553 research outputs found

    Towards a responsible agenda for academic literacy development: considerations that will benefit students and society

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    The transition from secondary to higher education (HE) requires a change of cultural mindset (cf. Darlaston-Jones et al., 2003; Leki, 2006). It is widely accepted that the academic performance and motivation of first year students to stay in HE depend, among others, on how well they integrate into the university environment (Brinkworth et al., 2009). Academic integration or acculturation takes different forms. The premise of this article is that students have to learn to engage with academic discourse, i.e., they must acquire the community’s communicative currency, defined as different kinds of language used to reflect the community’s current norms, practices, values and expectations (cf., among others, Duff, 2010; Gee, 1998, 2000; Hyland, 2009). As reflective and responsible practitioners we therefore need to outline a critical agenda for academic acculturation by reviewing the debate on the nature of literacy and,  particularly, by discussing similarities and differences in epistemology and approaches to literacy. Such an agenda will have to recognise insights gained from, in particular, the New Literacy Studies (Street, 1998, 2004) and the Academic Literacies movement (Lea & Street, 1998; Lillis & Scott, 2007), but it will also become enriched by a linguistic perspective (Biber, 2006; Blanton, 1994; Bachman & Palmer, 1996; Halliday, 1978, 1985, 1993, 1996, 2002; Hyland, 2009). In developing a template for the agenda we accordingly acknowledge the theoretical defensibility and the feasibility of different approaches to academic acculturation.Keywords: academic literacy development, academic discourse, academic  acculturation or integration, higher educatio

    Reading Ability and Academic Acculturation: The Case of South African Students entering Higher Education

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    First-year students experience a range of challenges when transferring from secondary to higher education (HE) (cf. Darlaston-Jones et al. 2003, Leki 2006, Brinkworth et al. 2009). This is no different in South Africa, where deviating levels of preparedness for the demands of HE is a recurring theme (Slonimsky and Shalem 2005, Van Schalkwyk 2008, Scott 2009, Yeld 2009, Van Dyk 2010, Van Dyk and Coetzee-Van Rooy 2012). Weideman (2003:56) rightfully points out that the inability to understand and utilise appropriate academic discourse has a detrimental effect on academic success. Young students need to acculturate to the academic environment while adopting the academic community’s currency (Van de Poel and Gasiorek 2012a:294). With this article, we wish to contribute to the discussion by reporting on the academic language ability of one group of first-year students at a South African university, with specific reference to these students’ reading ability, on the basis of the following data: (i) individual differences in terms of learner characteristics (race, first language, gender, Grade 12 results, academic performance); (ii) self-reported reading preparedness; and (iii) reading profiles resulting from a valid and reliable academic literacy test, the Test of Academic Literacy Levels (TALL) and its Afrikaans counterpart, the Toets van Akademiese Geletterdheidsvlakke (TAG). The findings suggest that academic reading ability, as reflected in the test results, is indeed one of the salient contributors to academic success (as confirmed in the literature), regardless of social and individual differences, and that it needs to be supported in order for students to perceive their reading ability in accordance with their reading performance and be able to progress in their academic acculturation. A follow-up study will report on students’ awareness-raising about their own academic reading through the use of the validated scale for Perceived Academic Reading Preparedness (PARP) as a pedagogical tool.Keywords: Academic Acculturation, Academic Literacy, Academic Reading, Perceptions of Reading Ability, Academic Performanc

    Detection Of DNA Damage By Use Of Escherichia Coli Carrying recA\u27::lux, uvrA\u27::lux, And alkA\u27::lux Reporter Plasmids

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    Plasmids were constructed in which DNA damage-inducible promoters recA, uvrA, and alkA from Escherichia coli were fused to the Vibrio fischeri luxCDABE operon. Introduction of these plasmids into E. coli allowed the detection of a dose-dependent response to DNA-damaging agents, such as mitomycin and UV irradiation. Bioluminescence was measured in real time over extended periods. The fusion of the recA promoter to luxCDABE showed the most dramatic and sensitive responses. lexA dependence of the bioluminescent SOS response was demonstrated, confirming that this biosensor\u27s reports were transmitted by the expected regulatory circuitry. Comparisons were made between luxCDABE and lacZ fusions to each promoter. It is suggested that the lux biosensors may have use in monitoring chemical, physical, and genotoxic agents as well as in further characterizing the mechanisms of DNA repair

