4,411 research outputs found
Mapping road network communities for guiding disease surveillance and control strategies
Human mobility is increasing in its volume, speed and reach, leading to the
movement and introduction of pathogens through infected travelers. An
understanding of how areas are connected, the strength of these connections and
how this translates into disease spread is valuable for planning surveillance
and designing control and elimination strategies. While analyses have been
undertaken to identify and map connectivity in global air, shipping and
migration networks, such analyses have yet to be undertaken on the road
networks that carry the vast majority of travellers in low and middle income
settings. Here we present methods for identifying road connectivity
communities, as well as mapping bridge areas between communities and key
linkage routes. We apply these to Africa, and show how many highly-connected
communities straddle national borders and when integrating malaria prevalence
and population data as an example, the communities change, highlighting regions
most strongly connected to areas of high burden. The approaches and results
presented provide a flexible tool for supporting the design of disease
surveillance and control strategies through mapping areas of high connectivity
that form coherent units of intervention and key link routes between
communities for targeting surveillance.Comment: 11 pages, 5 figures, research pape
Effective transport barriers in nontwist systems
In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. These barriers have been identified in symplectic nontwist maps that model such zonal flows. We use the so-called standard nontwist map, a paradigmatic example of nontwist systems, to analyze the parameter dependence of the transport through a broken shearless barrier. On varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Moreover, we show how these stickiness structures, and the concomitant transport reduction in the shearless region, are determined by a homoclinic tangle of the remaining dominant twin island chains. We use the finite-time rotation number, a recently proposed diagnostic, to identify transport barriers that separate different regions of stickiness. The identified barriers are comparable to those obtained by using finite-time Lyapunov exponents.FAPESPCNPqCAPESMCT/CNEN (Rede Nacional de Fusao)Fundacao AraucariaUS Department of Energy DE-FG05-80ET-53088Physic
WKB Wave Functions with the Induced Gravity Theory
The Wheeler-DeWitt equation for the induced gravity theory is constructed in
the minisuperspace approximation, and then solved using the WKB method under
three types of boundary condition proposed respectively by Hartle & Hawking
(``no boundary''), Linde and Vilenkin (``tunneling from nothing''). It is found
that no matter how the gravitational and cosmological ``constants'' vary in the
classical models, they will acquire constant values when the universe comes
from quantum creation, and that, in particular, the resulting tunneling wave
function under the Linde or Vilenkin boundary condition reaches its maximum
value if the cosmological constant vanishes.Comment: 10 pages, no figure, LaTex fil
Ocorrência e controle de pragas na cultura do sorgo no Sudoeste de Goiás safrinha.
bitstream/CNPMS/17601/1/Circ_50.pd
Constraints on Cosmological Parameters from Future Galaxy Cluster Surveys
We study the expected redshift evolution of galaxy cluster abundance between
0 < z < 3 in different cosmologies, including the effects of the cosmic
equation of state parameter w=p/rho. Using the halo mass function obtained in
recent large scale numerical simulations, we model the expected cluster yields
in a 12 deg^2 Sunyaev-Zeldovich Effect (SZE) survey and a deep 10^4 deg^2 X-ray
survey over a wide range of cosmological parameters. We quantify the
statistical differences among cosmologies using both the total number and
redshift distribution of clusters. Provided that the local cluster abundance is
known to a few percent accuracy, we find only mild degeneracies between w and
either Omega_m or h. As a result, both surveys will provide improved
constraints on Omega_m and w. The Omega_m-w degeneracy from both surveys is
complementary to those found either in studies of CMB anisotropies or of
high-redshift Supernovae (SNe). As a result, combining these surveys together
with either CMB or SNe studies can reduce the statistical uncertainty on both w
and Omega_m to levels below what could be obtained by combining only the latter
two data sets. Our results indicate a formal statistical uncertainty of about
3% (68% confidence) on both Omega_m and w when the SZE survey is combined with
either the CMB or SN data; the large number of clusters in the X-ray survey
further suppresses the degeneracy between w and both Omega_m and h. Systematics
and internal evolution of cluster structure at the present pose uncertainties
above these levels. We briefly discuss and quantify the relevant systematic
errors. By focusing on clusters with measured temperatures in the X-ray survey,
we reduce our sensitivity to systematics such as non-standard evolution of
internal cluster structure.Comment: ApJ, revised version. Expanded discussion of systematics;
Press-Schechter mass function replaced by fit from simulation
Weak Lensing as a Calibrator of the Cluster Mass-Temperature Relation
The abundance of clusters at the present epoch and weak gravitational lensing
shear both constrain roughly the same combination of the power spectrum
normalization sigma_8 and matter energy density Omega_M. The cluster constraint
further depends on the normalization of the mass-temperature relation.
Therefore, combining the weak lensing and cluster abundance data can be used to
accurately calibrate the mass-temperature relation. We discuss this approach
and illustrate it using data from recent surveys.Comment: Matches the version in ApJL. Equation 4 corrected. Improvements in
the analysis move the cluster contours in Fig1 slightly upwards. No changes
in the conclusion
Mass-Temperature Relation of Galaxy Clusters: A Theoretical Study
Combining conservation of energy throughout nearly-spherical collapse of
galaxy clusters with the virial theorem, we derive the mass-temperature
relation for X-ray clusters of galaxies . The normalization factor
and the scatter of the relation are determined from first principles with
the additional assumption of initial Gaussian random field. We are also able to
reproduce the recently observed break in the M-T relation at T \sim 3 \keV,
based on the scatter in the underlying density field for a low density
CDM cosmology. Finally, by combining observational data of high
redshift clusters with our theoretical formalism, we find a semi-empirical
temperature-mass relation which is expected to hold at redshifts up to unity
with less than 20% error.Comment: 43 pages, 13 figures, One figure is added and minor changes are made.
Accepted for Publication in Ap
Smart operational load monitoring using decision trees and artificial neural networks: a comparative study
Operational Load Monitoring is an industrial process that allows to predict the remaining in-service life of a mechanical structure under variable loads. Data from sensors embedded or mounted on the structure is acquired and allows to estimate the number and amplitude of load cycles that the structure has withstood so far in its working environment. This process is especially important in the aerospace industry where mechanical structures of an aircraft are monitored in order to maximize their operating lifetime. Smart Operational Load Monitoring means implementation of artificial intelligence techniques to the process in order to make predictions based on measurements from reduced number of sensors. In this paper a composite lightweight structure of typical geometry used in aircraft structures is taken as an example for Smart Operational Load Monitoring. The predictions are made from measurements from six strain gauges mounted to the structure, using carefully prepared artificial intelligence-based models. Efficiency of the models is compared, in terms of their prediction accuracies and computational complexities.National Agency for Academic Exchange of PolandSilesian University of Technology. Faculty of Mechanical Engineerin
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