9,772 research outputs found
Quantitative estimates for the flux of TASEP with dilute site disorder
We prove that the flux function of the totally asymmetric simple exclusion
process (TASEP) with site disorder exhibits a flat segment for sufficiently
dilute disorder. For high dilution, we obtain an accurate description of the
flux. The result is established undera decay assumption of the maximum current
in finite boxes, which is implied in particular by a sufficiently slow power
tail assumption on the disorder distribution near its minimum. To circumvent
the absence of explicit invariant measures, we use an original renormalization
procedure and some ideas inspired by homogenization
Do Convolutional Networks need to be Deep for Text Classification ?
We study in this work the importance of depth in convolutional models for
text classification, either when character or word inputs are considered. We
show on 5 standard text classification and sentiment analysis tasks that deep
models indeed give better performances than shallow networks when the text
input is represented as a sequence of characters. However, a simple
shallow-and-wide network outperforms deep models such as DenseNet with word
inputs. Our shallow word model further establishes new state-of-the-art
performances on two datasets: Yelp Binary (95.9\%) and Yelp Full (64.9\%)
Topography influence on the Lake equations in bounded domains
We investigate the influence of the topography on the lake equations which
describe the two-dimensional horizontal velocity of a three-dimensional
incompressible flow. We show that the lake equations are structurally stable
under Hausdorff approximations of the fluid domain and perturbations of
the depth. As a byproduct, we obtain the existence of a weak solution to the
lake equations in the case of singular domains and rough bottoms. Our result
thus extends earlier works by Bresch and M\'etivier treating the lake equations
with a fixed topography and by G\'erard-Varet and Lacave treating the Euler
equations in singular domains
Planet gaps in the dust layer of 3D proto-planetary disks: Observability with ALMA
Among the numerous known extrasolar planets, only a handful have been imaged
directly so far, at large orbital radii and in rather evolved systems. The
Atacama Large Millimeter/submillimeter Array (ALMA) will have the capacity to
observe these wide planetary systems at a younger age, thus bringing a better
understanding of the planet formation process. Here we explore the ability of
ALMA to detect the gaps carved by planets on wide orbits.Comment: 2 pages, 2 figures, to appear in the Proceedings of IAU Symp. 299:
Exploring the Formation and Evolution of Planetary Systems (Victoria, Canada
Hadwiger number of graphs with small chordality
The Hadwiger number of a graph G is the largest integer h such that G has the
complete graph K_h as a minor. We show that the problem of determining the
Hadwiger number of a graph is NP-hard on co-bipartite graphs, but can be solved
in polynomial time on cographs and on bipartite permutation graphs. We also
consider a natural generalization of this problem that asks for the largest
integer h such that G has a minor with h vertices and diameter at most . We
show that this problem can be solved in polynomial time on AT-free graphs when
s>=2, but is NP-hard on chordal graphs for every fixed s>=2
Asymptotically AdS brane black holes
We study the possibility of having a static, asymptotically AdS black hole
localized on a braneworld with matter fields, within the framework of the
Randall and Sundrum scenario. We attempt to look for such a brane black hole
configuration by slicing a given bulk spacetime and taking Z_2 symmetry about
the slices. We find that such configurations are possible, and as an explicit
example, we provide a family of asymptotically AdS brane black hole solutions
for which both the bulk and brane metrics are regular on and outside the black
hole horizon and brane matter fields are realistic in the sense that the
dominant energy condition is satisfied. We also find that our braneworld models
exhibit signature change inside the black hole horizon.Comment: 21 pages, 6 figures, RevTex; v2: clarifications added, figures
updated, eq.31 corrected, comment on small four dimensional cosmological
constant limit added, character size increased, results unchanged. v3:
reference added, version accepted in Phys. Rev. D (2006
Why does wurtzite form in nanowires of III-V zinc-blende semiconductors?
We develop a nucleation-based model to explain the formation of the wurtzite
(WZ) crystalline phase during the vapor-liquid-solid growth of free-standing
nanowires of zinc-blende (ZB) semiconductors. We first show that, in nanowires,
nucleation generally occurs at the outer edge of the solid/liquid interface
(the triple phase line) rather than elsewhere at the solid/liquid interface. In
the present case, this entails major differences between ZB and WZ nuclei.
Depending on the pertinent interface energies, WZ nucleation is favored at high
liquid supersaturation. This explains our systematic observation of ZB during
the early stages of nanowire growth.Comment: 4 pages with 4 figures Submitted to Physical Review Letter
- …