Localization-delocalization transition of a polaron near an impurity

We solve the problem of polaron localization on an attractive impurity by means of direct-space Diagrammatic Monte Carlo implemented for the system in the thermodynamic limit. In particular we determine the ground state phase diagram in dependence on the electron-phonon coupling and impurity potential strength for the whole phonon frequency range. Including the quantum phonon dynamics we find and characterize a new phase which is missing in the zero phonon-frequency limit (adiabatic approximation), where self-trapped polarons are not localized at shallow impurities. We predict and show that in the vicinity of the localization transition a region with a mixture of weak- and strong-coupling spectral response is realized.Comment: 4 pages, 4 figur

Drawing-writing culture: the truth-fiction spectrum of an ethno-graphic novel on the Sri Lankan civil war and migration

With our focus on an “ethno‐graphic novel” on the Sri Lankan civil war and the forcible displacement and migration of Tamil survivors, we make two main propositions while reflecting on the “graphic narrative turn” that has emerged in anthropology in recent years. First, we inscribe drawing into the “writing of cultures” where words have held a superior status in ethnographic representations. Rather than seeing drawings as perceptive tools for recording scenes in fieldwork alone, we extend them to a representational practice where they can have a deep, intricate, and equivalent entanglement with words to create synchronous affective intensities among a larger audience. Our second proposal follows Jean Rouch on cinéma vérité to interrogate assumptions about truth and fiction as portrayed by film representations. We propose a theory and practice for graphic novel production that we have termed vérités graphiques (literally, graphic realities). This describes the collaborative and interactive engagement with people's contributions and views, and their distillation and fictionalization through the ethno‐graphic form. We diverge from cinéma vérité, however, by highlighting a truth‐fiction spectrum that further challenges the presumed objectivity of what is seen, experienced, co‐created, and revealed

The effects of activating prior topic and metacognitive knowledge on text comprehension scores

Background Research on prior knowledge activation has consistently shown that activating learners' prior knowledge has beneficial effects on learning. If learners activate their prior knowledge, this activated knowledge serves as a framework for establishing relationships between the knowledge they already possess and new information provided to them. Thus far, prior knowledge activation has dealt primarily with topic knowledge in specific domains. Students, however, likely also possess at least some metacognitive knowledge useful in those domains, which, when activated, should aid in the deployment of helpful strategies during reading. Aims In this study, we investigated the effects of both prior topic knowledge activation (PTKA) and prior metacognitive knowledge activation (PMKA) on text comprehension scores. Samples & Methods Eighty-eight students in primary education were randomly distributed amongst the conditions of the 2 × 2 (PTKA yes/no × PMKA yes/no) designed experiment. Results Results show that activating prior metacognitive knowledge had a beneficial effect on text comprehension, whereas activating prior topic knowledge, after correcting for the amount of prior knowledge, did not. Conclusions Most studies deal with explicit instruction of metacognitive knowledge, but our results show that this may not be necessary, specifically in the case of students who already have some metacognitive knowledge. However, existing metacognitive knowledge needs to be activated in order for students to make better use of this knowledge

Teaching digital fiction: integrating experimental writing and current technologies

Today’s creative writers are immersed in a multiplicative, multimodal—digital—universe. It requires “multiliteracies”, all in a constantly and rapidly evolving technological environment, which are not yet fundamentally integrated into the basic literacy skills entrenched in school learning. How can creative writing instructors in higher education best prepare their students for the real-world contexts of their creative practice? One approach is to integrate the creative writing workshop with a focus on digital and interactive design. This paper outlines a module incorporating multiple literacies into a creative writing course, Playable Fiction, noting the affordances, limitations, and benefits of teaching workshops for writing digital fiction (“born-digital” fiction, composed for and read on digital devices). The researcher took an ethnographical approach to the question, designing a module to encourage creative writing students to experiment with digital fiction, and observing the effects on the students’ attitudes and their coursework. Included is a discussion of the benefits to students of developing multiliteracies and considerations for teaching, including issues of technical know-how and the lack of infrastructural support

Final elucidation of the absolute configuration of the signal metabolite hormaomycin

The complete absolute configuration of hormaomycin 1a has been established by HPLC and HPLC/MS experiments with appropriately derivatized 4-propylprolines, (2S,4S)-6 and (2R,4R)-6, as well as 4-(Z)-propenylprolines. cis-5 and trans-5, and also feeding experiments with enantiomerically pure samples of the deuterium-labeled 3-(2′-nitrocyclopropyl)alanine, (2S)-3,3-[D 2]15 and (2S)-2,2′-[D2]15, and 4-(Z)-propenylproline 2′,4-[D2]-(2S,4R)-5. The latter five amino acids were prepared for the first time and allowed one to unequivocally assign the hitherto unknown absolute configurations of the last four stereocenters in hormaomycin 1a. As a bonus, some new information about the biosynthesis of this molecule has also been gathered

From blog to bebo and beyond: Text, risk, participation

This paper broadly explores the notion that text is an artefact that encodes and displays the tensions, resistances, positioning and affinities of its producer and, further, that many of these drivers have their source in quite significant shifts in the broad contours of contemporary Western culture. Against this background, two different artefacts are analysed in this paper: a blog and a bebo page. The blog has been produced by an adult female academic and the bebo page by an early adolescent girl. These text producers and users are positioned quite differently in terms of geography, education, life experience, identity, social class and interests. They also have differential access to and experience of digital technologies. However, they both make use of the affordances of technologies, in particular Internet-connected laptops and desktops, to create and disseminate these texts to do ‘work’ on their behalf in particular social domains