About the Dirac Equation with a δ\delta potential

An elementary treatment of the Dirac Equation in the presence of a three-dimensional spherically symmetric $\delta (r-r_0)$-potential is presented. We show how to handle the matching conditions in the configuration space, and discuss the occurrence of supercritical effects.Comment: 8 pages, 1 postscript figure, Latex, Revise

Exit times in non-Markovian drifting continuous-time random walk processes

By appealing to renewal theory we determine the equations that the mean exit time of a continuous-time random walk with drift satisfies both when the present coincides with a jump instant or when it does not. Particular attention is paid to the corrections ensuing from the non-Markovian nature of the process. We show that when drift and jumps have the same sign the relevant integral equations can be solved in closed form. The case when holding times have the classical Erlang distribution is considered in detail.Comment: 9 pages, 3 color plots, two-column revtex 4; new Appendix and references adde

Using principles of authentic assessment to redesign written examinations and tests

Tests and examinations are widely used internationally. Despite their pervasiveness, they tend to measure lower order thinking skills in a decontextualized manner at a time when the literature frequently argues for the benefits of a richer, authentic approach to assessment. The focus of this paper is to improve authenticity in test assessment methods through promoting realism, cognitive challenge and evaluative judgement during the planning, administering and following up of assessment tasks. The article builds on a systematic literature review, in which the main principles of authentic assessment were outlined. In this paper, we posit how these principles can be implemented through the three chronological phases of the assessment process: before, during and after the act of assessment

Dissection, in vivo imaging and analysis of the mouse epitrochleoanconeus muscle

Analysis of rodent muscles affords an opportunity to glean key insights into neuromuscular development and the detrimental impact of disease-causing genetic mutations. Muscles of the distal leg, for instance the gastrocnemius and tibialis anterior, are commonly used in such studies with mice and rats. However, thin and flat muscles, which can be dissected, processed and imaged without major disruption to muscle fibres and nerve-muscle contacts, are more suitable for accurate and detailed analyses of the peripheral motor nervous system. One such wholemount muscle is the predominantly fast twitch epitrochleoanconeus (ETA), which is located in the upper forelimb, innervated by the radial nerve, and contains relatively large and uniformly flat neuromuscular junctions (NMJs). To facilitate incorporation of the ETA into the experimental toolkit of the neuromuscular disease field, here, we describe a simple method for its rapid isolation (<5 min), supported by high-resolution videos and step-by-step images. Furthermore, we outline how the ETA can be imaged in live, anaesthetised mice, to enable examination of dynamic cellular processes occurring at the NMJ and within intramuscular axons, including transport of organelles, such as mitochondria and signalling endosomes. Finally, we present reference data on wild-type ETA fibre-type composition in young adult, male C57BL6/J mice. Comparative neuroanatomical studies of different muscles in rodent models of disease can generate critical insights into pathogenesis and pathology; dissection of the wholemount ETA provides the possibility to diversify the repertoire of muscles analysed for this endeavour

Expanding the Toolkit for In Vivo Imaging of Axonal Transport

Axonal transport maintains neuronal homeostasis by enabling the bidirectional trafficking of diverse organelles and cargoes. Disruptions in axonal transport have devastating consequences for individual neurons and their networks, and contribute to a plethora of neurological disorders. As many of these conditions involve both cell autonomous and non-autonomous mechanisms, and often display a spectrum of pathology across neuronal subtypes, methods to accurately identify and analyze neuronal subsets are imperative. This paper details protocols to assess in vivo axonal transport of signaling endosomes and mitochondria in sciatic nerves of anesthetized mice. Stepwise instructions are provided to 1) distinguish motor from sensory neurons in vivo, in situ, and ex vivo by using mice that selectively express fluorescent proteins within cholinergic motor neurons; and 2) separately or concurrently assess in vivo axonal transport of signaling endosomes and mitochondria. These complementary intravital approaches facilitate the simultaneous imaging of different cargoes in distinct peripheral nerve axons to quantitatively monitor axonal transport in health and disease

