2,313 research outputs found
New neighborhood based rough sets
Neighborhood based rough sets are important generalizations of the classical rough sets of Pawlak, as neighborhood operators generalize equivalence classes. In this article, we introduce nine neighborhood based operators and we study the partial order relations between twenty-two different neighborhood operators obtained from one covering. Seven neighborhood operators result in new rough set approximation operators. We study how these operators are related to the other fifteen neighborhood based approximation operators in terms of partial order relations, as well as to seven non-neighborhood-based rough set approximation operators
Predicting criticality and dynamic range in complex networks: effects of topology
The collective dynamics of a network of coupled excitable systems in response
to an external stimulus depends on the topology of the connections in the
network. Here we develop a general theoretical approach to study the effects of
network topology on dynamic range, which quantifies the range of stimulus
intensities resulting in distinguishable network responses. We find that the
largest eigenvalue of the weighted network adjacency matrix governs the network
dynamic range. Specifically, a largest eigenvalue equal to one corresponds to a
critical regime with maximum dynamic range. We gain deeper insight on the
effects of network topology using a nonlinear analysis in terms of additional
spectral properties of the adjacency matrix. We find that homogeneous networks
can reach a higher dynamic range than those with heterogeneous topology. Our
analysis, confirmed by numerical simulations, generalizes previous studies in
terms of the largest eigenvalue of the adjacency matrix.Comment: 4 pages, 3 figure
Statistical Properties of Avalanches in Networks
We characterize the distributions of size and duration of avalanches
propagating in complex networks. By an avalanche we mean the sequence of events
initiated by the externally stimulated `excitation' of a network node, which
may, with some probability, then stimulate subsequent firings of the nodes to
which it is connected, resulting in a cascade of firings. This type of process
is relevant to a wide variety of situations, including neuroscience, cascading
failures on electrical power grids, and epidemology. We find that the
statistics of avalanches can be characterized in terms of the largest
eigenvalue and corresponding eigenvector of an appropriate adjacency matrix
which encodes the structure of the network. By using mean-field analyses,
previous studies of avalanches in networks have not considered the effect of
network structure on the distribution of size and duration of avalanches. Our
results apply to individual networks (rather than network ensembles) and
provide expressions for the distributions of size and duration of avalanches
starting at particular nodes in the network. These findings might find
application in the analysis of branching processes in networks, such as
cascading power grid failures and critical brain dynamics. In particular, our
results show that some experimental signatures of critical brain dynamics
(i.e., power-law distributions of size and duration of neuronal avalanches),
are robust to complex underlying network topologies.Comment: 11 pages, 7 figure
Leptonic Charged Higgs Decays in the Zee Model
We consider the version of the Zee model where both Higgs doublets couple to
leptons. Within this framework we study charged Higgs decays. We focus on a
model with minimal number of parameters consistent with experimental neutrino
data. Using constraints from neutrino physics we (i) discuss the reconstruction
of the parameter space of the model using the leptonic decay patterns of both
of the two charged Higgses, , and the decay
of the heavier charged Higgs, ; (ii) show that the
decay rate in general is enhanced in
comparision to the standard two Higgs doublet model while in some regions of
parameter space even dominates over
.Comment: 25 pages, 9 figure
Probing neutrino mass with multilepton production at the Tevatron in the simplest R-parity violation model
We analyze the production of multileptons in the simplest supergravity model
with bilinear violation of R parity at the Fermilab Tevatron. Despite the small
R-parity violating couplings needed to generate the neutrino masses indicated
by current atmospheric neutrino data, the lightest supersymmetric particle is
unstable and can decay inside the detector. This leads to a phenomenology quite
distinct from that of the R-parity conserving scenario. We quantify by how much
the supersymmetric multilepton signals differ from the R-parity conserving
expectations, displaying our results in the plane. We
show that the presence of bilinear R-parity violating interactions enhances the
supersymmetric multilepton signals over most of the parameter space, specially
at moderate and large .Comment: 26 pages, 23 figures. Revised version with some results corrected and
