Going beyond the linear approximation in describing electron- phonon coupling: relevance for the Holstein model

Using the momentum average approximation we study the importance of adding higher-than-linear terms in the electron-phonon coupling on the properties of single polarons described by a generalized Holstein model. For medium and strong linear coupling, even small quadratic electron-phonon coupling terms are found to lead to very significant quantitative changes in the properties of the polaron, which cannot be captured by a linear Holstein Hamiltonian with renormalized parameters. We argue that the bi-polaron phase diagram is equally sensitive to addition of quadratic coupling terms if the linear coupling is large. These results suggest that the linear approximation is likely to be inappropriate to model systems with strong electron-phonon coupling, at least for low carrier concentrations.Comment: 6 pages, 4 figures Final version accepted into EP

Digitization of the World: A Phenomenology of Digitization

The dissertation analyzes digitization through a phenomenological lens, understanding the digitization as an “outgrowth” of a potential that was always already latent within our being as the human-being. The analysis primarily utilizes the philosophic work of the 20th century philosophers, Martin Heidegger and Maurice Merleau-Ponty. Through their philosophies, I seek to synthesize Heidegger’s concept of de-severance with Merleau-Ponty’s concepts of embodiment and the world as possessing depth. In doing so, I bring these theoretical concepts together to build a phenomenological “picture” of how it is that the digitization of the world came into being. All the while, my ultimate project is seeking and displaying the underlying drive, or will, that occurs when human de-severance, our particular embodiment, and our unique access to the world as depth discover within the world the potential to digitize. This will, and the result of the interplay between human de-severance, embodiment, and the world’s depth is the-will-to-flatten. In putting forth this theory, I analyze how the will-to-flatten via digitization has influenced our understandings and engagement with embodiment, space, and intersubjectivity. While I argue that the will-to-flatten is the driving force of digitization, I ultimately seek to display that the telos of this will is a paradox that cannot be resolved

Crowdsourcing Formulaic Phrases: towards a new type of spoken corpus

Corpora have revolutionised the way we describe and analyse language in use. The sheer scale of collections of texts, along with the appropriate software for structuring and analysing this data, has led to a fuller understanding of the characteristics of language use in context. However, the development of corpora has been unbalanced. The assembly of collections of written texts is relatively straightforward, and as a result, the field has a number of very large corpora which focus on mainly written texts, although often with some spoken elements included, e.g. the COCA (520m words), GloWbE (1.9b), and the enTenTen (19b). In addition, a number of corpora now include samples of language used in social media and other web contexts alongside more traditional written and (transcribed) spoken language samples, e.g. the Open American National Corpus (planned corpus size 100m words, mirroring the British National Corpus). Conversely, the development of spoken corpora has lagged behind, mainly due to the time-consuming nature of recording and transcribing spoken content. Most of the spoken corpora that exist consist of material that is easily gathered by automated collection software, such as radio talk show and television news transcripts and other entertainment programming (e.g. the spoken elements of COCA). The nature of this spoken discourse is described as unscripted, however, it is certainly constrained, e.g. talk show radio has certain expectations about how the host will moderate the discussion. While the scripted/constrained oral content in these spoken corpora has proved informative in terns of the nature of spoken discourse (see Adolphs and Carter, 2013; Raso and Mello, 2014; Aijmer, 2002 and Carter and McCarthy, 1999 for notable studies), it is no substitute for spontaneous, unscripted oral discourse. Furthermore, even the automated collection of scripted/constrained spoken discourse has not yet enabled the development of large spoken corpora of a size comparable to the largest written corpora (e.g. the spoken component of the 100m British National Corpus is only 10m words with a further 10m words added in the new spoken BNC2014). The 10m word subcorpus of the BNC contains 4m words of spontaneous speech, and is controlled for a number of sociolinguistic and contextual variables. There are a number of smaller spoken corpora available, e.g. the Michigan Corpus of Academic Spoken English (MICASE) which at just under 2m words is both modest in size and quite specialised in content. This trend is reflected in other corpora of spoken discourse. Spontaneous spoken discourse forms a large part of everyday language use, and the development of larger and more representative corpora of spontaneous oral language is therefore desirable to inform linguistic description. The main constraint to this ambition has always been the time-consuming nature and financial cost related to the compilation of such corpora. Spoken corpora provide a unique resource for the exploration of how people interact in real-life communicative contexts. Depending on how spoken corpora are annotated (as discussed below), they present opportunities for examining patterns in, for example, spoken lexis and grammar, pragmatics, dialect and language variation. Spoken corpora are now used in a variety of different fields from translation to reference and grammar works, to studies of language change. The need for spontaneous unscripted corpora seems uncontroversial, however, compiling such corpora in the traditional way remains a formidable task. Advances have been made in other areas utilizing the power of people volunteering information about what they think and do. This approach is often referred to as crowdsourcing, and it holds the promise to both overcome some of the difficulties outlined above, and to add useful aspects to corpus compilation which traditional methods cannot offer.This paper thus explores a new approach to collecting samples of naturally occurring spoken language samples, which may allow researchers to take advantage of the burgeoning area of information crowdsourcing. Instead of relying on the typical recording and transcribing of spoken discourse, crowdsourcing may allow the collection of real-time data ‘in the wild’ by having participants report the language they hear around them. Specifically, we aim to investigate the level of precision and recall of the ‘crowd’ when it comes to reporting language they have heard in real certain contexts, alongside the use of a crowdsourcing toolkit to facilitate this task. This method of ‘reporting’ usage does come with its own issues of course, many of which have been highlighted in the literature on Discourse Completion Tasks (Schauer and Adolphs, 2006), and can merely be regarded as a proxy for usage. Investigating user memory in this context can therefore only be regarded as a first step in assessing the overall viability of the proposed approach to collecting language samples. As a focusing device for selection of reported language samples, we draw on the use of formulaic phrases, an area that have received considerable attention from different areas in applied linguistics

