Falling liquid films with blowing and suction

Flow of a thin viscous film down a flat inclined plane becomes unstable to long wave interfacial fluctuations when the Reynolds number based on the mean film thickness becomes larger than a critical value (this value decreases as the angle of inclination with the horizontal increases, and in particular becomes zero when the plate is vertical). Control of these interfacial instabilities is relevant to a wide range of industrial applications including coating processes and heat or mass transfer systems. This study considers the effect of blowing and suction through the substrate in order to construct from first principles physically realistic models that can be used for detailed passive and active control studies of direct relevance to possible experiments. Two different long-wave, thin-film equations are derived to describe this system; these include the imposed blowing/suction as well as inertia, surface tension, gravity and viscosity. The case of spatially periodic blowing and suction is considered in detail and the bifurcation structure of forced steady states is explored numerically to predict that steady states cease to exist for sufficiently large suction speeds since the film locally thins to zero thickness giving way to dry patches on the substrate. The linear stability of the resulting nonuniform steady states is investigated for perturbations of arbitrary wavelengths, and any instabilities are followed into the fully nonlinear regime using time-dependent computations. The case of small amplitude blowing/suction is studied analytically both for steady states and their stability. Finally, the transition between travelling waves and non-uniform steady states is explored as the suction amplitude increases

Didymus the Blind on 1 Corinthians 15

This thesis presents fourth century Alexandrian theologian and biblical commentator, Didymus the Blind (ca. 313-398), to English-language readers through a translation and study of his writing on 1 Corinthians 15. (This writing constitutes the bulk of what survives of Didymus’ 1 Corinthians commentary; some remarks on chapter 16 are also extant.) The translation represents the first appearance in English of any of Didymus’ works. After a brief introduction to Didymus, the translation of his 1 Corinthians 15 commentary is given in full. Then this text is studied by sections each following the format of (1) Greek text (copied from Karl Staab’s 1934 edition), (2) translation, and (3) analysis. The analysis attempts to make intelligible Didymus’ statements most often by showing how they are responses to beliefs, opinions, or concerns arising for Didymus from the Pauline text. An annotated bibliography of Didymus’ works and of works on Didymus follows. An index of all words of the Greek text, giving the page and line numbers of their occurrence in the Staab edition is appended

Arc Phenomena in low-voltage current limiting circuit breakers

Circuit breakers are an important safety feature in most electrical circuits, and they act to prevent excessive currents caused by short circuits, for example. Low-voltage current limiting circuit breakers are activated by a trip solenoid when a critical current is exceeded. The solenoid moves two contacts apart to break the circuit. However, as soon as the contacts are separated an electric arc forms between them, ionising the air in the gap, increasing the electrical conductivity of air to that of the hot plasma that forms, and current continues to flow. The currents involved may be as large as 80,000 amperes. Critical to the success of the circuit breaker is that it is designed to cause the arc to move away from the contacts, into a widening wedge-shaped region. This lengthens the arc, and then moves it onto a series of separator plates called an arc divider or splitter. The arc divider raises the voltage required to sustain the arcs across it, above the voltage that is provided across the breaker, so that the circuit is broken and the arcing dies away. This entire process occurs in milliseconds, and is usually associated with a sound like an explosion and a bright ash from the arc. Parts of the contacts and the arc divider may melt and/or vapourise. The question to be addressed by the Study Group was to mathematically model the arc motion and extinction, with the overall aim of an improved understanding that would help the design of a better circuit breaker. Further discussion indicated that two key mechanisms are believed to contribute to the movement of the arc away from the contacts, one being self-magnetism (where the magnetic field associated with the arc and surrounding circuitry acts to push it towards the arc divider), and the other being air flow (where expansion of air combined with the design of the chamber enclosing the arc causes gas flow towards the arc divider). Further discussion also indicated that a key aspect of circuit breaker design was that it is desirable to have as fast a quenching of the arc as possible, that is, the faster the circuit breaker can act to stop current flow, the better. The relative importance of magnetic and air pressure effects on quenching speed is of central interest to circuit design

The Right Stuff: Inquiry Training, Teaching & Transfer for Content Mastery in the Sciences

The standardized testing movement has inadvertently placed pressure on elementary and secondary instructors to teach to the test. Primarily this is manifested through memorization and testing skills training and less on developing content mastery and problem solving. Hands-on activities (also referred to as inquiry learning) are lauded by the literature as an effective methodology in the development of content mastery (Akerson, V., Hanson, D., & Cullen, T.; NSF, 2010; Smith, T., Desimone, L., Zeidner, T., Dunn, A., Bhatt, M. & Rumyantseva, N., 2007). Nevertheless, administrators often see the inquiry method as an ineffective use of classroom and training time diverting attention away from test preparation. The research abounds, however, regarding the positive influence hands-on/ inquiry-based learning can have on testing results (Cuevas, P., Lee, O., Hart, J. & Deaktor, R., 2005; Marx, R., Blumenfeld, P. C., Krajcik, J., Fishman, B., Solomay, E., Geier, R. & Tal, R. T., 2004; Stohr- Hunt, P. M., 1996; Ruby, A., 2006; and Ashman, S., 2007)

