1,936 research outputs found
Community building and virtual teamwork in an online learning environment
In the world of OTIS, an online Internet School for occupational therapists, students from four European countries were encouraged to work collaboratively through problem based learning by interacting with each other in a virtual semi-immersive environment. This paper aims to explore the issues that there was little interaction between students from different tutorial groups and virtual teamwork developed in each of the cross cultural tutorial groups. Synchronous data from European students was captured during tutorial sessions and peer booked meetings and evidence suggests that communities of interest were established. It is possible to conclude that collaborative systems can be designed, which encourage students to build trust and teamwork in a cross cultural online learning environment. </p
Multiclass Hammersley-Aldous-Diaconis process and multiclass-customer queues
In the Hammersley-Aldous-Diaconis process infinitely many particles sit in R
and at most one particle is allowed at each position. A particle at x$ whose
nearest neighbor to the right is at y, jumps at rate y-x to a position
uniformly distributed in the interval (x,y). The basic coupling between
trajectories with different initial configuration induces a process with
different classes of particles. We show that the invariant measures for the
two-class process can be obtained as follows. First, a stationary M/M/1 queue
is constructed as a function of two homogeneous Poisson processes, the arrivals
with rate \lambda and the (attempted) services with rate \rho>\lambda. Then put
the first class particles at the instants of departures (effective services)
and second class particles at the instants of unused services. The procedure is
generalized for the n-class case by using n-1 queues in tandem with n-1
priority-types of customers. A multi-line process is introduced; it consists of
a coupling (different from Liggett's basic coupling), having as invariant
measure the product of Poisson processes. The definition of the multi-line
process involves the dual points of the space-time Poisson process used in the
graphical construction of the system. The coupled process is a transformation
of the multi-line process and its invariant measure the transformation
described above of the product measure.Comment: 21 pages, 6 figure
Generalized Voronoi Tessellation as a Model of Two-dimensional Cell Tissue Dynamics
Voronoi tessellations have been used to model the geometric arrangement of
cells in morphogenetic or cancerous tissues, however so far only with flat
hypersurfaces as cell-cell contact borders. In order to reproduce the
experimentally observed piecewise spherical boundary shapes, we develop a
consistent theoretical framework of multiplicatively weighted distance
functions, defining generalized finite Voronoi neighborhoods around cell bodies
of varying radius, which serve as heterogeneous generators of the resulting
model tissue. The interactions between cells are represented by adhesive and
repelling force densities on the cell contact borders. In addition, protrusive
locomotion forces are implemented along the cell boundaries at the tissue
margin, and stochastic perturbations allow for non-deterministic motility
effects. Simulations of the emerging system of stochastic differential
equations for position and velocity of cell centers show the feasibility of
this Voronoi method generating realistic cell shapes. In the limiting case of a
single cell pair in brief contact, the dynamical nonlinear Ornstein-Uhlenbeck
process is analytically investigated. In general, topologically distinct tissue
conformations are observed, exhibiting stability on different time scales, and
tissue coherence is quantified by suitable characteristics. Finally, an
argument is derived pointing to a tradeoff in natural tissues between cell size
heterogeneity and the extension of cellular lamellae.Comment: v1: 34 pages, 19 figures v2: reformatted 43 pages, 21 figures, 1
table; minor clarifications, extended supplementary materia
Language of Lullabies: The Russification and De-Russification of the Baltic States
This article argues that the laws for promotion of the national languages are a legitimate means for the Baltic states to establish their cultural independence from Russia and the former Soviet Union
Global standards of Constitutional law : epistemology and methodology
Just as it led the philosophy of science to gravitate around scientific practice, the abandonment of all foundationalist aspirations has already begun making political philosophy into an attentive observer of the new ways in which constitutional law is practiced. Yet paradoxically, lawyers and legal scholars are not those who understand this the most clearly. Beyond analyzing the jurisprudence that has emerged from the expansion of constitutional justice, and taking into account the development of international and regional law, the ongoing globalization of constitutional law requires comparing the constitutional laws of individual nations. Following Waldron, the product of this new legal science can be considered as ius gentium. This legal science is not as well established as one might like to think. But it can be developed on the grounds of the practice that consists in ascertaining standards. As abstract types of best “practices” (and especially norms) of constitutional law from around the world, these are only a source of law in a substantive, not a formal, sense. They thus belong to what I should like to call a “second order legal positivity.” In this article I will undertake, both at a methodological and an epistemological level, the development of a model for ascertaining global standards of constitutional law
Beam instrumentation for the Tevatron Collider
The Tevatron in Collider Run II (2001-present) is operating with six times
more bunches and many times higher beam intensities and luminosities than in
Run I (1992-1995). Beam diagnostics were crucial for the machine start-up and
the never-ending luminosity upgrade campaign. We present the overall picture of
the Tevatron diagnostics development for Run II, outline machine needs for new
instrumentation, present several notable examples that led to Tevatron
performance improvements, and discuss the lessons for future colliders
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