20,022 research outputs found
“Disguised in scarlet”. Hume and Turin in 17481
Archive Research concerning the following subjects: Hume in Turin (8 May - 29 November 1748) as secretary and aide-de-camp to General St Clair. St Clair's mission and correspondence (his letters written by Hume). Hume's account of plains and fortifications (the principle of sympathy). Hume's maladay and religion. 'Of National Characters' and Hume's reading of Montesquieu's Esprit. Hume and Lord Charlemont
Core Decomposition in Multilayer Networks: Theory, Algorithms, and Applications
Multilayer networks are a powerful paradigm to model complex systems, where
multiple relations occur between the same entities. Despite the keen interest
in a variety of tasks, algorithms, and analyses in this type of network, the
problem of extracting dense subgraphs has remained largely unexplored so far.
In this work we study the problem of core decomposition of a multilayer
network. The multilayer context is much challenging as no total order exists
among multilayer cores; rather, they form a lattice whose size is exponential
in the number of layers. In this setting we devise three algorithms which
differ in the way they visit the core lattice and in their pruning techniques.
We then move a step forward and study the problem of extracting the
inner-most (also known as maximal) cores, i.e., the cores that are not
dominated by any other core in terms of their core index in all the layers.
Inner-most cores are typically orders of magnitude less than all the cores.
Motivated by this, we devise an algorithm that effectively exploits the
maximality property and extracts inner-most cores directly, without first
computing a complete decomposition.
Finally, we showcase the multilayer core-decomposition tool in a variety of
scenarios and problems. We start by considering the problem of densest-subgraph
extraction in multilayer networks. We introduce a definition of multilayer
densest subgraph that trades-off between high density and number of layers in
which the high density holds, and exploit multilayer core decomposition to
approximate this problem with quality guarantees. As further applications, we
show how to utilize multilayer core decomposition to speed-up the extraction of
frequent cross-graph quasi-cliques and to generalize the community-search
problem to the multilayer setting
Higher Hamming weights for locally recoverable codes on algebraic curves
We study the locally recoverable codes on algebraic curves. In the first part
of this article, we provide a bound of generalized Hamming weight of these
codes. Whereas in the second part, we propose a new family of algebraic
geometric LRC codes, that are LRC codes from Norm-Trace curve. Finally, using
some properties of Hermitian codes, we improve the bounds of distance proposed
in [1] for some Hermitian LRC codes.
[1] A. Barg, I. Tamo, and S. Vlladut. Locally recoverable codes on algebraic
curves. arXiv preprint arXiv:1501.04904, 2015
Characterization of optimal carbon nanotubes under stretching and validation of the Cauchy-Born rule
Carbon nanotubes are modeled as point configurations and investigated by
minimizing configurational energies including two-and three-body interactions.
Optimal configurations are identified with local minima and their fine geometry
is fully characterized in terms of lower-dimensional problems. Under moderate
tension, we prove the existence of periodic local minimizers, which indeed
validates the so-called Cauchy-Born rule in this setting.Comment: The final publication is available at springerlink.co
Evaluation of Human-impacted Soils in Szeged (SE Hungary) with Special Emphasis on Physical, Chemical and Biological Properties
The main differences between urban and natural soils result from the accumulation
of anthropogenic materials, which form a cultural layer with specific
properties and composition. Szeged is an ideal sampling area for researching
urban soils due to intensive artificial infill following the 1879 Great Flood as
well as other anthropogenic activities owing to the expansion of urban functions
that define the morphology of soils here. We took samples at 25 sites in 2005
and 2006 from horizons of soil profiles located in city areas and peripheral
profiles of the original genetic soil type for physical and chemical analysis.
Average topsoil samples (0-10 cm depth, 2-4 m2) were taken near the profiles in
order to determine the concentrations of heavy metals (Co, Cu, Ni, Pb, Zn, Cr,
Cd) in these soils so as to classify them according to the toxic properties
described in the World Reference Base for Soil Resources and to identify the
origins of these elements (anthropogenic vs. geogenic). Topsoil samples were
also collected in October 2006 at 10 sites representing three zones (city,
suburban, peripheral zone) to survey some basic biological properties of mesofaunal
elements and their community structure.