High magnetic field pulsars and magnetars: a unified picture

We propose a unified picture of high magnetic field radio pulsars and magnetars by arguing that they are all rotating high-field neutron stars, but have different orientations of their magnetic axes with respective to their rotation axes. In strong magnetic fields where photon splitting suppresses pair creation near the surface, the high-field pulsars can have active inner accelerators while the anomalous X-ray pulsars cannot. This can account for the very different observed emission characteristics of the anomalous X-ray pulsar 1E 2259+586 and the high field radio pulsar PSR J1814-1744. A predicted consequence of this picture is that radio pulsars having surface magnetic field greater than about $2\times 10^{14}$ G should not exist.Comment: 5 pages, emulateapj style, accepted for publication in the ApJ Letter

A5: Grafton Notch State Park: Glacial Gorges and Streams Under Pressure in the Mahoosic Range, Maine

Guidebook for field trips in Western Maine and Northern New Hampshire: New England Intercollegiate Geological Conference, p. 95-104

Prácticas de exclusión en culturas escolares inclusivas en Reino Unido

A tension has emerged in the United Kingdom over the last 30 years between policies designed to achieve educational excellence and policies seeking to achieve inclusive practice. The introduction of devolution across the jurisdictions of the United Kingdom has led to differences in practices developed from what were originally a common set of cultural and historical values and beliefs. Policy changes in England in particular have resulted in perverse incentives for schools to not meet the needs of students with Special Educational Needs and Disabilities and which can result in their exclusion from school. We illustrate the working of perverse incentives through a cultural historical analysis of the ways that professionals from different services may have different object motives. We argue for practices of inter-professional co-configuration and knotworking in order to meaningful relations and patterns of communication that join services around young people with Special Educational Needs and Disabilities.En los últimos 30 años ha surgido una tensión en Reino Unido entre las políticas diseñadas para alcanzar la excelencia educativa y las políticas que buscan promover una práctica inclusiva. La descentralización y consiguiente traspaso de competencias a las cuatro jurisdicciones de Reino Unido ha llevado a diferencias en las prácticas desarrolladas a partir de lo que originalmente era un conjunto común de valores y creencias culturales e históricas. En particular los cambios de política en Inglaterra han resultado en incentivos perversos para que las escuelas no satisfagan las necesidades de los estudiantes con necesidades educativas especiales y discapacidades y pueden terminar en su exclusión escolar. Ilustramos el funcionamiento de estos incentivos perversos a través de un análisis histórico cultural de las formas en que los profesionales de diferentes servicios pueden tener diferentes motivos de objeto. Abogamos por prácticas de co-configuración interprofesional y el trabajo en nudos con el fin de lograr relaciones y patrones de comunicación significativos que unan a los servicios para jóvenes con discapacidades y necesidades educativas especiales

The role of the right hemisphere in semantic control: A case-series comparison of right and left hemisphere stroke.

Semantic control processes guide conceptual retrieval so that we are able to focus on non-dominant associations and features when these are required for the task or context, yet the neural basis of semantic control is not fully understood. Neuroimaging studies have emphasised the role of left inferior frontal gyrus (IFG) in controlled retrieval, while neuropsychological investigations of semantic control deficits have almost exclusively focussed on patients with left-sided damage (e.g., patients with semantic aphasia, SA). Nevertheless, activation in fMRI during demanding semantic tasks typically extends to right IFG. To investigate the role of the right hemisphere (RH) in semantic control, we compared nine RH stroke patients with 21 left-hemisphere SA patients, 11 mild SA cases and 12 healthy, aged-matched controls on semantic and executive tasks, plus experimental tasks that manipulated semantic control in paradigms particularly sensitive to RH damage. RH patients had executive deficits to parallel SA patients but they performed well on standard semantic tests. Nevertheless, multimodal semantic control deficits were found in experimental tasks involving facial emotions and the 'summation' of meaning across multiple items. On these tasks, RH patients showed effects similar to those in SA cases - multimodal deficits that were sensitive to distractor strength and cues and miscues, plus increasingly poor performance in cyclical matching tasks which repeatedly probed the same set of concepts. Thus, despite striking differences in single-item comprehension, evidence presented here suggests semantic control is bilateral, and disruption of this component of semantic cognition can be seen following damage to either hemisphere