Pronunciation acquisition patterns of learners with different starting levels

This study described the results of an investigation into the effect of an intensive 12-week pronunciation course in British English which 30 Dutch female 1st-year university students of English took. They read out the same text before and after the course. Each student’s ‘before’ and ‘after’ tests were recorded. Before analysis of their results, students were split up into three groups on the basis of their general starting level: high, intermediate and low. The analysis involved a before- and after comparison of the pronunciation of eleven different phonemes: /æ, ɒ, ɔː, ʌ, ʊ, d, θ/, medial /t/, coda /r/, and syllable-final /d, v/. The analysis was done by means of both auditory and acoustic analysis. Four degrees of success (or lack thereof) were defined. The results show that the consonants required the least effort, as they were already relatively acceptable before the course started. This was true of students in general, regardless of initial starting level. The three levels of students are most distinguishable on the basis of the development of the consonants during the course. The weaker students’ consonants in particular benefitted from the course. The research revealed that initial level can be used to predict the trajectory of improvement. A general conclusion is that teachers may recognise types of students before the course starts and subject them to different types of teaching

Mobile access to moodle activities: student usage and perceptions

Parallel Sessions 4Theme: Mobile Learning MOOCs and 21st Century-learningWith the rapidly increasing use of handheld mobile devices among staff and students in higher education, it has become more and more common for them to access teaching and learning related information and services using mobile devices (Peters, 2009). A 2011 survey on mobile services in academic libraries in Hong Kong and Singapore reveals that the possession rate of mobile devices was 93.4% among Hong Kong college students, and 61.9% of them used smartphones to access the Internet (Ang, 2012). It is not uncommon to see university students use smartphones to access learning resources on Moodle and other LMSs. However, how students use Moodle via mobile phones and what their perceptions of mobile access to Moodle have rarely been formally investigated. The current research aims at filling this gap by looking at which Moodle activities students would use mobile phones to access and exploring possible reasons behind the usage patterns.postprin

Activation of AMPK by bitter melon triterpenoids involves CaMKKβ

We recently showed that bitter melon-derived triterpenoids (BMTs) activate AMPK and increase GLUT4 translocation to the plasma membrane in vitro, and improve glucose disposal in insulin resistant models in vivo. Here we interrogated the mechanism by which these novel compounds activate AMPK, a leading anti-diabetic drug target. BMTs did not activate AMPK directly in an allosteric manner as AMP or the Abbott compound (A-769662) does, nor did they activate AMPK by inhibiting cellular respiration like many commonly used anti-diabetic medications. BMTs increased AMPK activity in both L6 myotubes and LKB1-deficient HeLa cells by 20-35%. Incubation with the CaMKKß inhibitor, STO-609, completely attenuated this effect suggesting a key role for CaMKKß in this activation. Incubation of L6 myotubes with the calcium chelator EGTA-AM did not alter this activation suggesting that the BMT-dependent activation was Ca2+-independent. We therefore propose that CaMKKß is a key upstream kinase for BMT-induced activation of AMPK

Ferricytochrome c Directly Oxidizes Aminoacetone to Methylglyoxal, a Catabolite Accumulated in Carbonyl Stress

Age-related diseases are associated with increased production of reactive oxygen and carbonyl species such as methylglyoxal. Aminoacetone, a putative threonine catabolite, is reportedly known to undergo metal-catalyzed oxidation to methylglyoxal, NH4+ ion, and H2O2 coupled with (i) permeabilization of rat liver mitochondria, and (ii) apoptosis of insulin-producing cells. Oxidation of aminoacetone to methylglyoxal is now shown to be accelerated by ferricytochrome c, a reaction initiated by one-electron reduction of ferricytochrome c by aminoacetone without amino acid modifications. the participation of O-2(center dot-) and HO center dot radical intermediates is demonstrated by the inhibitory effect of added superoxide dismutase and Electron Paramagnetic Resonance spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. We hypothesize that two consecutive one-electron transfers from aminoacetone (E-0 values = -0.51 and -1.0 V) to ferricytochrome c (E-0 = 0.26 V) may lead to aminoacetone enoyl radical and, subsequently, imine aminoacetone, whose hydrolysis yields methylglyoxal and NH4+ ion. in the presence of oxygen, aminoacetone enoyl and O-2(center dot-) radicals propagate aminoacetone oxidation to methylglyoxal and H2O2. These data endorse the hypothesis that aminoacetone, putatively accumulated in diabetes, may directly reduce ferricyt c yielding methylglyoxal and free radicals, thereby triggering redox imbalance and adverse mitochondrial responses.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)INCT Processos Redox em Biomedicina (Brazil)Univ São Paulo, Dept Bioquim, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Bioquim & Biol Mol, São Paulo, BrazilUniversidade Federal de São Paulo, Inst Ciencias Ambientais Quim & Farmaceut, São Paulo, BrazilUniv São Paulo, Dept Fis & Informat, São Paulo, BrazilUniv Fed ABC, Ctr Ciencias Nat & Humanas, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Bioquim & Biol Mol, São Paulo, BrazilUniversidade Federal de São Paulo, Inst Ciencias Ambientais Quim & Farmaceut, São Paulo, BrazilWeb of Scienc

