1,510 research outputs found
Wave propagation through soils in centrifuge testing.
International audienceWave propagation phenomena in soils can be experimentally simulated using centrifuge scale models. An original excitation device (drop-ball arrangement) is proposed to generate short wave trains. Wave reflections on model boundaries are taken into account and removed by homomorphic filtering. Propagation is investigated through dispersion laws. For drop-ball experiments, spherical wave field analysis assuming linear viscoelasticity leads to a complete analytical description of wave propagation. Damping phenomena are examined and evaluated using this description
Microbial ecology of Thiobacillus ferrooxidans
FINAL TECHNICAL REPORT
TO
U.S. DEPARTMENT OF THE INTERIOR
Geological Survey
Washington. D.C.The contents of this report were developed in part under a grant from
the Department of the Interior, U.S. Geological Survey. Grant number 14-08-0001-61313
3D Hopkinson bar: new experiments for dynamic testing on soils.
International audienceThe direct analysis of the dynamic response of materials is possible using Split Hopkinson pressure bar method. For soils, it has to be adapted since the specimen has generally poor mechanical properties. An original experimental arrangement called "Three-Dimensional Split Hopkinson Pressure Bar" (3D SHPB) is proposed. It allows the measurement of the complete three-dimensional dynamic response of soils. Different types of confinement systems are used. The results on different loading paths are compared with other works on sand and clay. The analysis at grain-size level gives further elements on the comminution process
Increased risk for a second retroviral infection (SIV or STLV type 1) for wild African green monkeys already infected by one retrovirus in Senegal (West Africa)
Complete Fusion Enhancement and Suppression of Weakly Bound Nuclei at Near Barrier Energies
We consider the influence of breakup channels on the complete fusion of
weakly bound systems in terms of dynamic polarization potentials. It is argued
that the enhancement of the cross section at sub-barrier energies may be
consistent with recent experimental observations that nucleon transfer, often
leading to breakup, is dominant compared to direct breakup. The main trends of
the experimental complete fusion cross section for Li + Bi are
analyzed in the framework of the DPP approach.Comment: 12 pages, 2 figure
Asynchronous Training of Word Embeddings for Large Text Corpora
Word embeddings are a powerful approach for analyzing language and have been
widely popular in numerous tasks in information retrieval and text mining.
Training embeddings over huge corpora is computationally expensive because the
input is typically sequentially processed and parameters are synchronously
updated. Distributed architectures for asynchronous training that have been
proposed either focus on scaling vocabulary sizes and dimensionality or suffer
from expensive synchronization latencies.
In this paper, we propose a scalable approach to train word embeddings by
partitioning the input space instead in order to scale to massive text corpora
while not sacrificing the performance of the embeddings. Our training procedure
does not involve any parameter synchronization except a final sub-model merge
phase that typically executes in a few minutes. Our distributed training scales
seamlessly to large corpus sizes and we get comparable and sometimes even up to
45% performance improvement in a variety of NLP benchmarks using models trained
by our distributed procedure which requires of the time taken by the
baseline approach. Finally we also show that we are robust to missing words in
sub-models and are able to effectively reconstruct word representations.Comment: This paper contains 9 pages and has been accepted in the WSDM201
Predicting wet age-related macular degeneration (AMD) using DARC (detecting apoptosing retinal cells) AI (artificial intelligence) technology
Objectives:
To assess a recently described CNN (convolutional neural network) DARC (Detection of Apoptosing Retinal Cells) algorithm in predicting new Subretinal Fluid (SRF) formation in Age-related-Macular-Degeneration (AMD).
Methods:
Anonymized DARC, baseline and serial OCT images (n = 427) from 29 AMD eyes of Phase 2 clinical trial (ISRCTN10751859) were assessed with CNN algorithms, enabling the location of each DARC spot on corresponding OCT slices (n = 20,629). Assessment of DARC in a rabbit model of angiogenesis was performed in parallel.
Results:
A CNN DARC count >5 at baseline was significantly (p = 0.0156) related to development of new SRF throughout 36 months. Prediction rate of eyes using unique DARC spots overlying new SRF had positive predictive values, sensitivities and specificities >70%, with DARC count significantly (p < 0.005) related to the magnitude of SRF accumulation at all time points. DARC identified earliest stages of angiogenesis in-vivo.
Conclusions:
DARC was able to predict new wet-AMD activity. Using only an OCT-CNN definition of new SRF, we demonstrate that DARC can identify early endothelial neovascular activity, as confirmed by rabbit studies. Although larger validation studies are required, this shows the potential of DARC as a biomarker of wet AMD, and potentially saving vision-loss
The Gattini cameras for optical sky brightness measurements at Dome C, Antarctica
The Gattini cameras are two site testing instruments for
the measurement of optical sky brightness, large area cloud cover and auroral detection of the night sky above the high altitude Dome C site in Antarctica. The cameras have been operating since installation in January 2006 and are currently at the end of the first Antarctic winter season. The cameras are transit in nature and are virtually identical both adopting Apogee Alta CCD detectors. By taking frequent images of the night sky we obtain long term cloud cover statistics, measure the sky background intensity as a function of solar and lunar altitude and
phase and directly measure the spatial extent of bright aurora if present and when they occur. The full data set will return in December 2006 however a limited amount of data has been transferred via the Iridium network enabling preliminary data reduction and system evaluation.
An update of the project is presented together with preliminary results from data taken since commencement of the winter season
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