625 research outputs found

    Are librarians teachers? Investigating academic librarians’ perceptions of their own teaching skills

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    Librarian roles in the education sector increasingly include teaching responsibilities, therefore librarians need to know more about teaching theory and techniques in order to provide high-quality information literacy (IL) teaching. There has been little published research into how librarians conceive of their teaching, their skills and themselves as teachers. This research, initially conducted for a Masters dissertation in the Information School at the University of Sheffield, investigates the variation in conceptions of their own teaching skills among academic librarians who teach IL in higher education (HE). It was investigated whether participants would describe themselves as teachers, whether they are influenced by teaching theories (and which ones), and whether they are actually teaching or training. Firstly the literature on pedagogy for IL, approaches to teaching IL in HE, and librarians as teachers, was reviewed before the research and its findings are discussed. A phenomenographic approach was used. A purposive sample of six librarians who teach IL in HE institutions in the north of England was chosen, selected to ensure maximum variation between participants and the resulting conceptions. Six interviews were conducted using phenomenographic techniques to encourage participants to talk about their conceptions, and the interviews were then transcribed and analysed. The data gives rise to four categories of description, each of which describes a conception that librarians hold of themselves and their teaching:: teacher-librarian; learning support; librarian who teaches; and trainer. The variation between categories is determined by interviewees’ conceptions of themselves, their teaching, IL, and other teachers. The results suggest that further support and training for librarians and library and information science (LIS) students would be beneficial and more in-depth and larger-scale research is recommended to test these conceptions and understand in greater detail the training experience and needs of librarians who teach. This article is based on a paper presented at LILAC 2015

    11-(2,2-Dimethylpropyl)-12-{2-[12-(2,2-dimethylpropyl)- 9,10-dihydro-9,10-ethenoanthracen-11-yl]- ethyl}-9,10-dihydro-9,10-ethenoanthracene

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    Reaction of tert-butyllithium with 11,12-dimethylene-9,10- dihydro-9,10-ethanoanthracene and 4,5-diiodopentacyclo- [4.3.0.02,4.03,8.05,7]nonane gives three products, one of which crystallizes from petroleum ether as the title compound, C44H46, (I). Molecules of (I) are positioned on inversion centers (Z0 = 0.5) in the space group P21/n and lack any discernible intermolecular interactions

    11-(2,2-Dimethylpropyl)-12-{2-[12-(2,2-dimethylpropyl)- 9,10-dihydro-9,10-ethenoanthracen-11-yl]- ethyl}-9,10-dihydro-9,10-ethenoanthracene

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    Reaction of tert-butyllithium with 11,12-dimethylene-9,10- dihydro-9,10-ethanoanthracene and 4,5-diiodopentacyclo- [4.3.0.02,4.03,8.05,7]nonane gives three products, one of which crystallizes from petroleum ether as the title compound, C44H46, (I). Molecules of (I) are positioned on inversion centers (Z0 = 0.5) in the space group P21/n and lack any discernible intermolecular interactions

    Randomized multicentre pilot study of sacubitril/valsartan versus irbesartan in patients with chronic kidney disease: United Kingdom Heart and Renal Protection (HARP)- III—rationale, trial design and baseline data

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    BACKGROUND: Patients with chronic kidney disease (CKD) are at risk of progression to end-stage renal disease and cardiovascular disease. Data from other populations and animal experiments suggest that neprilysin inhibition (which augments the natriuretic peptide system) may reduce these risks, but clinical trials among patients with CKD are required to test this hypothesis. METHODS: UK Heart and Renal Protection III (HARP-III) is a multicentre, double-blind, randomized controlled trial comparing sacubitril/valsartan 97/103 mg two times daily (an angiotensin receptor-neprilysin inhibitor) with irbesartan 300 mg one time daily among 414 patients with CKD. Patients ≥18 years of age with an estimated glomerular filtration rate (eGFR) of ≥45 but <60 mL/min/1.73 m2 and urine albumin:creatinine ratio (uACR) >20 mg/mmol or eGFR ≥20 but <45 mL/min/1.73 m2 (regardless of uACR) were invited to be screened. Following a 4- to 7-week pre-randomization single-blind placebo run-in phase (during which any current renin-angiotensin system inhibitors were stopped), willing and eligible participants were randomly assigned either sacubitril/valsartan or irbesartan and followed-up for 12 months. The primary aim was to compare the effects of sacubitril/valsartan and irbesartan on measured GFR after 12 months of therapy. Important secondary outcomes include effects on albuminuria, change in eGFR over time and the safety and tolerability of sacubitril/valsartan in CKD. RESULTS: Between November 2014 and January 2016, 620 patients attended a screening visit and 566 (91%) entered the pre-randomization run-in phase. Of these, 414 (73%) participants were randomized (mean age 63 years; 72% male). The mean eGFR was 34.0 mL/min/1.73 m2 and the median uACR was 58.5 mg/mmol. CONCLUSIONS: UK HARP-III will provide important information on the short-term effects of sacubitril/valsartan on renal function, tolerability and safety among patients with CKD