    Oxidative Stress Detection With Escherichia Coli Harboring A katG\u27::lux Fusion

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    A plasmid containing a transcriptional fusion of the Escherichia coli katG promoter to a truncated Vibrio fischeri lux operon (luxCDABE) was constructed. An E. coli strain bearing this plasmid (strain DPD2511) exhibited low basal levels of luminescence, which increased up to 1,000-fold in the presence of hydrogen peroxide, organic peroxides, redox-cycling agents (methyl viologen and menadione), a hydrogen peroxide-producing enzyme system (xanthine and xanthine oxidase), and cigarette smoke. An oxyR deletion abolished hydrogen peroxide-dependent induction, confirming that oxyR controlled katG\u27::lux luminescence. Light emission was also induced by ethanol by an unexplained mechanism. A marked synergistic response was observed when cells were exposed to both ethanol and hydrogen peroxide; the level of luminescence measured in the presence of both inducers was much higher than the sum of the level of luminescence observed with ethanol and the level of luminescence observed with hydrogen peroxide. It is suggested that this construction or similar constructions may be used as a tool for assaying oxidant and antioxidant properties of chemicals, as a biosensor for environmental monitoring and as a tool for studying cellular responses to oxidative hazards

    Responses To Toxicants Of An Escherichia Coli Strain Carrying A uspA\u27::lux Genetic Fusion And An E. Coli Strain Carrying A grpE\u27::lux Fusion Are Similar

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    A transcriptional fusion of the Escherichia coli uspA promoter to luxCDABE was characterized and compared with a heat shock-responsive grpE\u27::lux fusion. Similarities in range and rank order of inducing conditions were observed; however, the magnitude of induction was typically greater for the grpE\u27::lux fusion strain

    Recent Type II Radio Supernovae

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    We present the results of radio observations, taken primarily with the Very Large Array, of Supernovae 1993J, 2001gd, 2001em, 2002hh, 2004dj, and 2004et. We have fit a parameterized model to the multi-frequency observations of each supernova. We compare the observed and derived radio properties of these supernovae by optical classification and discuss the implications.Comment: 5 pages, 2 figures, 1 table Conference Proceedings: "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCra

    Multi-Wavelength Properties of the Type IIb SN 2008ax

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    We present the UV, optical, X-ray, and radio properties of the Type IIb SN 2008ax discovered in NGC 4490. The observations in the UV are one of the earliest of a Type IIb supernova (SN). On approximately day four after the explosion, a dramatic upturn in the u and uvw1 (lambda_c = 2600 Angstroms) light curves occurred after an initial rapid decline which is attributed to adiabatic cooling after the initial shock breakout. This rapid decline and upturn is reminiscent of the Type IIb SN 1993J on day six after the explosion. Optical/near-IR spectra taken around the peak reveal prominent H-alpha, HeI, and CaII absorption lines. A fading X-ray source is also located at the position of SN 2008ax, implying an interaction of the SN shock with the surrounding circumstellar material and a mass-loss rate of the progenitor of M_dot = (9+/-3)x10^-6 solar masses per year. The unusual time evolution (14 days) of the 6 cm peak radio luminosity provides further evidence that the mass-loss rate is low. Combining the UV, optical, X-ray, and radio data with models of helium exploding stars implies the progenitor of SN 2008ax was an unmixed star in an interacting-binary. Modeling of the SN light curve suggests a kinetic energy (E_k) of 0.5x10^51 ergs, an ejecta mass (M_ej) of 2.9 solar masses, and a nickel mass (M_Ni) of 0.06 solar masses.Comment: Accepted to ApJ Letters, 14 pages, 3 figures, 2 table

