Approximation of symmetrizations by Markov processes

Under continuity and recurrence assumptions, we prove that the iteration of successive partial symmetrizations that form a time-homogeneous Markov process, converges to a symmetrization. We cover several settings, including the approximation of the spherical nonincreasing rearrangement by Steiner symmetrizations, polarizations and cap symmetrizations. A key tool in our analysis is a quantitative measure of the asymmetry

Vortex motion for the lake equations

The lake equations $$\left\{\begin{aligned} \nabla \cdot \big( b \, \mathbf{u}\big) &= 0 & & \text{on}\ \mathbb{R}\times D,\\ \partial_t\mathbf{u} + (\mathbf{u}\cdot \nabla)\mathbf{u} &= -\nabla h & & \text{on}\ \mathbb{R}\times D ,\\ \mathbf{u} \cdot \boldsymbol{\nu} &= 0 & & \text{on}\ \mathbb{R}\times\partial D . \end{aligned}\right.$$ model the vertically averaged horizontal velocity in an inviscid incompressible flow of a fluid in a basin whose variable depth $b : D \to [0, + \infty)$ is small in comparison with the size of its two-dimensional projection $D \subset \mathbb{R}^2$. When the depth $b$ is positive everywhere in $D$ and constant on the boundary, we prove that the vorticity of solutions of the lake equations whose initial vorticity concentrates at an interior point is asympotically a multiple of a Dirac mass whose motion is governed by the depth function $b$.Comment: Minor revision, 43 page

A simple time-management tool for students' online learning activities

[Abstract]: Student time-management practices are a significant contributing factor to success in tertiary education, particularly in online and blended learning. In courses where many tasks are set to involve students continuously, a learning management system can be used to structure and assist time-management. This paper reports on the successful development and testing of a simple time-management tool that can assist students within an LMS

Range convergence monotonicity for vector measures and range monotonicity of the mass

We prove that the range of sequence of vector measures converging widely satisfies a weak lower semicontinuity property, that the convergence of the range implies the strict convergence (convergence of the total variation) and that the strict convergence implies the range convergence for strictly convex norms. In dimension 2 and for Euclidean spaces of any dimensions, we prove that the total variation of a vector measure is monotone with respect to the range.Comment: 28 page

Pre-therapy process and outcome: A review of research instruments and findings

Pre-Therapy aims at stimulating psychological contact in persons suffering psychosis. We offer a review of Pre-Therapy research instruments and findings. The Pre-Therapy Rating Scale (PTRS, Prouty, 1994) and the Evaluation Criterion for the Pre-Therapy Interview (ECPI, Dinacci, 1997) have been the two most frequently used instruments for the assessment of psychological contact. PTRS scores seem more reliable than ECPI scores, but all manuals need revision. Particular attention is needed for the rating of nonverbal behavior. A preliminary evaluation of the structure of the PTRS indicates that it is two-dimensional rather than three-dimensional. The PTRS and the ECPI can be regarded as measures of communicative contact but also as measures of the meaningfulness of communication. Preliminary outcome studies suggest that pre-post and comparative effect sizes of Pre-Therapy are large for communicative contact, but the number of participants in these studies is generally low, as is the number of systematic case studies

Instance-Independent View Serializability for Semistructured Databases

Semistructured databases require tailor-made concurrency control mechanisms since traditional solutions for the relational model have been shown to be inadequate. Such mechanisms need to take full advantage of the hierarchical structure of semistructured data, for instance allowing concurrent updates of subtrees of, or even individual elements in, XML documents. We present an approach for concurrency control which is document-independent in the sense that two schedules of semistructured transactions are considered equivalent if they are equivalent on all possible documents. We prove that it is decidable in polynomial time whether two given schedules in this framework are equivalent. This also solves the view serializability for semistructured schedules polynomially in the size of the schedule and exponentially in the number of transactions

Land Investments, Food Systems Change and Democracy in Kenya and Mozambique

In Africa, food systems intersect with dynamics such as demographic growth, urbanisation, and climate change, as African food systems are key drivers of livelihood provision, development, and human-environment interactions. The governance of African food systems shapes how food systems are changing as a response to these dynamics, which will have important social, economic, and ecological impacts for generations of Africans. This article positions large land investments in food system changes in central Kenya and northern Mozambique based on a large-scale household survey and interviews, and uses these findings to debate the concept of food democracy. Large land investments contributed to more modern food systems, which impacted land availability, household’s engagement in agriculture, and supply chains. These changes shifted power and control in local food systems. But even in the ‘extreme’ example of land investments, local perspectives challenge what could, and could not, be included in a democratic food system