    Nebular Spectra and Explosion Asymmetry of Type Ia Supernovae

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    The spectral signatures of asymmetry in Type Ia Supernova (SN Ia) explosions are investigated, using a sample of late-time nebular spectra. First, a kinematical model is constructed for SN Ia 2003hv, which can account for the main features in its optical, Near-Infrared (NIR), and Mid-Infrared (Mid-IR) late-time spectra. It is found that an asymmetric off-center model can explain the observed characteristics of SN 2003hv. This model includes a relatively high density, Fe-rich region which displays a large velocity off-set, and a relatively low density, extended 56Ni-rich region which is more spherically distributed. The high density region consists of the inner stable Fe-Ni region and outer 56Ni-rich region. Such a distribution may be the result of a delayed-detonation explosion, in which the first deflagration produces the global asymmetry in the innermost ejecta, while the subsequent detonation can lead to the bulk spherical symmetry. This configuration, if viewed from the direction of the off-set, can consistently explain the blueshift in some of the emission lines and virtually no observed shift in other lines in SN 2003hv. For this model, we then explore the effects of different viewing angles and the implications for SNe Ia in general. The model predicts that a variation of the central wavelength, depending on the viewing angle, should be seen in some lines (e.g., [Ni II]7378), while the strongest lines (e.g., [Fe III] blend at 4700A) will not show this effect. By examining optical nebular spectra of 12 SNe Ia, we have found that such a variation indeed exists. We suggest that the global asymmetry in the innermost ejecta, as likely imprint of the deflagration flame propagation, is a generic feature of SNe Ia (abridged).Comment: 14 pages, 11 figures, 4 tables. Accepted for publication in the Astrophysical Journal. Minor correction

    Two-loop corrections to the decay rate of parapositronium

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    Order α2\alpha^2 corrections to the decay rate of parapositronium are calculated. A QED scattering calculation of the amplitude for electron-positron annihilation into two photons at threshold is combined with the technique of effective field theory to determine an NRQED Hamiltonian, which is then used in a bound state calculation to determine the decay rate. Our result for the two-loop correction is 5.1243(33)5.1243(33) in units of (α/π)2(\alpha/\pi)^2 times the lowest order rate. This is consistent with but more precise than the result 5.1(3)5.1(3) of a previous calculation.Comment: 26 pages, 7 figure

    The Spectrum of Electromagnetic Jets from Kerr Black Holes and Naked Singularities in the Teukolsky Perturbation Theory

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    We give a new theoretical basis for examination of the presence of the Kerr black hole (KBH) or the Kerr naked singularity (KNS) in the central engine of different astrophysical objects around which astrophysical jets are typically formed: X-ray binary systems, gamma ray bursts (GRBs), active galactic nuclei (AGN), etc. Our method is based on the study of the exact solutions of the Teukolsky master equation for electromagnetic perturbations of the Kerr metric. By imposing original boundary conditions on the solutions so that they describe a collimated electromagnetic outflow, we obtain the spectra of possible {\em primary jets} of radiation, introduced here for the first time. The theoretical spectra of primary electromagnetic jets are calculated numerically. Our main result is a detailed description of the qualitative change of the behavior of primary electromagnetic jet frequencies under the transition from the KBH to the KNS, considered here as a bifurcation of the Kerr metric. We show that quite surprisingly the novel spectra describe linearly stable primary electromagnetic jets from both the KBH and the KNS. Numerical investigation of the dependence of these primary jet spectra on the rotation of the Kerr metric is presented and discussed.Comment: 18 pages, 35 figures, LaTeX file. Final version. Accepted for publication in Astrophysics and Space Science. Amendments. Typos corrected. Novel notion -"primary jet" is introduced. New references and comments adde

    Classification of Supernovae

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    The current classification scheme for supernovae is presented. The main observational features of the supernova types are described and the physical implications briefly addressed. Differences between the homogeneous thermonuclear type Ia and similarities among the heterogeneous core collapse type Ib, Ic and II are highlighted. Transforming type IIb, narrow line type IIn, supernovae associated with GRBs and few peculiar objects are also discussed.Comment: 16 Pages, 4 figures, to be published in "Supernovae and Gamma-Ray Bursters," ed. Kurt W. Weile

    Multimessenger astronomy with the Einstein Telescope

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    Gravitational waves (GWs) are expected to play a crucial role in the development of multimessenger astrophysics. The combination of GW observations with other astrophysical triggers, such as from gamma-ray and X-ray satellites, optical/radio telescopes, and neutrino detectors allows us to decipher science that would otherwise be inaccessible. In this paper, we provide a broad review from the multimessenger perspective of the science reach offered by the third generation interferometric GW detectors and by the Einstein Telescope (ET) in particular. We focus on cosmic transients, and base our estimates on the results obtained by ET's predecessors GEO, LIGO, and Virgo.Comment: 26 pages. 3 figures. Special issue of GRG on the Einstein Telescope. Minor corrections include

    Gravitational radiation from gamma-ray bursts as observational opportunities for LIGO and VIRGO

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    Gamma-ray bursts are believed to originate in core-collapse of massive stars. This produces an active nucleus containing a rapidly rotating Kerr black hole surrounded by a uniformly magnetized torus represented by two counter-oriented current rings. We quantify black hole spin-interactions with the torus and charged particles along open magnetic flux-tubes subtended by the event horizon. A major output of Egw=4e53 erg is radiated in gravitational waves of frequency fgw=500 Hz by a quadrupole mass-moment in the torus. Consistent with GRB-SNe, we find (i) Ts=90s (tens of s, Kouveliotou et al. 1993), (ii) aspherical SNe of kinetic energy Esn=2e51 erg (2e51 erg in SN1998bw, Hoeflich et al. 1999) and (iii) GRB-energies Egamma=2e50 erg (3e50erg in Frail et al. 2001). GRB-SNe occur perhaps about once a year within D=100Mpc. Correlating LIGO/Virgo detectors enables searches for nearby events and their spectral closure density 6e-9 around 250Hz in the stochastic background radiation in gravitational waves. At current sensitivity, LIGO-Hanford may place an upper bound around 150MSolar in GRB030329. Detection of Egw thus provides a method for identifying Kerr black holes by calorimetry.Comment: to appear in PRD, 49
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