1,191 research outputs found
Integration of perception and reasoning in fast neural modules
Artificial neural systems promise to integrate symbolic and sub-symbolic processing to achieve real time control of physical systems. Two potential alternatives exist. In one, neural nets can be used to front-end expert systems. The expert systems, in turn, are developed with varying degrees of parallelism, including their implementation in neural nets. In the other, rule-based reasoning and sensor data can be integrated within a single hybrid neural system. The hybrid system reacts as a unit to provide decisions (problem solutions) based on the simultaneous evaluation of data and rules. Discussed here is a model hybrid system based on the fuzzy cognitive map (FCM). The operation of the model is illustrated with the control of a hypothetical satellite that intelligently alters its attitude in space in response to an intersecting micrometeorite shower
A Technique to Derive Improved Proper Motions for Kepler Objects of Interest
We outline an approach yielding proper motions with higher precision than
exists in present catalogs for a sample of stars in the Kepler field. To
increase proper motion precision we combine first moment centroids of Kepler
pixel data from a single Season with existing catalog positions and proper
motions. We use this astrometry to produce improved reduced proper motion
diagrams, analogous to a Hertzsprung-Russell diagram, for stars identified as
Kepler Objects of Interest. The more precise the relative proper motions, the
better the discrimination between stellar luminosity classes. With UCAC4 and
PPMXL epoch 2000 positions (and proper motions from those catalogs as
quasi-bayesian priors) astrometry for a single test Channel (21) and Season (0)
spanning two years yields proper motions with an average per-coordinate proper
motion error of 1.0 millisecond of arc per year, over a factor of three better
than existing catalogs. We apply a mapping between a reduced proper motion
diagram and an HR diagram, both constructed using HST parallaxes and proper
motions, to estimate Kepler Object of Interest K-band absolute magnitudes. The
techniques discussed apply to any future small-field astrometry as well as the
rest of the Kepler field.Comment: Accepted to The Astronomical Journal 15 August 201
Topical decolonization does not eradicate the skin microbiota of community-dwelling or hospitalized adults
Topical antimicrobials are often employed for decolonization and infection prevention and may alter the endogenous microbiota of the skin. The objective of this study was to compare the microbial communities and levels of richness and diversity in community-dwelling subjects and intensive care unit (ICU) patients before and after the use of topical decolonization protocols. We enrolled 15 adults at risk for Staphylococcus aureus infection. Community subjects (n = 8) underwent a 5-day decolonization protocol (twice daily intranasal mupirocin and daily dilute bleach-water baths), and ICU patients (n = 7) received daily chlorhexidine baths. Swab samples were collected from 5 anatomic sites immediately before and again after decolonization. A variety of culture media and incubation environments were used to recover bacteria and fungi; isolates were identified using matrix-assisted laser desorption ionization–time of flight mass spectrometry. Overall, 174 unique organisms were recovered. Unique communities of organisms were recovered from the community-dwelling and hospitalized cohorts. In the community-dwelling cohort, microbial richness and diversity did not differ significantly between collections across time points, although the number of body sites colonized with S. aureus decreased significantly over time (P = 0.004). Within the hospitalized cohort, richness and diversity decreased over time compared to those for the enrollment sampling (from enrollment to final sampling, P = 0.01 for both richness and diversity). Topical antimicrobials reduced the burden of S. aureus while preserving other components of the skin and nasal microbiota
Modeling Multi-Wavelength Stellar Astrometry. I. SIM Lite Observations of Interacting Binaries
Interacting binaries consist of a secondary star which fills or is very close
to filling its Roche lobe, resulting in accretion onto the primary star, which
is often, but not always, a compact object. In many cases, the primary star,
secondary star, and the accretion disk can all be significant sources of
luminosity. SIM Lite will only measure the photocenter of an astrometric
target, and thus determining the true astrometric orbits of such systems will
be difficult. We have modified the Eclipsing Light Curve code (Orosz &
Hauschildt 2000) to allow us to model the flux-weighted reflex motions of
interacting binaries, in a code we call REFLUX. This code gives us sufficient
flexibility to investigate nearly every configuration of interacting binary. We
find that SIM Lite will be able to determine astrometric orbits for all
sufficiently bright interacting binaries where the primary or secondary star
dominates the luminosity. For systems where there are multiple components that
comprise the spectrum in the optical bandpass accessible to SIM Lite, we find
it is possible to obtain absolute masses for both components, although
multi-wavelength photometry will be required to disentangle the multiple
components. In all cases, SIM Lite will at least yield accurate inclinations,
and provide valuable information that will allow us to begin to understand the
complex evolution of mass-transferring binaries. It is critical that SIM Lite
maintains a multi-wavelength capability to allow for the proper deconvolution
of the astrometric orbits in multi-component systems.Comment: 12 pages, 6 figures, 6 tables. Accepted for publication in the
Astrophysical Journa
Ground-State Spaces of Frustration-Free Hamiltonians
We study the ground-state space properties for frustration-free Hamiltonians.