Palladacycles catalyse the oxidation of critical thiols of the mitochondrial membrane proteins and lead to mitochondrial permeabilization and cytochrome c release associated with apoptosis

Permeabilization of the mitochondrial membrane has been extensively associated with necrotic and apoptotic cell death. Similarly to what had been previously observed for B16F10-Nex2 murine melanoma cells. PdC (palladacycle compounds) obtained from the reaction of dmpa (N,N-dimethyl-1-phenethylamine) with the dppe [1,2-ethanebis(diphenylphosphine)] were able to induce apoptosis in HTC (hepatoma, tissue culture) cells, presenting anticancer activity in vitro. To elucidate cell site-specific actions of dmpa:dppe that. could respond to the induction of apoptosis in cancer cells in the present Study, we investigated the effects of PdC on isolated RLM (rat liver mitochondria). Our results showed that these -independent that these palladacycles are able to induce a Ca(2+) mitochondrial swelling that was not inhibited by ADP, Mg(2+) and antioxidants. However, the PdC-induced mitochondrial permeabilization was partially prevented by pre-incubation with CsA (cyclosporin A), NEM (N-ethylmaleimide) and bongkreic acid and totally prevented by DTT (dithiothreitol). A decrease in the content of reduced thiol groups of the mitochondrial membrane proteins was also observed, as well as the presence of membrane protein aggregates in SDS/PAGE without lipid and GSH oxidation. FTIR (Fourier-transform IR) analysis of PdC-treated RLM demonstrated the formation of disulfide bonds between critical thiols in mitochondrial membrane proteins. Associated with the mitochondrial permeabilization, PdC also induced the release of cytochrome c, which is sensitive to inhibition by DTT. Besides the contribution to clarify the pro-apoptotic mechanism of PdC, this Study shows that the catalysis of specific protein thiol cross-linkage is enough to induce mitochondrial permeabilization and cytochrome c release.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundacao de Amparo ao Ensino e Pesquisa da Universidade de Mogi das Cruzes (FAEP-UMC)UMC, CIIB, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, São Paulo, BrazilFAPESP: 98/11398-3FAPESP: 06/00995-9Web of Scienc

Dimension and projections in normed spaces and Riemannian manifolds

This thesis is concerned with the behavior of Hausdorff measure and Hausdorff dimension under projections. In 1954, Marstrand proved that given a Borel set A Ϲ R² of dimension strictly larger than 1, for almost every line L that passes through the origin, the orthogonal projection of A onto L is a set of positive Hausdorff 1-measure. This theorem marked the start of a long sequence of results in the same spirit that are nowadays known as Marstrand-type projection theorems. In the first part of this thesis, we establish Marstrand-type projection theorems for projections induced by linear foliations as well as for closest-point projections onto hyperplanes in finite dimensional normed spaces. By the same methods we obtain a Besicovitch-Federer-type characterization of purely unrectifiable sets in terms of these families of projections. Moreover, we give an example underlining the sharpness of our results. In the second part of the thesis, we establish Marstrand-type as well as Besicovitch-Federer-type projection theorems for orthogonal projections along geodesics in hyperbolic space as well as in the two-sphere. Several of these results are achievable by two different methods: potential theoretic methods and Fourier analytic methods. We discuss the scope of each of these methods in both settings

Substrate-Assisted Catalysis Unifies Two Families of Chitinolytic Enzymes

Hen egg-white lysozyme has long been the paradigm for enzymatic glycosyl hydrolysis with retention of configuration, with a protonated carboxylic acid and a deprotonated carboxylate participating in general acid-base catalysis. In marked contrast, the retaining chitin degrading enzymes from glycosyl hydrolase families 18 and 20 all have a single glutamic acid as the catalytic acid but lack a nucleophile on the enzyme. Both families have a catalytic (βα)8-barrel domain in common. X-ray structures of three different chitinolytic enzymes complexed with substrates or inhibitors identify a retaining mechanism involving a protein acid and the carbonyl oxygen atom of the substrate’s C2 N-acetyl group as the nucleophile. These studies unambiguously demonstrate the distortion of the sugar ring toward a sofa conformation, long postulated as being close to that of the transition state in glycosyl hydrolysis.