    Improved distance determination to M51 from supernovae 2011dh and 2005cs

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    The appearance of two recent supernovae, SN 2011dh and 2005cs, both in M51, provides an opportunity to derive an improved distance to their host galaxy by combining the observations of both SNe. We apply the Expanding Photosphere Method to get the distance to M51 by fitting the data of these two SNe simultaneously. In order to correct for the effect of flux dilution, we use correction factors (zeta) appropriate for standard type II-P SNe atmospheres for 2005cs, but find zeta ~ 1 for the type IIb SN 2011dh, which may be due to the reduced H-content of its ejecta. The EPM analysis resulted in D_M51 = 8.4 +/- 0.7 Mpc. Based on this improved distance, we also re-analyze the HST observations of the proposed progenitor of SN 2011dh. We confirm that the object detected on the pre-explosion HST-images is unlikely to be a compact stellar cluster. In addition, its derived radius (~ 277$ R_sun) is too large for being the real (exploded) progenitor of SN 2011dh. The supernova-based distance, D = 8.4 Mpc, is in good agreement with other recent distance estimates to M51.Comment: 6 pages, 5 figures, accepted for publication in A&

    23 GHz VLBI Observations of SN 2008ax

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    We report on phase-referenced 23 GHz Very-Long-Baseline-Interferometry (VLBI) observations of the type IIb supernova SN 2008ax, made with the Very Long Baseline Array (VLBA) on 2 April 2008 (33 days after explosion). These observations resulted in a marginal detection of the supernova. The total flux density recovered from our VLBI image is 0.8±\pm0.3 mJy (one standard deviation). As it appears, the structure may be interpreted as either a core-jet or a double source. However, the supernova structure could be somewhat confused with a possible close by noise peak. In such a case, the recovered flux density would decrease to 0.48±\pm0.12 mJy, compatible with the flux densities measured with the VLA at epochs close in time to our VLBI observations. The lowest average expansion velocities derived from our observations are (1.90±0.30)×105(1.90 \pm 0.30) \times 10^5 km s1^{-1} (case of a double source) and (5.2±1.3)×104(5.2 \pm 1.3) \times 10^4 km s1^{-1} (taking the weaker source component as a spurious, close by, noise peak, which is the more likely interpretation). These velocities are 7.3 and 2 times higher, respectively, than the maximum ejecta velocity inferred from optical-line observations.Comment: 4 pages, 3 figures. Accepted in A&A on 24/03/200

    More Benefits of Semileptonic Rare B Decays at Low Recoil: CP Violation

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    We present a systematic analysis of the angular distribution of Bbar -> Kbar^\ast (-> Kbar pi) l^+ l^- decays with l = e, mu in the low recoil region (i.e. at high dilepton invariant masses of the order of the mass of the b-quark) to account model-independently for CP violation beyond the Standard Model, working to next-to-leading order QCD. From the employed heavy quark effective theory framework we identify the key CP observables with reduced hadronic uncertainties. Since some of the CP asymmetries are CP-odd they can be measured without B-flavour tagging. This is particularly beneficial for Bbar_s,B_s -> phi(-> K^+ K^-) l^+ l^- decays, which are not self-tagging, and we work out the corresponding time-integrated CP asymmetries. Presently available experimental constraints allow the proposed CP asymmetries to be sizeable, up to values of the order ~ 0.2, while the corresponding Standard Model values receive a strong parametric suppression at the level of O(10^-4). Furthermore, we work out the allowed ranges of the short-distance (Wilson) coefficients C_9,C_10 in the presence of CP violation beyond the Standard Model but no further Dirac structures. We find the Bbar_s -> mu^+ mu^- branching ratio to be below 9*10^-9 (at 95% CL). Possibilities to check the performance of the theoretical low recoil framework are pointed out.Comment: 18 pages, 3 fig.; 1 reference and comment on higher order effects added; EOS link fixed. Minor adjustments to Eqs 4.1-4.3 to match the (lower) q^2-cut as given in paper. Main results and conclusions unchanged; v3+v4: treatment of exp. uncert. in likelihood-function in EOS fixed and constraints from scan on C9,C10 updated (Fig 2,3 and Eqs 3.2,3.3). Main results and conclusions absolutely unchange
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