6,979 research outputs found
Grand Illusions: Large-Scale Optical Toys and Contemporary Scientific Spectacle
Nineteenth-century optical toys that showcase illusions of motion such as the phenakistoscope, zoetrope, and praxinoscope, have enjoyed active “afterlives” in the twentieth and twenty-first centuries. Contemporary incarnations of the zoetrope are frequently found in the realms of fine art and advertising, and they are often much larger than their nineteenth-century counterparts. This article argues that modern-day optical toys are able to conjure feelings of wonder and spectacle equivalent to their nineteenth-century antecedents because of their adjustment in scale. Exploring a range of contemporary philosophical toys found in arts, entertainment, and advertising contexts, the article discusses various technical adjustments made to successfully “scale up” optical toys, including the replacement of hand-spun mechanisms with larger sources of motion and the use of various means such as architectural features and stroboscopic lights to replace traditional shutter mechanisms such as the zoetrope’s dark slots. Critical consideration of scale as a central feature of these installations reconfigures the relationship between audience and device. Large-scale adaptations of optical toys revise the traditional conception of the user, who is able to tactilely manipulate and interact with the apparatus, instead positing a viewer who has less control over the illusion’s operation and is instead a captive audience surrounded by the animation. It is primarily through their adaptation of scale that contemporary zoetropes successfully elicit wonder as scientific spectacles from their audiences today
Local-Global Principle for Transvection Groups
In this article we extend the validity Suslin's Local-Global Principle for
the elementary transvection subgroup of the general linear group, the
symplectic group, and the orthogonal group, where n > 2, to a Local-Global
Principle for the elementary transvection subgroup of the automorphism group
Aut(P) of either a projective module P of global rank > 0 and constant local
rank > 2, or of a nonsingular symplectic or orthogonal module P of global
hyperbolic rank > 0 and constant local hyperbolic rank > 2. In Suslin's
results, the local and global ranks are the same, because he is concerned only
with free modules. Our assumption that the global (hyperbolic) rank > 0 is used
to define the elementary transvection subgroups. We show further that the
elementary transvection subgroup ET(P) is normal in Aut(P), that ET(P) = T(P)
where the latter denotes the full transvection subgroup of Aut(P), and that the
unstable K_1-group K_1(Aut(P)) = Aut(P)/ET(P) = Aut(P)/T(P) is nilpotent by
abelian, provided R has finite stable dimension. The last result extends
previous ones of Bak and Hazrat for the above mentioned classical groups.
An important application to the results in the current paper can be found in
the work of last two named authors where they have studied the decrease in the
injective stabilization of classical modules over a non-singular affine algebra
over perfect C_1-fields. We refer the reader to that article for more details.Comment: 15 page
Length Scales and Power Laws in the Two-Dimensional Forest-Fire Model
We re-examine a two-dimensional forest-fire model via Monte-Carlo simulations
and show the existence of two length scales with different critical exponents
associated with clusters and with the usual two-point correlation function of
trees. We check resp. improve previously obtained values for other critical
exponents and perform a first investigation of the critical behaviour of the
slowest relaxational mode. We also investigate the possibility of describing
the critical point in terms of a distribution of the global density. We find
that some qualitative features such as a temporal oscillation and a power law
of the cluster-size distribution can nicely be obtained from such a model that
discards the spatial structure.Comment: 20 pages plain TeX, 7 figures included using psfig.sty, PostScript
for the complete paper also available at
http://www.physik.fu-berlin.de/~ag-peschel/papers/forest2d.ps.gz , extra
software at http://www.physik.fu-berlin.de/~ag-peschel/software/forest2d.html
; main change: inclusion of further data in the determination of nu_T in
Section 2.1 + some small changes; final version to appear in Physica
A remark on the Brylinski conjecture for orbifolds
We present reformulation of Mathieu's result on representing cohomology
classes of symplectic manifold with symplectically harmonic forms. We apply it
to the case of foliated manifolds with transversally symplectic structure and
to symplectic orbifolds. We obtain in particular that such representation is
always possible for compact K\"{a}hler orbifolds.Comment: 10 page
Self-organization of structures and networks from merging and small-scale fluctuations
We discuss merging-and-creation as a self-organizing process for scale-free
topologies in networks. Three power-law classes characterized by the power-law
exponents 3/2, 2 and 5/2 are identified and the process is generalized to
networks. In the network context the merging can be viewed as a consequence of
optimization related to more efficient signaling.Comment: Physica A: Statistical Mechanics and its Applications, In Pres
Disorder-induced phase transition in a one-dimensional model of rice pile
We propose a one-dimensional rice-pile model which connects the 1D BTW
sandpile model (Phys. Rev. A 38, 364 (1988)) and the Oslo rice-pile model
(Phys. Rev. lett. 77, 107 (1997)) in a continuous manner. We found that for a
sufficiently large system, there is a sharp transition between the trivial
critical behaviour of the 1D BTW model and the self-organized critical (SOC)
behaviour. When there is SOC, the model belongs to a known universality class
with the avalanche exponent .Comment: 10 pages, 7 eps figure
Different hierarchy of avalanches observed in the Bak-Sneppen evolution model
We introduce a new quantity, average fitness, into the Bak-Sneppen evolution
model. Through the new quantity, a different hierarchy of avalanches is
observed. The gap equation, in terms of the average fitness, is presented to
describe the self-organization of the model. It is found that the critical
value of the average fitness can be exactly obtained. Based on the simulations,
two critical exponents, avalanche distribution and avalanche dimension, of the
new avalanches are given.Comment: 5 pages, 3 figure
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