4,074 research outputs found
Dimensionality of social networks using motifs and eigenvalues
We consider the dimensionality of social networks, and develop experiments
aimed at predicting that dimension. We find that a social network model with
nodes and links sampled from an -dimensional metric space with power-law
distributed influence regions best fits samples from real-world networks when
scales logarithmically with the number of nodes of the network. This
supports a logarithmic dimension hypothesis, and we provide evidence with two
different social networks, Facebook and LinkedIn. Further, we employ two
different methods for confirming the hypothesis: the first uses the
distribution of motif counts, and the second exploits the eigenvalue
distribution.Comment: 26 page
Comportamento de genótipos de soja em relação a acidez do solo.
bitstream/item/133644/1/ID10195-1992-1993sojaresultados-p122-129.pdfTrabalho apresentado na XXI Reunião de Pesquisa de Soja da Região Sul, Santa Rosa, 1993
NP-Completeness Results for Graph Burning on Geometric Graphs
Graph burning runs on discrete time steps. The aim is to burn all the
vertices in a given graph in the least number of time steps. This number is
known to be the burning number of the graph. The spread of social influence, an
alarm, or a social contagion can be modeled using graph burning. The less the
burning number, the faster the spread.
Optimal burning of general graphs is NP-Hard. There is a 3-approximation
algorithm to burn general graphs where as better approximation factors are
there for many sub classes. Here we study burning of grids; provide a lower
bound for burning arbitrary grids and a 2-approximation algorithm for burning
square grids. On the other hand, burning path forests, spider graphs, and trees
with maximum degree three is already known to be NP-Complete. In this article
we show burning problem to be NP-Complete on connected interval graphs,
permutation graphs and several other geometric graph classes as corollaries.Comment: 17 pages, 5 figure
CNOT and Bell-state analysis in the weak-coupling cavity QED regime
We propose an interface between the spin of a photon and the spin of an
electron confined in a quantum dot embedded in a microcavity operating in the
weak coupling regime. This interface, based on spin selective photon reflection
from the cavity, can be used to construct a CNOT gate, a multi-photon entangler
and a photonic Bell-state analyzer. Finally, we analyze experimental
feasibility, concluding that the schemes can be implemented with current
technology.Comment: 4 pages, 2 figure
Atomically-thin quantum dots integrated with lithium niobate photonic chips
The electro-optic, acousto-optic and nonlinear properties of lithium niobate
make it a highly versatile material platform for integrated quantum photonic
circuits. A prerequisite for quantum technology applications is the ability to
efficiently integrate single photon sources, and to guide the generated photons
through ad-hoc circuits. Here we report the integration of quantum dots in
monolayer WSe2 into a Ti in-diffused lithium niobate directional coupler. We
investigate the coupling of individual quantum dots to the waveguide mode,
their spatial overlap, and the overall efficiency of the hybrid-integrated
photonic circuit
H1 photonic crystal cavitites for hybrid quantum information protocols
Hybrid quantum information protocols are based on local qubits, such as
trapped atoms, NV centers, and quantum dots, coupled to photons. The coupling
is achieved through optical cavities. Here we demonstrate far-field optimized
H1 photonic crystal membrane cavities combined with an additional back
reflection mirror below the membrane that meet the optical requirements for
implementing hybrid quantum information protocols. Using numerical optimization
we find that 80% of the light can be radiated within an objective numerical
aperture of 0.8, and the coupling to a single-mode fiber can be as high as 92%.
We experimentally prove the unique external mode matching properties by
resonant reflection spectroscopy with a cavity mode visibility above 50%.Comment: 14 pages, 11 figure
Otimização do método de extração de DNA de Magnaporthe oryzae de trigo.
bitstream/item/114990/1/2014-Comunicado-tecnico-online-343.pd
Fast Two-Robot Disk Evacuation with Wireless Communication
In the fast evacuation problem, we study the path planning problem for two
robots who want to minimize the worst-case evacuation time on the unit disk.
The robots are initially placed at the center of the disk. In order to
evacuate, they need to reach an unknown point, the exit, on the boundary of the
disk. Once one of the robots finds the exit, it will instantaneously notify the
other agent, who will make a beeline to it.
The problem has been studied for robots with the same speed~\cite{s1}. We
study a more general case where one robot has speed and the other has speed
. We provide optimal evacuation strategies in the case that by showing matching upper and lower bounds on the
worst-case evacuation time. For , we show (non-matching)
upper and lower bounds on the evacuation time with a ratio less than .
Moreover, we demonstrate that a generalization of the two-robot search strategy
from~\cite{s1} is outperformed by our proposed strategies for any .Comment: 18 pages, 10 figure
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