Atlas.txt : Exploring Lingusitic Grounding Techniques for Communicating Spatial Information to Blind Users

Peer reviewedPostprin

Evolving solitons in bubbly flows

At the end of the sixties, it was shown that pressure waves in a bubbly liquid obey the KdV equation, the nonlinear term coming from convective acceleration and the dispersive term from volume oscillations of the bubbles.\ud For a variableu, proportional to –p, wherep denotes pressure, the appropriate KdV equation can be casted in the formu t –6uu x +u xxx =0. The theory of this equation predicts that, under certain conditions, solitons evolve from an initial profileu(x,0). In particular, it can be shown that the numberN of those solitons can be found from solving the eigenvalue problem xx–u(x,0)=0, with(0)=1 and(0)=0.N is found from counting the zeros of the solution of this equation betweenx=0 andx=Q, say,Q being determined by the shape ofu(x,0). We took as an initial pressure profile a Shockwave, followed by an expansion wave. This can be realised in the laboratory and the problem, formulated above, can be solved exactly.\ud In this contribution the solution is outlined and it is shown from the experimental results that from the said initial disturbance, indeed solitons evolve in the predicated quantity.\u

The impact of culture and recipient perspective on direction giving in the service of wayfinding

We examined how culture and recipient perspective affect direction giving during wayfinding. Participants from the United States and the Netherlands provided directions from starting locations to destinations for fictional recipients driving through a town (route perspective) or looking at a map of the town (survey perspective). US participants provided street names more frequently than did Dutch participants, whereas Dutch participants provided landmarks more frequently than did US participants. Moreover, US participants provided more cardinal descriptors when addressing listeners adopting a survey perspective relative to a route perspective but more landmarks and left-right descriptors when addressing listeners adopting a route perspective relative to a survey perspective. Participants from the Netherlands evinced a similar pattern with the important distinction that they mostly ignored cardinal terms, unless explicitly primed to do so and in a survey condition. In addition, this very low usage of cardinal terms seemed to be replaced by using more landmark descriptions. This study revealed remarkable flexibility in people's spatial descriptions but also stressed major differences in the use of spatial terms between US and Dutch participants

Attrition of certified teachers in secondary education during the induction phase

Teacher attrition is generally considered problematically high, with attrition rates of beginning teachers up to 50%. This study shows the problem is not as big as has been claimed before. Previous studies have often focused on the attrition within 5 years, showing a quarter or more of beginning teachers leaving the profession. However, this disregards the fact that teachers leave at later stages as well, and the fact that some beginning teachers are not qualified to work as a teacher. Using administrative data from payroll administrations of schools in the Netherlands for secondary education a reliable measure of teacher attrition was made. Administrative data on diplomas in higher education were used to establish if teachers are certified at the start of their career. The results of this study show that the attrition rate of beginning teachers is only high within the first year of their career. The attrition rate within 1 year of experience is around 12% until the early 2000s, rising to close to 20% in more recent years. In comparison with other countries this seems relatively modest. However, after the first year, a base rate of attrition (retirement excluded) remains fairly constant at approximately 3% to 5% every year, explaining the gap with high attrition rates found in earlier studies. Attrition of certified teachers within one year is about 9%, with very little variation over time, versus the 12% to 20% of all beginning teachers. This 9% attrition rate of certified teachers is much lower than many earlier studies suggest

Skin Autofluorescence and Glycemic Variability

Background: Accumulation of advanced glycation end products (AGEs) is accelerated during glycemic and oxidative stress and is an important predictor of complications in diabetes mellitus (DM). Study Design: Here we both review and present original data on the relationship between skin autofluorescence (SAF), a noninvasive measure of AGEs, and short-and intermediate-term glycemic variations. Results: Acute changes in glucose levels during an oral glucose tolerance test in 56 persons with varying degrees of glucose tolerance did not influence SAF. AGE-rich meals result in a transient postprandial rise in SAF of 10% 2-4 h later. This could not be attributed to meal-induced glycemic changes and is probably caused by the AGE content of the meal. In type 1DM major intermediate-term improvements of glycemic control as depicted by multiple hemoglobin A1c (HbA1c) measurements were associated with lower skin AGE levels. In a well-controlled, stable type 2DM cohort, only a weak correlation was found between SAF and HbA1c. In both studies skin AGE/SAF levels predicted complications of diabetes with an accuracy superior to that of HbA1c. SAF has also been proposed as a new tool in diagnosing impaired glucose tolerance (IGT) and DM. It proved to be more sensitive than either fasting glucose or HbA1c. Conclusions: SAF is not influenced by short-term glycemic variations. AGE-rich meals may, however, cause a transient rise postprandially. There is a weak correlation between SAF or skin AGEs and current or time-integrated HbA1c levels. SAF has strong added value in risk prediction of complications of diabetes and is a promising tool for early detection of diabetes and IGT