We introduce a concept of `reduced spaces' to characterize local structures of
ground-state spaces. For a many-body system, we characterize mathematical
structures for the set of all the -particle reduced spaces, which
with a binary operation called join forms a semilattice that can be interpreted
as an abstract convex structure. The smallest nonzero elements in ,
called atoms, are analogs of extreme points. We study the properties of atoms
in and discuss its relationship with ground states of -local
frustration-free Hamiltonians. For spin-1/2 systems, we show that all the atoms
in are unique ground states of some 2-local frustration-free
Hamiltonians. Moreover, we show that the elements in may not be the
join of atoms, indicating a richer structure for beyond the convex
structure. Our study of deepens the understanding of ground-state
space properties for frustration-free Hamiltonians, from a new angle of reduced
spaces.Comment: 23 pages, no figur
A metaproteomic approach to study human-microbial ecosystems at the mucosal luminal interface
Aberrant interactions between the host and the intestinal bacteria are thought to contribute to the pathogenesis of many digestive diseases. However, studying the complex ecosystem at the human mucosal-luminal interface (MLI) is challenging and requires an integrative systems biology approach. Therefore, we developed a novel method integrating lavage sampling of the human mucosal surface, high-throughput proteomics, and a unique suite of bioinformatic and statistical analyses. Shotgun proteomic analysis of secreted proteins recovered from the MLI confirmed the presence of both human and bacterial components. To profile the MLI metaproteome, we collected 205 mucosal lavage samples from 38 healthy subjects, and subjected them to high-throughput proteomics. The spectral data were subjected to a rigorous data processing pipeline to optimize suitability for quantitation and analysis, and then were evaluated using a set of biostatistical tools. Compared to the mucosal transcriptome, the MLI metaproteome was enriched for extracellular proteins involved in response to stimulus and immune system processes. Analysis of the metaproteome revealed significant individual-related as well as anatomic region-related (biogeographic) features. Quantitative shotgun proteomics established the identity and confirmed the biogeographic association of 49 proteins (including 3 functional protein networks) demarcating the proximal and distal colon. This robust and integrated proteomic approach is thus effective for identifying functional features of the human mucosal ecosystem, and a fresh understanding of the basic biology and disease processes at the MLI. © 2011 Li et al
Joint system quantum descriptions arising from local quantumness
Bipartite correlations generated by non-signalling physical systems that
admit a finite-dimensional local quantum description cannot exceed the quantum
limits, i.e., they can always be interpreted as distant measurements of a
bipartite quantum state. Here we consider the effect of dropping the assumption
of finite dimensionality. Remarkably, we find that the same result holds
provided that we relax the tensor structure of space-like separated
measurements to mere commutativity. We argue why an extension of this result to
tensor representations seems unlikely
A MASSIF Effort To Determine The Mass-Luminosity Relation for Stars of Various Ages, Metallicities, and Evolution States
The MASSIF (Masses and Stellar Systems with Interferometry) Team will use SIM to investigate the mass content of the Galaxy - from huge stars to barely glimmering brown dwarfs, and from hot white dwarfs to exotic black holes. We will target various samples of the Galactic population to determine and relate the fundamental characteristics of mass, luminosity, age, composition, and multiplicity - attributes that together yield an extensive understanding of the stars. Our samples will include distant clusters that span a factor of 5000 in age, and commonplace stars and substellar objects that lurk near the Sun. The principal goals of the MASSIF Key Project are to (1) define the mass-luminosity relation for main sequence stars in five fundamental clusters so that effects of age and metallicity can be mapped (Trapezium, TW Hydrae, Pleiades, Hyades, and M67), and (2) determine accurate masses for representative examples of nearly every type of star, stellar descendant or brown dwarf in the Galaxy
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