Geometry and dynamics of vortex sheets in 3 dimensions

We consider the properties and dynamics of vortex sheets from a geometrical, coordinate-free, perspective. Distribution-valued forms (de Rham currents) are used to represent the fluid velocity and vorticity due to the vortex sheets. The smooth velocities on either side of the sheets are solved in terms of the sheet strengths using the language of double forms. The classical results regarding the continuity of the sheet normal component of the velocity and the conservation of vorticity are exposed in this setting. The formalism is then applied to the case of the self-induced velocity of an isolated vortex sheet. We develop a simplified expression for the sheet velocity in terms of representative curves. Its relevance to the classical Localized Induction Approximation (LIA) to vortex filament dynamics is discusse

Vietnamese Women and Children Refugees in Hong Kong: An Argument against Arbitrary Detention

Anteckningar från Sundre, Gotland sydligaste socken. Onsdag 11 april 2012 Rivet, en smal udde av grus. Stark vind, öppen horisont. Vatten på nära nog alla håll. Här, längst ut, drabbades jag av fasa när havet ville döda mig, sluka min kropp. Letade efter gravarna men fann inget. Gick upp till Arendt i fyren. --- Mitt examensprojekt är min promenad tillsammans med historia, tempo, minne, tröghet, förflyttningar och förändringar, ruiner, myter samt högst personliga reflektioner. Det finns platser man verkligen tycker om, som man älskar. Jag vet flera platser som jag älskar att vara på, det här är en av dem. Få stannar till här, det är ett ställe man passerar. Jag vill vara ensam här. Vid mina besök, som på senare tid under projektets gång har varit mycket riktade, blir jag extremt fokuserad på platsen och bara platsen. Också som att kliva ur tjockan.Notes from the parish of Sundre, at the very south of Gotland. Wednesday April 11, 2012 Rivet, a small cpe of gravel. Strong wind, open horizon. Water in almost all directions. Here, at the nab, fright hit me when the sea wanted to liquidate me, swallow my body. Searched for the tombs but found nothing. Visited Arendt in the lighthouse. --- My degree project is my promenade together with history, tempo, memory, inertia, movements, ruins, myths and my very personal reflections. There are places you really like, that you love. There are several places that I love to be at, this is one of them. Few people halt here, this is a place you pass. I want to be alone here. At my visits, that during the project became more and more addressed, I become extremely focused at the place and the place only. Like stepping out of the mist

A study of the understanding of knowledge and learning of a cohort of mature age students

In 2005 the authors began a longitudinal research project to explore the factors that influence student success in the Master of Engineering Practice program which was offered for the first time in Semester 2, 2004. This distance education program enables experienced Engineering Technologists to use their workplace learning to gain a qualification at the Professional Engineer level. This research was initiated because the admission of some students into the program is based on the recognition of their prior workplace learning. Cantwell and Scevak (2004) highlighted the problems that students may encounter when they gain entry to a university on this basis. To explore this issue four previously validated questionnaires were used to gather data on: student approaches to learning, their epistemological beliefs, learning style preferences, and strategic flexibility. This paper reports on a preliminary analysis of the data gathered from the students who enrolled in the program during the period 2005-2009. In the longer term, when the sample size has grown and more students have graduated, the data will be analysed to explore the relationship between the measured factors and success at university

Twisted Electromagnetic Modes and Sagnac Ring-Lasers

A new approximation scheme, designed to solve the covariant Maxwell equations inside a rotating hollow slender conducting cavity (modelling a ring-laser), is constructed. It is shown that for well-defined conditions there exist TE and TM modes with respect to the longitudinal axis of the cavity. A twisted mode spectrum is found to depend on the integrated Frenet torsion of the cavity and this in turn may affect the Sagnac beat frequency induced by a non-zero rotation of the cavity. The analysis is motivated by attempts to use ring-lasers to measure terrestrial gravito-magnetism or the Lense-Thirring effect produced by the rotation of the Earth.Comment: LaTeX 31 pages, 3 Figure

Aspen Delineation Project 2003 Summary Report

The 2003 report summarizes the second year of the Aspen Delineation Project (ADP) as a project cosponsored by the Forest Service, Pacific Southwest Region; California State Office, Bureau of Land Management; and California Department of Fish and Game. David Burton, the Principal Investigator of the Aspen Delineation Project, works under the direction of Hugh Safford (FS), Ed Lorentzen (BLM), and Eric Loft (CDFG)

A primary care Symptoms Clinic for patients with medically unexplained symptoms : pilot randomised trial

Peer reviewedPublisher PD