5,284 research outputs found
Weaving a fabric of socially aware agents
The expansion of web-enabled social interaction has shed light on social aspects of intelligence that have not been typically studied within the AI paradigm so far. In this context, our aim is to understand what constitutes intelligent social behaviour and to build computational systems that support it. We argue that social intelligence involves socially aware, autonomous individuals that agree on how to accomplish a common endeavour, and then enact such agreements. In particular, we provide a framework with the essential elements for such agreements to be achieved and executed by individuals that meet in an open environment. Such framework sets the foundations to build a computational infrastructure that enables socially aware autonomy.This work has been supported by the projects EVE(TIN2009-14702-C02-01) and AT (CSD2007-0022)Peer Reviewe
Inverse design and experimental realization of plasma metamaterials
We apply inverse design methods to produce two-dimensional triangular-lattice
plasma metamaterial (PMM) devices which are then constructed and demonstrated
experimentally. Finite difference frequency domain simulations are used along
with forward-mode automatic differentiation to optimize the plasma densities of
each of the plasma elements in the PMM to perform beam steering and
demultiplexing under transverse magnetic polarization. The optimal device
parameters are then used to assign plasma density values to elements that make
up an experimental version of the device. Device performance is evaluated
against both the simulated results and human-designed alternatives, showing the
benefits and disadvantages of in-silico inverse design and paving the way for
future fully in-situ optimization.Comment: 22 pages, 8 figures; submitted to Phys. Rev. Applie
Inverse design of plasma metamaterial devices with realistic elements
In an expansion of a previous study [1], we apply inverse design methods to
produce two-dimensional plasma metamaterial devices with realistic plasma
elements which incorporate quartz envelopes, collisionality (loss), non-uniform
density profiles, and resistance to experimental error/perturbation.
Backpropagated finite difference frequency domain simulations are used to
design waveguides and demultiplexers operating under the transverse magnetic
polarization. Optimal devices with realistic elements are compared to previous
devices with idealized elements, and several parameter initialization schemes
for the optimization algorithm are explored. Demultiplexing and waveguiding are
demonstrated for microwave-regime devices composed of plasma elements with
reasonable space-averaged plasma frequencies ~10 GHz and a collision frequency
~1 GHz, allowing for future in-situ training and experimental realization of
these designs.Comment: 9 pages, 9 figure
Measurement bias in the HICP: what do we know, and what do we need to know?
The Harmonized Index Of Consumer Prices (HICP) is the primary measure of inflation in the euro area, and plays a central role in the policy deliberations of the European Central Bank (ECB). Among the rationales given for defining price stability as prevailing at some positive measured inflation rate is the possibility that the HICP as published incorporates measurement errors of one sort or another that may cause it to systematically overstate the true rate of inflation in the euro area. The purpose of this paper is to review what is known about the scope of measurement error in the HICP. We conclude that given the scant research on price measurement issues in the EU and the ongoing improvements in the HICP, there is almost no scientific basis at this time for a point (or even an interval) estimate of a positive bias in the HICP. JEL Classification: C43, E31Harmonized Index of Consumer Prices, HICP, measurement error
The Impact of Soil Disturbance on Soil Bacterial Community Composition
Soil bacterial communities are an important part of terrestrial ecosystems due to their roles in biogeochemical cycling processes. Consequently, understanding how soil disturbance affects the soil bacterial diversity is vital to understanding the entire ecosystem. In this study we examined the effects of soil disturbance (by mining) on the soil bacterial community composition from three sites on Bauxite Ridge in Southeast Tennessee compared to three undisturbed sites in a nearby location. The soil bacterial community was analyzed by 16S rDNA amplicon sequencing of total DNA extracted from the soil samples collected from each of the six sites. Characterization of the bacterial community of these six sites showed that soil disturbance does not appear to be correlated with the differences in the diversity of the bacterial community, though this does not correlate with previous research
Magnetic-crystallographic phase diagram of superconducting parent compound FeTe
hrough neutron diffraction experiments, including spin-polarized
measurements, we find a collinear incommensurate spin-density wave with
propagation vector () at base
temperature in the superconducting parent compound FeTe. This critical
concentration of interstitial iron corresponds to and leads
crystallographic phase separation at base temperature. The spin-density wave is
short-range ordered with a correlation length of 22(3) \AA, and as the ordering
temperature is approached its propagation vector decreases linearly in the
H-direction and becomes long-range ordered. Upon further populating the
interstitial iron site, the spin-density wave gives way to an incommensurate
helical ordering with propagation vector () at base temperature. For a sample with , we
also find an incommensurate spin-density wave that competes with the
bicollinear commensurate ordering close to the N\'eel point. The shifting of
spectral weight between competing magnetic orderings observed in several
samples is supporting evidence for the phase separation being electronic in
nature, and hence leads to crystallographic phase separation around the
critical interstitial iron concentration of 12%. With results from both powder
and single crystal samples, we construct a magnetic-crystallographic phase
diagram of FeTe for $ 5% < x <17%
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County-Level Hispanic Ethnic Density and Cardiovascular Disease Mortality.
Background Hispanics are the fastest growing ethnic group in the United States, and little is known about how Hispanic ethnic population density impacts cardiovascular disease ( CVD ) mortality. Methods and Results We examined county-level deaths for Hispanics and non-Hispanic whites from 2003 to 2012 using data from the National Center for Health Statistics' Multiple Cause of Death mortality files. Counties with more than 20 Hispanic deaths (n=715) were included in the analyses. CVD deaths were identified using International Classification of Diseases, Tenth Revision (ICD-10), I00 to I78, and population estimates were calculated using linear interpolation from 2000 and 2010 census data. Multivariate linear regression was used to examine the association of Hispanic ethnic density with Hispanic and non-Hispanic white age-adjusted CVD mortality rates. County-level age-adjusted CVD mortality rates were adjusted for county-level demographic, socioeconomic, and healthcare factors. There were a total of 4 769 040 deaths among Hispanics (n=382 416) and non-Hispanic whites (n=4 386 624). Overall, cardiovascular age-adjusted mortality rates were higher among non-Hispanic whites compared with Hispanics (244.8 versus 189.0 per 100 000). Hispanic density ranged from 1% to 96% in each county. Counties in the highest compared with lowest category of Hispanic density had 60% higher Hispanic mortality (215.3 versus 134.2 per 100 000 population). In linear regression models, after adjusting for county-level demographic, socioeconomic, and healthcare factors, increasing Hispanic ethnic density remained strongly associated with mortality for Hispanics but not for non-Hispanic whites. Conclusions CVD mortality is higher in counties with higher Hispanic ethnic density. County-level characteristics do not fully explain the higher CVD mortality among Hispanics in ethnically concentrated counties
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