44,672 research outputs found
An n-sided polygonal model to calculate the impact of cyber security events
This paper presents a model to represent graphically the impact of cyber
events (e.g., attacks, countermeasures) in a polygonal systems of n-sides. The
approach considers information about all entities composing an information
system (e.g., users, IP addresses, communication protocols, physical and
logical resources, etc.). Every axis is composed of entities that contribute to
the execution of the security event. Each entity has an associated weighting
factor that measures its contribution using a multi-criteria methodology named
CARVER. The graphical representation of cyber events is depicted as straight
lines (one dimension) or polygons (two or more dimensions). Geometrical
operations are used to compute the size (i.e, length, perimeter, surface area)
and thus the impact of each event. As a result, it is possible to identify and
compare the magnitude of cyber events. A case study with multiple security
events is presented as an illustration on how the model is built and computed.Comment: 16 pages, 5 figures, 2 tables, 11th International Conference on Risks
and Security of Internet and Systems, (CRiSIS 2016), Roscoff, France,
September 201
On the stratified dust distribution of the GG Tau circumbinary ring
Our objective is to study the vertical dust distribution in the circumbinary
ring of the binary system GG Tau and to search for evidence of stratification,
one of the first steps expected to occur during planet formation.
We present a simultaneous analysis of four scattered light images spanning a
range of wavelength from 800 nm to 3800 nm and compare them with (i) a
parametric prescription for the vertical dust stratification, and (ii) with the
results of SPH bi-fluid hydrodynamic calculations.
The parametric prescription and hydrodynamical calculations of stratification
both reproduce the observed brightness profiles well. These models also provide
a correct match for the observed star/ring integrated flux ratio. Another
solution with a well-mixed, but ``exotic'', dust size distribution also matches
the brightness profile ratios but fails to match the star/ring flux ratio.
These results give support to the presence of vertical stratification of the
dust in the ring of GG Tau and further predict the presence of a radial
stratification also.Comment: 9 pages, 11 figures. Accepted for publication in A&
A new bridge between leptonic CP violation and leptogenesis
Flavor effects due to lepton interactions in the early Universe may have
played an important role in the generation of the cosmological baryon asymmetry
through leptogenesis. If the only source of high-energy CP violation comes from
the left-handed leptonic sector, then it is possible to establish a bridge
between flavored leptogenesis and low-energy leptonic CP violation. We explore
this connection taking into account our present knowledge about low-energy
neutrino parameters and the matter-antimatter asymmetry observed in the
Universe. In this framework, we find that leptogenesis favors a hierarchical
light neutrino mass spectrum, while for quasi-degenerate and inverted
hierarchical neutrino masses there is a very narrow allowed window. The
absolute neutrino mass scale turns out to be m < 0.1 eV.Comment: 10 pages, 3 figure
N electrons in a quantum dot: Two-point Pade approximants
We present analytic estimates for the energy levels of N electrons (N = 2 -
5) in a two-dimensional parabolic quantum dot. A magnetic field is applied
perpendicularly to the confinement plane. The relevant scaled energy is shown
to be a smooth function of the parameter \beta=(effective Rydberg/effective dot
energy)^{1/6}. Two-point Pade approximants are obtained from the series
expansions of the energy near the oscillator () and Wigner
() limits. The approximants are expected to work with an error
not greater than 2.5% in the entire interval .Comment: 27 pages. LaTeX. 6 figures not include
The accumulation and trapping of grains at planet gaps: effects of grain growth and fragmentation
We model the dust evolution in protoplanetary disks with full 3D, Smoothed
Particle Hydrodynamics (SPH), two-phase (gas+dust) hydrodynamical simulations.
The gas+dust dynamics, where aerodynamic drag leads to the vertical settling
and radial migration of grains, is consistently treated. In a previous work, we
characterized the spatial distribution of non-growing dust grains of different
sizes in a disk containing a gap-opening planet and investigated the gap's
detectability with the Atacama Large Millimeter/submillimeter Array (ALMA).
Here we take into account the effects of grain growth and fragmentation and
study their impact on the distribution of solids in the disk. We show that
rapid grain growth in the two accumulation zones around planet gaps is strongly
affected by fragmentation. We discuss the consequences for ALMA observations.Comment: Accepted for publication in Planetary and Space Science. 13 pages, 4
figure
Astrophysical and Cosmological Information from Large-scale sub-mm Surveys of Extragalactic Sources
We present a quantitative analysis of the astrophysical and cosmological
information that can be extracted from the many important wide-area, shallow
surveys that will be carried out in the next few years. Our calculations
combine the predictions of the physical model by Granato et al. (2004) for the
formation and evolution of spheroidal galaxies with up-to-date phenomenological
models for the evolution of starburst and normal late-type galaxies and of
radio sources. We compute the expected number counts and the redshift
distributions of these source populations separately and then focus on
proto-spheroidal galaxies. For the latter objects we predict the counts and
redshift distributions of strongly lensed sources at 250, 350, 500, and 850
micron, the angular correlation function of sources detected in the surveys
considered, the angular power spectra due to clustering of sources below the
detection limit in Herschel and Planck surveys. An optimal survey for selecting
strongly lensed proto-spheroidal galaxies is described, and it is shown how
they can be easily distinguished from the other source populations. We also
discuss the detectability of the imprints of the 1-halo and 2-halo regimes on
angular correlation functions and clustering power spectra, as well as the
constraints on cosmological parameters that can be obtained from the
determinations of these quantities. The novel data relevant to derive the first
sub-millimeter estimates of the local luminosity functions of starburst and
late-type galaxies, and the constraints on the properties of rare source
populations, such as blazars, are also briefly described.Comment: 16 pages, 10 figures. Accepted for publication on MNRA
Spontaneous leptonic CP violation and nonzero
We consider a simple extension of the Standard Model by adding two Higgs
triplets and a complex scalar singlet to its particle content. In this
framework, the CP symmetry is spontaneously broken at high energies by the
complex vacuum expectation value of the scalar singlet. Such a breaking leads
to leptonic CP violation at low energies. The model also exhibits an flavour symmetry which, after being spontaneously broken at a high-energy
scale, yields a tribimaximal pattern in the lepton sector. We consider small
perturbations around the tribimaximal vacuum alignment condition in order to
generate nonzero values of , as required by the latest neutrino
oscillation data. It is shown that the value of recently measured
by the Daya Bay Reactor Neutrino Experiment can be accommodated in our
framework together with large Dirac-type CP violation. We also address the
viability of leptogenesis in our model through the out-of-equilibrium decays of
the Higgs triplets. In particular, the CP asymmetries in the triplet decays
into two leptons are computed and it is shown that the effective leptogenesis
and low-energy CP-violating phases are directly linked.Comment: 17 pages; 6 figures; references added and typos corrected. Final
version to appear in PR
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