2,782 research outputs found
Reclaimed Identity/Innov - Roc: the Innovation Hub + Revitalization of High Falls, Rochester, NY
This project is not about creating a piece of architecture that will serve as an icon to an idea or movement. Rather, this project is about how a series of smaller architectural interventions can reinforce a context that is already established and has roots that can be traced back to the city’s founding. A series of smaller programs linked together, and to the larger urban context will serve as a means of re-energizing this forgotten district, and re-energizing a city that has been in steady decline for the last several decades. The project must draw on several community partners and organizations, and the unique skills, services, and opportunities that can offer each other, and the community as a whole
Separating invariants for arbitrary linear actions of the additive group
We consider an arbitrary representation of the additive group G_a
over a field of characteristic zero and give an explicit description of a finite separating set in the corresponding ring of invariants
The Cohen-Macaulay property of separating invariants of finite groups
In the case of finite groups, a separating algebra is
a subalgebra of the ring of invariants which separates the orbits.
Although separating algebras are often better behaved than the
ring of invariants, we show that many of the criteria which imply
the ring of invariants is non Cohen-Macaulay actually imply that
no graded separating algebra is Cohen-Macaulay. For example, we
show that, over a field of positive characteristic p, given sufficiently
many copies of a faithful modular representation, no graded sep-
arating algebra is Cohen-Macaulay. Furthermore, we show that,
for a p-group, the existence of a Cohen-Macaulay graded separat-
ing algebra implies the group is generated by bireflections. Ad-
ditionally, we give an example which shows that Cohen-Macaulay
separating algebras can occur when the ring of invariants is not
Cohen-Macaulay
Brownian Dynamics of a Sphere Between Parallel Walls
We describe direct imaging measurements of a colloidal sphere's diffusion
between two parallel surfaces. The dynamics of this deceptively simple
hydrodynamically coupled system have proved difficult to analyze. Comparison
with approximate formulations of a confined sphere's hydrodynamic mobility
reveals good agreement with both a leading-order superposition approximation as
well as a more general all-images stokeslet analysis.Comment: 4 pages, 3 figures, REVTeX with PostScript figure
Plasticized Starch/ Tunicin Whiskers Nanocomposites : 1. Structural Analysis
International audienceNanocomposite materials were obtained using glycerol plasticized starch as the matrix and a colloidal suspension of cellulose whiskers as the reinforcing phase. The cellulose whiskers, prepared from tunicin, consisted of slender parallelepiped rods with a high aspect ratio. After mixing the raw materials and gelatinization of starch, the resulting suspension was cast and evaporated under vacuum. The composites were conditioned at various moisture contents in order to evaluate the effect of this parameter on the composite structure. Th
Complementarities Between Physical Modelling and Computational Fluid Dynamics for an Ecological Continuity Project
This study presents a comparison between physical modelling and computational fluid dynamics (CFD) for investigating ecological continuity of the Poutès dam modification project. Water depth and velocity measurements have been carried out in the whole physical model. A CFD model has been built based on the geometry of the physical model. Simulations were performed using the OpenFOAM software and the InterFoam solver. Water depths and velocities have been extracted from the numerical model and compared to measurements. The agreement is very good for water depths and quite good for velocities
A shadowing problem in the detection of overlapping communities: lifting the resolution limit through a cascading procedure
Community detection is the process of assigning nodes and links in
significant communities (e.g. clusters, function modules) and its development
has led to a better understanding of complex networks. When applied to sizable
networks, we argue that most detection algorithms correctly identify prominent
communities, but fail to do so across multiple scales. As a result, a
significant fraction of the network is left uncharted. We show that this
problem stems from larger or denser communities overshadowing smaller or
sparser ones, and that this effect accounts for most of the undetected
communities and unassigned links. We propose a generic cascading approach to
community detection that circumvents the problem. Using real and artificial
network datasets with three widely used community detection algorithms, we show
how a simple cascading procedure allows for the detection of the missing
communities. This work highlights a new detection limit of community structure,
and we hope that our approach can inspire better community detection
algorithms.Comment: 14 pages, 12 figures + supporting information (5 pages, 6 tables, 3
figures
Propagation dynamics on networks featuring complex topologies
Analytical description of propagation phenomena on random networks has
flourished in recent years, yet more complex systems have mainly been studied
through numerical means. In this paper, a mean-field description is used to
coherently couple the dynamics of the network elements (nodes, vertices,
individuals...) on the one hand and their recurrent topological patterns
(subgraphs, groups...) on the other hand. In a SIS model of epidemic spread on
social networks with community structure, this approach yields a set of ODEs
for the time evolution of the system, as well as analytical solutions for the
epidemic threshold and equilibria. The results obtained are in good agreement
with numerical simulations and reproduce random networks behavior in the
appropriate limits which highlights the influence of topology on the processes.
Finally, it is demonstrated that our model predicts higher epidemic thresholds
for clustered structures than for equivalent random topologies in the case of
networks with zero degree correlation.Comment: 10 pages, 5 figures, 1 Appendix. Published in Phys. Rev. E (mistakes
in the PRE version are corrected here
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