We claim that all the soil parameters except total salt content are excellent
markers of human influence. This is well supported by a discriminant analysis of
the above-mentioned parameters. In our analysis of heavy metals, we distinguished
elements of anthropogenic (Cu, Ni, Pb, Zn) and natural or lithogenic
(Co, Cr, Cd) origin. Following a quantitative evaluation of elements, according
to the proposal of the World Reference Base for Soil Resources, profiles where
the concentration of any metal element exceeded the limit values in the topsoil
were marked with the suffix Toxic. According to a mezofauna (oribatid mites,
collembolans) investigation, it seems that the intermediate suburban zone has a
more heterogeneous and stable mezofaunal community structure than the other
two zones. The lowest abundance values were found in the city zone. Based on
our evaluation of diagnostic properties and the results of our discriminant
analysis, four main soil types can be identified in Szeged related to the degree of
human influence
Mechanical testing of metallic foams for 3d model and simulation of cell distribution effects
Cellular materials have a bulk matrix with a larger number of voids named also cells. Metallic foams made by powder technology represent stochastic closed cells. The related inhomogeneity leads to a scattering of results both in terms of stress–strain curves and maximum strength. Scattering is attributed to relative density variations and local cell discontinuities and it is confirmed also in case of dynamic loading. Finite element simulations through geometrical models that are able to capture the void morphology (named “mesoscale models”), confirm these results and some efforts have been already done to quantify the relationship between shape irregularities and mechanical behavior. The aim of this paper is to present the dynamic characterization of an AA7075 closed cell material and to calibrate its mesoscale finite element model according to the related cell shape distribution. Specimens have been derived from a small ingot (45x45x100 mm) divided along sections so that morphological analysis and experimental tests have been carried out. Specimens extracted from a half of the ingot have been used for dynamic compression tests by means of a split Hopkinson bar, meanwhile specimens extracted from the other half of the ingot have been dissected for porosity distribution analyses carried out by means of image analysis. Stress-strain curves obtained from the mechanical tests have been discussed in terms of strain rate and statistical descriptors of the porosity. Successively a 3D-model of the specimen has been generated starting from the Voronoi algorithm, assigning as input the above-mentioned statistical distribution of the porosity. Due to the peculiarity of the cell morphology (e.g. single larger cells), stress-strain localization has been demonstrated as one of the reasons of the scattering found during the experiments. A material model, to reproduce the investigated foam mechanical behavior, has been calibrated. Despite the difference among experiments the material model is able to reproduce all of them. Difference between the model coefficients quantifies roughly the difference due to the local geometry of the cells
Current status of the CLIO project
CLIO (Cryogenic Laser Interferometer Observatory) is a Japanese gravitational
wave detector project. One of the main purposes of CLIO is to demonstrate
thermal-noise suppression by cooling mirrors for a future Japanese project,
LCGT (Large-scale Cryogenic Gravitational Telescope). The CLIO site is in
Kamioka mine, as is LCGT. The progress of CLIO between 2005 and 2007 (room- and
cryogenic-temperature experiments) is introduced in this article. In a
room-temperature experiment, we made efforts to improve the sensitivity. The
current best sensitivity at 300 K is about
around 400 Hz. Below 20 Hz, the strain (not displacement) sensitivity is
comparable to that of LIGO, although the baselines of CLIO are 40-times shorter
(CLIO: 100m, LIGO: 4km). This is because seismic noise is extremely small in
Kamioka mine. We operated the interferometer at room temperature for
gravitational wave observations. We obtained 86 hours of data. In the cryogenic
experiment, it was confirmed that the mirrors were sufficiently cooled (14 K).
However, we found that the radiation shield ducts transferred 300K radiation
into the cryostat more effectively than we had expected. We observed that noise
caused by pure aluminum wires to suspend a mirror was suppressed by cooling the
mirror.Comment: 8 pages, 9 figures. Amaldi7 proceedings, J. Phys.: Conf. Ser.
(accepted
Sets computing the symmetric tensor rank
Let n_d denote the degree d Veronese embedding of a projective space P^r. For
any symmetric tensor P, the 'symmetric tensor rank' sr(P) is the minimal
cardinality of a subset A of P^r, such that n_d(A) spans P. Let S(P) be the
space of all subsets A of P^r, such that n_d(A) computes sr(P). Here we
classify all P in P^n such that sr(P) < 3d/2 and sr(P) is computed by at least
two subsets. For such tensors P, we prove that S(P) has no isolated points
Comparison of advanced gravitational-wave detectors
We compare two advanced designs for gravitational-wave antennas in terms of
their ability to detect two possible gravitational wave sources. Spherical,
resonant mass antennas and interferometers incorporating resonant sideband
extraction (RSE) were modeled using experimentally measurable parameters. The
signal-to-noise ratio of each detector for a binary neutron star system and a
rapidly rotating stellar core were calculated. For a range of plausible
parameters we found that the advanced LIGO interferometer incorporating RSE
gave higher signal-to-noise ratios than a spherical detector resonant at the
same frequency for both sources. Spheres were found to be sensitive to these
sources at distances beyond our galaxy. Interferometers were sensitive to these
sources at far enough distances that several events per year would be expected
- …