Evaluation der potenziellen Regeneratschädigung bei der Kallusumformung nach Distraktionsosteogenese der Mandibula: Eine experimentelle Untersuchung am Tiermodell

Zusammenfassung: Ziel: Bei der Korrektur dreidimensionaler Deformitäten des Gesichtsskelettes mit der Distraktionsosteogenese werden Umformungsvorgänge des Regenerates einerseits als Bestandteil des Behandlungsplans, andererseits im Falle eines Verlustes der Kontrolle über den Distraktionsvektor vorgenommen. Die vorliegende Untersuchung hatte das Ziel, die Grenzen der Kallusmanipulation zu beurteilen. Dazu wurden die Auswirkungen komprimierender sowie dehnender Einflüsse am gleichen Regenerat untersucht. Material und Methode: Bei 15Beagle-Hunden wurde mit speziell angefertigten bidirektionalen Distraktoren eine lineare Distraktion von 10mm beidseits im Unterkieferwinkel vorgenommen. Der neu gebildete Kallus wurde in einem Schritt um 20° anguliert, was im vorliegenden Modell einer Verkürzung/Verlängerung von ca. 35% der Ausgangslänge des Regenerates gleichkommt. Die Position des Rotationszentrums erlaubte es, das Regenerat gleichzeitig zu komprimieren und zu dehnen. Die Auswirkungen dieser mechanischen Einflüsse auf die Ossifikation des Regenerates wurden nach 6 bzw. 13Wochen beurteilt und mit einer Kontrollgruppe, bei der lediglich eine lineare Distraktion durchgeführt worden war, verglichen. Ergebnisse: Die radiologischen und histologischen Untersuchungen ergaben keinen statisch signifikanten Unterschied zwischen dem komprimierten und gedehnten Regenerat. Es zeigten sich jedoch im gedehnten Sektor des Kallus Zonen unvollständiger Ossifikation nach 6-wöchiger Konsolidierungszeit. Unter stabilen Verhältnissen wurde die verzögerte Knochenheilung im weiteren Verlauf kompensiert und eine vollständige Ossifikation nach 13Wochen erreicht. Schlussfolgerung: Unter stabilen Verhältnissen kann ein durch Distraktion gebildetes frisches Regenerat in einem beträchtlichen Ausmaß umgeformt werden, ohne die knöcherne Heilung bleibend zu kompromittieren. Die Dehnung des Kallus kann jedoch zu einer Verzögerung oder dem Ausbleiben des Ossifikationsprozesses führen und sollte vermieden werden. Dies lässt sich durch eine Überkorrektur der Regeneratlänge oder durch eine graduelle Angulation während des Distraktionsvorgangs erreiche

Assessment of mood in aphasia following stroke: validation of the Dynamic Visual Analogue Mood Scales (D-VAMS)

OBJECTIVES: To validate a non-verbal self-report measure of mood - the Dynamic Visual Analogue Mood Scales (D-VAMS) - against the Hospital Anxiety and Depression Scale (HADS) and assess its suitability as an outcome measure or screening measure for depressed mood following stroke. DESIGN: Cross-sectional observational cohort study. PARTICIPANTS: Forty-six stroke survivors (24% with aphasia) recruited from online, from stroke clubs and via an NHS rehabilitation service. METHODS: A set of seven bipolar scales was developed enabling users to report mood by modifying facial expression images using a slider. Participants completed a tablet/computer task, reporting their mood on these scales mixed randomly with versions which used only words. The HADS was then completed, followed by a repeat run of the two versions in a different, random sequence. RESULTS: Exploratory factor analysis identified one factor consistent with pleasantness of mood accounting for 80% of the variance. Internal consistency of D-VAMS was high ( α = 0.95), and there was a high correlation between face-only D-VAMS scores and HADS total scores ( r = -0.80, P < 0.001), as well as HADS-D/HADS-A subscale scores ( r = -0.73, P < 0.001; r = -0.71, P < 0.001). D-VAMS showed good sensitivity and specificity against HADS, with means of 85%/77% (sensitivity/specificity) against the HADS-D and 80%/77% against the HADS-A across nine cut-offs. CONCLUSION: D-VAMS is a valid and reliable measure likely suitable for assessment of depressed mood in aphasia following stroke. Though D-VAMS performed well as a screening measure in this study sample, further study is needed in the acute stage post-stroke

Subthalamic nucleus stimulation affects orbitofrontal cortex in facial emotion recognition: a pet study

Deep brain stimulation (DBS) of the bilateral subthalamic nucleus (STN) in Parkinson's disease is thought to produce adverse events such as emotional disorders, and in a recent study, we found fear recognition to be impaired as a result. These changes have been attributed to disturbance of the STN's limbic territory and would appear to confirm that the negative emotion recognition network passes through the STN. In addition, it is now widely acknowledged that damage to the orbitofrontal cortex (OFC), especially the right side, can result in impaired recognition of facial emotions (RFE). In this context, we hypothesized that this reduced recognition of fear is correlated with modifications in the cerebral glucose metabolism of the right OFC. The objective of the present study was first, to reinforce our previous results by demonstrating reduced fear recognition in our Parkinson's disease patient group following STN DBS and, second, to correlate these emotional performances with glucose metabolism using 18FDG-PET. The 18FDG-PET and RFE tasks were both performed by a cohort of 13 Parkinson's disease patients 3 months before and 3 months after surgery for STN DBS. As predicted, we observed a significant reduction in fear recognition following surgery and obtained a positive correlation between these neuropsychological results and changes in glucose metabolism, especially in the right OFC. These results confirm the role of the STN as a key basal ganglia structure in limbic circuits