references added. Conclusions remain the sam
An efficient and robust procedure to calculate absorption spectra of aqueous charged species applied to NO2â
Accurate calculation of absorption spectra of aqueous NO2ârequires rigorously sampling the quantum potential energy surfaces for microsolvation of NO2âwith at least five explicit water molecules and embedding the resulting clusters in a continuum solvent accounting for the statistical weighted contributions of individual isomers. This method, which we address as ASCEC + PCM, introduces several desired features when compared against MD simulations derived QM/MM spectra: comparatively fewer explicit solvent molecules to be treated with expensive QM methods, the identification of equilibrium structures in the quantum PES to be used in further vibrational spectroscopy, and the unequivocal identification of cluster orbitals undergoing electronic transitions and charge transfer that originate the spectral bands
Ring Vibrations to Sense Anionic Ibuprofen in Aqueous Solution as Revealed by Resonance Raman
We unravel the potentialities of resonance Raman spectroscopy to detect ibuprofen in diluted aqueous solutions. In particular, we exploit a fully polarizable quantum mechanics/molecular mechanics (QM/MM) methodology based on fluctuating charges coupled to molecular dynamics (MD) in order to take into account the dynamical aspects of the solvation phenomenon. Our findings, which are discussed in light of a natural bond orbital (NBO) analysis, reveal that a selective enhancement of the Raman signal due to the normal mode associated with the CâC stretching in the ring, ÎœC=C, can be achieved by properly tuning the incident wavelength, thus facilitating the recognition of ibuprofen in water samples
A model for microinstability destabilization and enhanced transport in the presence of shielded 3-D magnetic perturbations
A mechanism is presented that suggests shielded 3-D magnetic perturbations
can destabilize microinstabilities and enhance the associated anomalous
transport. Using local 3-D equilibrium theory, shaped tokamak equilibria with
small 3-D deformations are constructed. In the vicinity of rational magnetic
surfaces, the infinite-n ideal MHD ballooning stability boundary is strongly
perturbed by the 3-D modulations of the local magnetic shear associated with
the presence of nearresonant Pfirsch-Schluter currents. These currents are
driven by 3-D components of the magnetic field spectrum even when there is no
resonant radial component. The infinite-n ideal ballooning stability boundary
is often used as a proxy for the onset of virulent kinetic ballooning modes
(KBM) and associated stiff transport. These results suggest that the achievable
pressure gradient may be lowered in the vicinity of low order rational surfaces
when 3-D magnetic perturbations are applied. This mechanism may provide an
explanation for the observed reduction in the peak pressure gradient at the top
of the edge pedestal during experiments where edge localized modes have been
completely suppressed by applied 3-D magnetic fields
ShalĂŽm y Berakah don gratuito de yhwh el texto sacerdotal de Nm 6, 22-27
The priestly blessing in Numbers 6, 22-27 encloses a beautiful piece of the Pentateuch. It contains not only a beautiful expression but also an esthetic narrative and its lyrics are still valid today in the Jewish and Christian liturgies. This essay looks over again into the Old Testament sources to discover new features of celebration and faith still in force for the community of believers.La bendiciĂłn sacerdotal de NĂșmeros 6,22-27 contiene dentro del conjunto de la Torah hebrea, un fragmento sublime del Pentateuco. No solo se destaca en el pasaje su belleza expresiva, sino tambiĂ©n su estĂ©tica narrativa y su lĂrica vigente aĂșn en la liturgia judĂa y cristiana. Por ello el recurso a las fuentes, incluido el Antiguo Testamento, podrĂĄ vislumbrar rasgos de la celebraciĂłn y la vivencia de la fe, todavĂa actuales para una comunidad creyente
Associative Cortex Features in the First Olfactory Brain Relay Station
SummarySynchronized firing of mitral cells (MCs) in the olfactory bulb (OB) has been hypothesized to help bind information together in olfactory cortex (OC). In this survey of synchronized firing by suspected MCs in awake, behaving vertebrates, we find the surprising result that synchronized firing conveys information on odor value (âIs it rewarded?â) rather than odor identity (âWhat is the odor?â). We observed that as mice learned to discriminate between odors, synchronous firing responses to the rewarded and unrewarded odors became divergent. Furthermore, adrenergic blockage decreases the magnitude of odor divergence of synchronous trains, suggesting that MCs contribute to decision-making through adrenergic-modulated synchronized firing. Thus, in the olfactory system information on stimulus reward is found in MCs one synapse away from the sensory neuron
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