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

Signatures of Emerging Subsurface Structures in Acoustic Power Maps

We show that under certain conditions, subsurface structures in the solar interior can alter the average acoustic power observed at the photosphere above them. By using numerical simulations of wave propagation, we show that this effect is large enough for it to be potentially used for detecting emerging active regions before they appear on the surface. In our simulations, simplified subsurface structures are modeled as regions with enhanced or reduced acoustic wave speed. We investigate the dependence of the acoustic power above a subsurface region on the sign, depth, and strength of the wave speed perturbation. Observations from the Solar and Heliospheric Observatory/Michelson Doppler Imager (SOHO/MDI) prior and during the emergence of NOAA active region 10488 are used to test the use of acoustic power as a potential precursor of magnetic flux emergence.Comment: 7 pages, 5 figures, accepted for publication in Solar Physics on 21 March 201

Evaluation of distributed recharge in an upland semi-arid karst system: The west bank mountain aquifer, middle east.‖ Hydrogeol J

Abstract Assessment of recharge in a structurally complex upland karst limestone aquifer situated in a semi-arid environment is difficult. Resort to surrogate indicators such as measurement of spring outflow and borehole discharge, is a common alternative, and attempts to apply conventional soil moisture deficit analysis may not adequately account for the intermittent spate conditions that arise in such environments. A modelling approach has been made using the West Bank Mountain Aquifer system in the Middle East as a trial. The model uses object oriented software which allows various objects to be switched on and off. Each of the main recharge processes identified in the West Bank is incorporated. The model allows either conventional soil moisture deficit analysis calculations or wetting threshold calculations to be made as appropriate, and accommodates both direct recharge and secondary recharge. Daily time steps enable recharge and runoff routing to be calculated for each node. Model runs have enabled a series of simulations for each of the three aquifer basins in the West Bank and for the whole of the West Bank. These provide recharge estimates comparable to those prepared by earlier workers by conventional means. The model is adaptable and has been successfully used in other environments. Résumé Il est difficile d'évaluer la recharge d'un aquifère calcaire karstique qui présente une structure complexe et qui est localisé en montagne dans un environnement semiaride. Le recours à des indicateurs, tels que la mesure du débit d'une source ou le rendement d'un puits, représente une alternative commune, et essayer d'effectuer conventionnellement une analyse du déficit d'humidité du sol risque de ne pas prendre en compte les conditions associées aux crues intermittentes, lesquelles sont propres à de tels environnements. A titre d'essai, une approche par modélisation a été effectuée sur le système aquifère de West Bank Mountain au Moyen-Orient. Le modèle utilise un logiciel orienté objet, ce qui permet d'activer ou de désactiver un groupe d'objets. Chacun des principaux processus de recharge identifiés sur le West Bank est incorporé. Le modèle permet soit de réaliser des calculs conventionnels de déficit d'humidité du sol, soit de faire des calculs de seuil d'humidification et il permet de prendre en compte à la fois la recharge directe et la recharge secondaire. Des pas de temps journaliers permettent de calculer en chaque noeud la trajectoire de la recharge et du ruissellement. Le modèle a permis d'effectuer des séries de simulations pour chacun des trois bassins aquifères du West Bank ainsi que pour la totalité du West Bank. Ce travail a fourni des estimations comparables à celles obtenues précédemment par des moyens conventionnels. Ce modèle est transposable et a été appliqué avec succès à d'autres environnements. Resumen La evaluación de recarga en un acuífero de caliza kárstica estructuralmente complejo de tierras altas es difícil. Una alternativa común consiste en recurrir a indicadores sustitutos tal como la medición de descargas de manantial y descarga de sondeos mientras que los intentos de aplicar los análisis convencionales de déficit de humedad de suelo pueden no explicar adecuadamente para las condiciones torrenciales intermitentes que se presentan en tales ambientes. Se ha utilizado un enfoque de modelizado usando el sistema Acuífero de la Montaña del Banco Occidental en el Medio Oriente como prueba. El modelo usa un programa orientado al objeto el cual permite que varios objetos se enciendan y apaguen. Se incorpora cada uno de los principales procesos de recarga identificados en el Banco Occidental. El modelo permite ya sea cálculos convencionales de análisis de déficit de humedad de suelo o cálculos de umbrales de humedad para ser hechos como apropiados, acomodando tanto la recarga directa como la recarga secundaria. Los intervalos de tiempo diario permiten calcular para cada nodo las rutas de escorrentía y recarga. Las corridas del modelo han permitido una serie de simulaciones para cada una de las tres cuencas de acuíferos en el Banco Occidental y para todo el Banco Occidental. Las simulaciones aportan estimados de recarga que son comparables a los elaborados por investigadores previos usand

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