Transition to turbulence in an elliptic vortex

We study the three dimensional instability and nonlinear growth of the two dimensional flow described by the stream function Psi = (A sin b1 x sin b2 y)/(b1(exp 2) + b2(exp 2)) where b1 = pi/L1, b2 = pi/L2. This is a swirling flow in a box which is bounded by 0 less than x less than L1, 0 less than y less than L2 and is infinite in the z direction. This flow is a solution of the Navier-Stokes equation with A = exp(-v(b1(exp 2) + b2(exp 2))t) which slowly decays. We seek a viscous solution which starts near this one and slips along but does not penetrate the bounding walls. The vorticity of the basic flow is w(sub z) = A sin b1 x sin b2 y which has maximum value A at the center of the box and drops to zero at the boundaries. We can think of the resulting flow as that of a captive vortex

Scaling and energy transfer in rotating turbulence

The inertial-range properties of quasi-stationary hydrodynamic turbulence under solid-body rotation are studied via high-resolution direct numerical simulations. For strong rotation the nonlinear energy cascade exhibits depletion and a pronounced anisotropy with the energy flux proceeding mainly perpendicularly to the rotation axis. This corresponds to a transition towards a quasi-two-dimensional flow similar to a linear Taylor-Proudman state. In contrast to the energy spectrum along the rotation axis which does not scale self-similarly, the perpendicular spectrum displays an inertial range with $k^{-2}_\perp$-behavior. A new phenomenology gives a rationale for the observations. The scaling exponents $\zeta_p$ of structure functions up to order $p=8$ measured perpendicular to the rotation axis indicate reduced intermittency with increasing rotation rate. The proposed phenomenology is consistent with the inferred asymptotic non-intermittent behavior $\zeta_p=p/2$.Comment: to be published in Europhysics Letters (www.epletters.net), minor changes to match version in prin

Storing pumpkin and winter squash at home

Suggests techniques to harvest, cure and store pumpkin and winter squash properly at home.Revised September 2009. Reviewed December 2014. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalogKeywords: storing pumpkin at home, harvesting squash at home, storing squash at home, curing squash at hom

Trans-sinusal frontal approach for olfactory groove meningiomas

Background We report on our experience with the trans-sinusal frontal approach in removing olfactory groove meningiomas in the department of neurosurgery of Univesity Hospital Center of Annaba (Algeria).Methods Ten tumours were operated on by the trans-sinusal frontal approach, using a bicoronal incision, tree tumours developed on one side, and there were seven bilateral olfactosellar tumours. Our procedure : steotomy of the anterior wall of the frontal sinus was performed with an oscillating saw. The posterior wall of the sinus was resected and the tumour was removed through a real subfrontal route along the plane of the anterior skull base. Ethmoidal blood supply was early controlled at the initial stages of the operation, allowing avascular tumour debulking. Tumour extensions toward the sella and the optic canals were removed without brain retraction. Results Seven patients made a good neurologic recovery. Two was dead in the 24 hours after intervention and one four days after. Olfactory nets were preserved on the contralateral side in unilateral tumours. Conclusions The trans-sinusal frontal approach represents an excellent way for tumours developed in the central anterior skull base, especially for olfactory groove meningiomas, whatever their size

Exploring the ontological dimension of dialogic education through an evaluation of the impact of Internet mediated dialogue across cultural difference

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.It has been claimed that dialogic education implies a direction of change upon an ontological dimension from monologic closed identities in the direction of more dialogic identifications characterised by greater openness to the other and greater identification with the process of dialogue. This paper recapitulates that theory and then provides an empirical illustration of what it looks like in practice. In order to do this a methodology for researching the impact of dialogic education is outlined and applied to the evaluation of the impact of a programme designed to promote greater dialogic open-mindedness: the Tony Blair Institute for Global Change’s Generation Global Project (GG) supports schools in over twenty different countries to engage in dialogue with each other through videos and blogs. The methodology put forward argues that the understanding sought by educational research is dialogic in that it emerges from the dialogue between inside and outside perspectives. The findings offer some clear evidence of a shift in identifications resulting from dialogue through the analysis of changes in online language use supported by interview evidence. This study suggests that a pedagogical intervention can produce identity change in the direction of becoming more dialogic and shows that it is possible to evaluate this change.The empirical aspect of this paper reports on research funded by the Tony Blair Institute for Global Change

VEP oscillation solutions to the solar neutrino problem

We study the solar neutrino problem within the framework of a parametrized post-Newtonian formulation for the gravitational interaction of the neutrinos, which incorporates a violation to the equivalence principle (VEP). Using the current data on the rates and the energy spectrum we find two possible oscillation solutions, both for a large mixing angle. One of them involves the MSW effect in matter and the other corresponds to vacuum oscillations. An interesting characteristic of this mechanism is that it predicts a semi-annual variation of the neutrino flux. Our analysis provides new constraints for some VEP parameters.Comment: revtex, 18 pages, 11 figure