Conocimiento y actitud del odontólogo frente al manejo del tabaquismo: estudio comparativo entre España, Italia y Venezuela

espanolIntroduccion: El Odontologo es capaz de ejercer un gran impacto en el tabaquismo a traves de su contacto con los pacientes y la deteccion precoz de lesiones bucales. El objetivo de este estudio fue determinar el conocimiento y la actitud de los odontologos frente al tabaquismo en tres paises distintos. Materiales y metodos: Se realizo una encuesta a 293 odontologos, 93 de ellos localizados en Caracas (OV), 90 con practica odontologica en Madrid (OE) y 110 en Milan (OI). Resultados: 46 OE y 22 OI indicaron ser fumadores, mientras que tan solo 10 OV admitieron ser fumadores. 80 (86,02%) OV, 66 (73,33%) OE y todos los OI refirieron registrar en la historia datos relacionados con tabaquismo en la primera consulta del paciente. La mayoria motiva a sus pacientes a dejar de fumar, sin embargo, 72,04% (67) OV, 55,55% (50) OE y 100% OI no recomiendan ninguna terapia de apoyo. Solo 7 odontologos (2,38%) (2 OV y 5 OE) reconocieron el medicamento Bupropion pero ningun odontologo lo ha indicado. Finalmente, 137 odontologos han diagnosticado cancer bucal, de los cuales 108 eran OI. Conclusiones: Los odontologos, independientemente del pais, tienen actitudes positivas para participar en el control del tabaquismo, pero no manejan la informacion relacionada ni ejercen un rol activo en la cesacion. Probablemente esta situacion se deba a la falta de entrenamiento durante sus estudios de pre y/o postgrado lo cual amerita una revision de los planes curriculares de Odontologia a nivel mundial. EnglishIntroduction: Health care professionals have an important role in tobacco control. Dentists are capable of having a great impact in smoking cessation due to their regular contact with patients and the rapid detection of oral signs produced by smoking. Unfortunately, there are few dentists actively involved in smoking control. The aim of this study was to investigate various aspects of dentists' beliefs and practices with respect to smoking cessation. Materials & Methods: A questionnaire about smoking cessation was filled in person by 293 dentists. 93 dentists were from Caracas-Venezuela (VD), 90 were from Madrid-Spain (SD) and 110 from Milan-Italy (ID). Results: 46 SD and 22 ID were smokers. Only 10 VD admitted to smoke. 80 (86.02%) VD, 66 (73.33%) SD and 100% of ID said that they recorded smoking status during the first consultation. However, none routinely update their records on smoking status. The majority of respondents encourage their patients to stop smoking, though, 72.04% (67) VD, 55.55% (50) SD and 100% ID do not recommend or prescribe any cessation therapy. Just 7 (2.38%) of all dentists had heard about the use of Bupropion, however, they had never indicated. Finally, 137 dentists (108 ID) have diagnosed oral cancer in their patients. Conclusions: Dentists have positive attitudes to being involved in smoking cessation interventions, but they do not manage all the information related to it. It is probably due to a lack of training or education during their undergraduate and postgraduate studies. Further studies should evaluate inclusion of smoking cessation instruction in Venezuelan, Spanish and Italian dentistry curriculum

Cutting through Content Clutter: How Speech and Image Acts Drive Consumer Sharing of Social Media Brand Messages

Consumer-to-consumer brand message sharing is pivotal for effective social media marketing. Even as companies join social media conversations and generate millions of brand messages, it remains unclear what, how, and when brand messages stand out and prompt sharing by consumers. With a conceptual extension of speech act theory, this study offers a granular assessment of brands’ message intentions (i.e., assertive, expressive, or directive) and the effects on consumer sharing. A text mining study of more than two years of Facebook posts and Twitter tweets by well-known consumer brands empirically demonstrates the impacts of distinct message intentions on consumers’ message sharing. Specifically, the use of rhetorical styles (alliteration and repetitions) and cross-message compositions enhance consumer message sharing. As a further extension, an image-based study demonstrates that the presence of visuals, or so-called image acts, increases the ability to account for message sharing. The findings explicate brand message sharing by consumers and thus offer guidance to content managers for developing more effective conversational strategies in social media marketing