5,388 research outputs found
Harkness learning: principles of a radical American pedagogy
This paper investigates and argues for Harkness learning: an approach to education that inculcates a culture of enquiry, driven by students in dialogue around a table. Tracing the history of the Harkness reforms in education at Phillips Exeter Academy, their pedagogical and philosophical roots are considered. Although partly inspired by the Oxford tutorial system and the Socratic concept of dialogue, Harkness departs from there to a radical classroom dynamic. The teacher is required to be more open-minded and less controlling over outcomes, to take the risk of listening more and saying less. This shift in emphasis fits with a distinctly American philosophical respect for the sanctity of the free thought and originality of the individual, which here is traced to Transcendentalist ideals that have permeated American culture. It can also be compared with Problem-Based Learning and there are certain significant overlaps between these pedagogies. However, Harkness is sometimes narrowly misunderstood as a technique for teaching, which takes the approach out of context. It needs to be understood in the broad frame of cultural reform of an institution – it is a useful symbol for a community committed to student discourse and problem solving. In this respect, Harkness owes a further debt to pragmatism – another great American philosophical-educational tradition
Viscous Boundary Value Problems for Symmetric Systems with Variable Multiplicities
Extending investigations of M\'etivier&Zumbrun in the hyperbolic case, we
treat stability of viscous shock and boundary layers for viscous perturbations
of multidimensional hyperbolic systems with characteristics of variable
multiplicity, specifically the construction of symmetrizers in the
low-frequency regime where variable multiplicity plays a role. At the same
time, we extend the boundary-layer theory to ``real'' or partially parabolic
viscosities, Neumann or mixed-type parabolic boundary conditions, and systems
with nonconservative form, in addition proving a more fundamental version of
the Zumbrun--Serre--Rousset theorem, valid for variable multiplicities,
characterizing the limiting hyperbolic system and boundary conditions as a
nonsingular limit of a reduced viscous system. The new effects of viscosity are
seen to be surprisingly subtle; in particular, viscous coupling of crossing
hyperbolic modes may induce a destabilizing effect. We illustrate the theory
with applications to magnetohydrodynamics
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The impacts of climate change on Greek airports
Time series of meteorological parameters at ten Greek airports since 1955 indicated the level of
climate change in the Eastern Mediterranean area. Using this data, take-off performance was
analysed for the DHC-8-400—a typical short range turboprop airliner, and the A320, a typical
medium scale turbofan airliner. For airports with longer runways, a steady but unimportant
increase in take-off distances was found. For airports with shorter runways, the results indicate a
steady reduction in available payload. At the most extreme case, results show that for an Airbus
A320, operating from the, relatively short, 1511m runway at Chios Airport, the required
reduction in payload would be equivalent to 38 passengers with their luggage, or fuel for 700
nautical miles (1300 km) per flight, for the period between the A320’s entry to service in 1988
and 2017. These results indicate that for airports where aeroplane maximum take-off mass is a
performance limited function of runway length, and where minimum temperatures have
increased and/or mean headwind components decreased, climate change has already had a
marked impact on the economic activity in the airline industry. Similar analyses could be
usefully carried out for other runway-length–limited airports, which may often include island
airports. It is also noted that previous research has only considered temperature effects, and not
wind effects. Wind effects in this study are less significant than temperature, but nonetheless
have an effect on both field performance noise and pollution nuisance around airports
The dependence of ionic mobility on the viscosity of the medium
Thesis (PhD)--University of Illinois, 1913TypescriptVit
Compound 49b: A Novel Beta-Adrenergic Receptor Agonist in the Treatment of Diabetic Retinopathy
Diabetic retinopathy is the leading cause of blindness in working Americans. While there are therapeutic regimens for the disease, more effective methods are needed. We have previously shown that a non-specific beta-adrenergic receptor agonist, isoproterenol, was effective in preventing functional and morphological changes associated with diabetic retinopathy in the rat. Isoproterenol also produced left ventricle remodeling suggesting it entered the systemic circulation. We therefore synthesized various novel beta-adrenergic receptor compounds and screened these compounds in vitro for their ability to reduce markers of inflammation and apoptosis. Of the various compounds tested, Compound 49b was able to reduce both inflammation and apoptosis in vitro in both retinal endothelial cells (REC) and Müller cells and did so at a significantly lower concentration than isoproterenol, deeming it the most effective compound.
Objective. We evaluated the effectiveness of Compound 49b to prevent and delay changes associated with diabetic retinopathy without systemic effects. We hypothesized that topical application of Compound 49b could prevent and delay the onset of functional and morphological markers of diabetic retinopathy and restore retinal cellular signaling, without affecting the heart.
Methods. Male rats were made diabetic with a streptozotocin injection (60mg/kg). Two days after the injection, glucose measurements were obtained. Two groups of rats were used for these two separate studies. In the prevention studies, a subset of the diabetic rats were started on daily 1mM Compound 49b eye drops for either 2-months or 8-months upon the verification of diabetes, while the control and diabetic only subgroups received no treatment. In the delayed treated studies, animals were placed on Compound 49b after 6-months of untreated diabetes. Once optimal dose and time course was obtained, body weight, blood glucose, intraocular pressure, blood pressure, and electrical activity of the retina were measured monthly over the duration of the prevention and delayed treatment studies. Insulin signaling, tumor necrosis factor!alpha (TNF-!) levels, and cleavage of caspase 3 were analyzed after 2- and 8-months or 2- and 6-months of treatment.
Results. Protein levels of TNF-! and cleaved caspase 3 were increased in the retinas of diabetic rats, but were returned to normal values following 1mM Compound 49b treatment. Since we have previously found that topical isoproterenol produced left ventricular remodeling, we wanted to investigate whether Compound 49b could overcome this obstacle. Left ventricular samples from diabetes+Compound 49b-treated rats were not significantly different than diabetes alone rats after statistical analyses.
Conclusion. Data showed that daily topical 1mM Compound 49b eye drops reduced TNF-! levels and cleaved caspase 3 levels, while maintaining insulin receptor signal transduction in the diabetic retina. Additionally, Compound 49b maintained retinal electrical activity, as measured by electroretinogram (ERG) analysis. Data indicates that Compound 49b does not reach the systemic circulation or alter blood pressure or intraocular pressure, suggesting that it may represent a novel treatment option for diabetic retinopathy
A Sea - Grey House, the History of Renvyle House
Published by Renvyle House Hotel, Galway, Ireland, in 1995.
Printed in Ireland by The Connacht Tribune Ltd. Bound by Kenny\u27s Bookshop, Galway.
134 p. col. ill., 20 cm.https://arrow.tudublin.ie/irckbooks/1109/thumbnail.jp
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