687 research outputs found
Stable Marriage with Multi-Modal Preferences
We introduce a generalized version of the famous Stable Marriage problem, now
based on multi-modal preference lists. The central twist herein is to allow
each agent to rank its potentially matching counterparts based on more than one
"evaluation mode" (e.g., more than one criterion); thus, each agent is equipped
with multiple preference lists, each ranking the counterparts in a possibly
different way. We introduce and study three natural concepts of stability,
investigate their mutual relations and focus on computational complexity
aspects with respect to computing stable matchings in these new scenarios.
Mostly encountering computational hardness (NP-hardness), we can also spot few
islands of tractability and make a surprising connection to the \textsc{Graph
Isomorphism} problem
Modelling the relative velocities of isolated pairs of galaxies
We study the comoving relative velocities, v12, of model isolated galaxy
pairs at z=0.5. For this purpose, we use the predictions from the GALFORM
semi-analytical model of galaxy formation and evolution based on a Lambda cold
dark matter cosmology consistent with the results from WMAP7. In real space, we
find that isolated pairs of galaxies are predicted to form an angle t with the
line-of-sight that is uniformily distributed as expected if the Universe is
homogeneous and isotropic. We also find that isolated pairs of galaxies
separated by a comoving distance between 1 and 3 Mpc/h are predicted to have
=0. For galaxies in this regime, the distribution of the angle t is
predicted to change minimally from real to redshift space, with a change
smaller than 5% in . However, the distances defining the comoving
regime strongly depends on the applied isolation criteria.Comment: 4 pages, 4 figures, SF2A 2013 Proceedin
The Travel Industry: What\u27s in a Name?
The travel and tourism industry is enormous in both size and importance. There can be little doubt that the field is striving to accommodate the diversity of opinion concerning what the industry is and how it can be improved and enlarged even further. Resistance to critiquing long-held beliefs about the industry may inhibit its future. Deconstruction, a postmodern method of analysis, is proposed as one tool with which to engage in reflection upon what the industry is and where it may be headed
Jackknife resampling technique on mocks: an alternative method for covariance matrix estimation
We present a fast and robust alternative method to compute covariance matrix
in case of cosmology studies. Our method is based on the jackknife resampling
applied on simulation mock catalogues. Using a set of 600 BOSS DR11 mock
catalogues as a reference, we find that the jackknife technique gives a similar
galaxy clustering covariance matrix estimate by requiring a smaller number of
mocks. A comparison of convergence rates show that 7 times fewer
simulations are needed to get a similar accuracy on variance. We expect this
technique to be applied in any analysis where the number of available N-body
simulations is low.Comment: 11 pages, 11 figures, 2 table
Approximability of Connected Factors
Finding a d-regular spanning subgraph (or d-factor) of a graph is easy by
Tutte's reduction to the matching problem. By the same reduction, it is easy to
find a minimal or maximal d-factor of a graph. However, if we require that the
d-factor is connected, these problems become NP-hard - finding a minimal
connected 2-factor is just the traveling salesman problem (TSP).
Given a complete graph with edge weights that satisfy the triangle
inequality, we consider the problem of finding a minimal connected -factor.
We give a 3-approximation for all and improve this to an
(r+1)-approximation for even d, where r is the approximation ratio of the TSP.
This yields a 2.5-approximation for even d. The same algorithm yields an
(r+1)-approximation for the directed version of the problem, where r is the
approximation ratio of the asymmetric TSP. We also show that none of these
minimization problems can be approximated better than the corresponding TSP.
Finally, for the decision problem of deciding whether a given graph contains
a connected d-factor, we extend known hardness results.Comment: To appear in the proceedings of WAOA 201
Search for neutrinos from transient sources with the ANTARES telescope and optical follow-up observations
The ANTARES telescope has the opportunity to detect transient neutrino
sources, such as gamma-ray bursts, core-collapse supernovae, flares of active
nuclei... To enhance the sensitivity to these sources, we have developed a new
detection method based on the optical follow-up of "golden" neutrino events
such as neutrino doublets coincident in time and space or single neutrinos of
very high energy. The ANTARES Collaboration has therefore implemented a very
fast on-line reconstruction with a good angular resolution. These
characteristics allow to trigger an optical telescope network; since February
2009. ANTARES is sending alert trigger one or two times per month to the two 25
cm robotic telescope of TAROT. This follow-up of such special events would not
only give access to the nature of the sources but also improves the sensitivity
for transient neutrino sources.Comment: 3 pages, 3 figures, Proceedings of the 31st ICRC, Lodz, Polan, July
200
Microbiological aspects of methane emission in a ricefield soil from the Camargue (France) : 2. Methanotrophy and related microflora
Les principaux facteurs qui influencent l'activité méthanotrophe du sol (épaisseur du sol, humidité, addition d'engrais et dessiccation) ont été étudiés in vitro sur un sol de rizière de Camargue (France) afin de standardiser une méthode pour estimer l'activité méthanotrophe potentielle (PMA) d'un sol. La possibilité d'énumérer les méthanotrophes du sol a été étudiée et les souches dominantes du sol incubé pendant un mois sous un mélange de 80% air/20% CH4 ont été isolées. La méthanotrophie in vitro est un phénomène quantifiable par unité de surface plutôt que par unité de poids de sol. L'activité maximale (PMA)(1.8 mole m-2 j-1) a été mesurée sur un échantillon à une humidité voisine de la capacité au champ et incubé pendant un mois sous air/CH4. Les consommations de CH4 et d'O2 ainsi que la production de CO2 sont fortement corrélées. La consommation d'O2 liée à l'activité hétérotrophe du sol est négligeable comparée à celle due à l'activité méthanotrophe. L'addition d'engrais à des concentrations utilisées en agriculture est sans effet sur la PMA qui est restée stable pendant deux ans dans le sol conservé à l'état sec. Une très forte contamination rend les étalements sur boites de Pétri inexploitables pour dénombrer les bactéries méthanotrophes du sol. Les populations estimées par MPN sont faibles dans le sol sec (2.5 x 102 g-1) et atteignent 5 x 108 g-1 dans le sol enrichi. La morphologie des souches isolées indique leur appartenance aux bactéries méthanotrophes de type II. (Résumé d'auteur
Integer Quantum Hall Effect in Trilayer Graphene
The Integer Quantum Hall Effect (IQHE) is a distinctive phase of
two-dimensional electronic systems subjected to a perpendicular magnetic field.
Thus far, the IQHE has been observed in semiconductor heterostructures and in
mono- and bi-layer graphene. Here we report on the IQHE in a new system:
trilayer graphene. Experimental data are compared with self-consistent Hartree
calculations of the Landau levels for the gated trilayer. The plateau structure
in the Hall resistivity determines the stacking order (ABA versus ABC). We find
that the IQHE in ABC trilayer graphene is similar to that in the monolayer,
except for the absence of a plateau at filling factor v=2. At very low filling
factor, the Hall resistance vanishes due to the presence of mixed electron and
hole carriers induced by disorder.Comment: 5 pages, 4 figure
Beyond physical entrainment: Competitive and cooperative mental stances during identical joint-action tasks differently affect inter-subjective neural synchrony and judgments of agency
10.1080/17470919.2020.1727949Social Neuroscience1503368-37
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