 vs. STZ) were significantly increased. Kidney protein index was significantly increased, indicating improvement of renal pathological damage. The inflammatory and apoptotic cells were less than that of the STZ group in the renal tissues. The mRNA abundance and relative protein expression levels of Wnt 5a and β-catenin were also enhanced. Curcumin regulation of the Wnt signal pathway was inhibited by protease inhibitor, XAV-939.Conclusion: These results demonstrated that curcumin treatment in diabetic rats alleviates renal damage by regulating Wnt signal pathway.Keywords: Curcumin, Renal impairment, Diabetes, Wnt signal pathwa

Starch/microcrystalline cellulose hybrid gels as gastric-floating drug delivery systems

We report hybrid gels based on a high-amylose starch and microcrystalline cellulose with demonstrated properties for gastric-floating drug delivery purposes. The starch/cellulose gels were prepared by ionic liquid dissolution and regeneration, resulting in a continuous surface and a porous interior and a type-II crystalline structure of cellulose. These polysaccharide gels displayed satisfactory elasticity (0.88), recovery (0.26–0.36) and equilibrium swelling (1013–1369%). The hybrid gels were loaded with ranitidine hydrochloride as a model drug and subsequently, low-density starch/cellulose tablets were fabricated by vacuum-freeze-drying. In vitro tests in a simulated gastric fluid indicate that the 3:7 (wt./wt.) starch/cellulose system could maintain the buoyancy for up to 24 h with a release of 45.87% for the first 1 h and a sustained release for up to 10 h. Therefore, our results have demonstrated the excellent gastric-floating ability and sustainable drug release behavior of the starch/cellulose hybrid gels

Nanofiber Scaffolds with Gradations in Mineral Content for Mimicking the Tendon-to-Bone Insertion Site

We have demonstrated a simple and versatile method for generating a continuously graded, bonelike calcium phosphate coating on a nonwoven mat of electrospun nanofibers. A linear gradient in calcium phosphate content could be achieved across the surface of the nanofiber mat. The gradient had functional consequences with regard to stiffness and biological activity. Specifically, the gradient in mineral content resulted in a gradient in the stiffness of the scaffold and further influenced the activity of mouse preosteoblast MC3T3 cells. This new class of nanofiberbased scaffolds can potentially be employed for repairing the tendon-to-bone insertion site via a tissue engineering approach

Azorhizobium caulinodans c-di-GMP phosphodiesterase Chp1 involved in motility, EPS production, and nodulation of the host plant

Establishment of the rhizobia-legume symbiosis is usually accompanied by hydrogen peroxide (H2O2) production by the legume host at the site of infection, a process detrimental to rhizobia. In Azorhizobium caulinodans ORS571, deletion of chp1, a gene encoding c-di-GMP phosphodiesterase, led to increased resistance against H2O2 and to elevated nodulation efficiency on its legume host Sesbania rostrata. Three domains were identified in the Chp1: a PAS domain, a degenerate GGDEF domain, and an EAL domain. An in vitro enzymatic activity assay showed that the degenerate GGDEF domain of Chp1 did not have diguanylate cyclase activity. The phosphodiesterase activity of Chp1 was attributed to its EAL domain which could hydrolyse c-di-GMP into pGpG. The PAS domain functioned as a regulatory domain by sensing oxygen. Deletion of Chp1 resulted in increased intracellular c-di-GMP level, decreased motility, increased aggregation, and increased EPS (extracellular polysaccharide) production. H2O2-sensitivity assay showed that increased EPS production could provide ORS571 with resistance against H2O2. Thus, the elevated nodulation efficiency of the increment chp1 mutant could be correlated with a protective role of EPS in the nodulation process. These data suggest that c-di-GMP may modulate the A. caulinodans-S. rostrata nodulation process by regulating the production of EPS which could protect rhizobia against H2O2

Jitter analysis of a superconducting nanowire single photon detector

Jitter is one of the key parameters for a superconducting nanowire single photon detector (SNSPD). Using an optimized time-correlated single photon counting system for jitter measurement, we extensively studied the dependence of system jitter on the bias current and working temperature. The signal-to-noise ratio of the single-photon-response pulse was proven to be an important factor in system jitter. The final system jitter was reduced to 18 ps by using a high-critical-current SNSPD, which showed an intrinsic SNSPD jitter of 15 ps. A laser ranging experiment using a 15-ps SNSPD achieved a record depth resolution of 3 mm at a wavelength of 1550 nm.Comment: 7 pages, 6 figure