271 research outputs found
Generative Street Addresses from Satellite Imagery
We describe our automatic generative algorithm to create street addresses from satellite images by learning and labeling roads, regions, and address cells. Currently, 75% of the world’s roads lack adequate street addressing systems. Recent geocoding initiatives tend to convert pure latitude and longitude information into a memorable form for unknown areas. However, settlements are identified by streets, and such addressing schemes are not coherent with the road topology. Instead, we propose a generative address design that maps the globe in accordance with streets. Our algorithm starts with extracting roads from satellite imagery by utilizing deep learning. Then, it uniquely labels the regions, roads, and structures using some graph- and proximity-based algorithms. We also extend our addressing scheme to (i) cover inaccessible areas following similar design principles; (ii) be inclusive and flexible for changes on the ground; and (iii) lead as a pioneer for a unified street-based global geodatabase. We present our results on an example of a developed city and multiple undeveloped cities. We also compare productivity on the basis of current ad hoc and new complete addresses. We conclude by contrasting our generative addresses to current industrial and open solutions. Keywords: road extraction; remote sensing; satellite imagery; machine learning; supervised learning; generative schemes; automatic geocodin
DeepGlobe 2018: A Challenge to Parse the Earth through Satellite Images
We present the DeepGlobe 2018 Satellite Image Understanding Challenge, which
includes three public competitions for segmentation, detection, and
classification tasks on satellite images. Similar to other challenges in
computer vision domain such as DAVIS and COCO, DeepGlobe proposes three
datasets and corresponding evaluation methodologies, coherently bundled in
three competitions with a dedicated workshop co-located with CVPR 2018.
We observed that satellite imagery is a rich and structured source of
information, yet it is less investigated than everyday images by computer
vision researchers. However, bridging modern computer vision with remote
sensing data analysis could have critical impact to the way we understand our
environment and lead to major breakthroughs in global urban planning or climate
change research. Keeping such bridging objective in mind, DeepGlobe aims to
bring together researchers from different domains to raise awareness of remote
sensing in the computer vision community and vice-versa. We aim to improve and
evaluate state-of-the-art satellite image understanding approaches, which can
hopefully serve as reference benchmarks for future research in the same topic.
In this paper, we analyze characteristics of each dataset, define the
evaluation criteria of the competitions, and provide baselines for each task.Comment: Dataset description for DeepGlobe 2018 Challenge at CVPR 201
Experimental determination of the evolution of the Bjorken integral at low Q^2
We extract the Bjorken integral Gamma^{p-n}_1 in the range 0.17 < Q^2 < 1.10
GeV^2 from inclusive scattering of polarized electrons by polarized protons,
deuterons and 3He, for the region in which the integral is dominated by nucleon
resonances. These data bridge the domains of the hadronic and partonic
descriptions of the nucleon. In combination with earlier measurements at higher
Q^2, we extract the non-singlet twist-4 matrix element f_2.Comment: Quoted world data updated. Minor change in some results, Minor
rephrasin
Multisurface plasticity for Cosserat materials: plate element implementation and validation
International audienceThe macroscopic behaviour of materials is affected by their inner micro-structure. Elementary considerations based on the arrangement, and the physical and mechanical features of the micro-structure may lead to the formulation of elastoplastic constitutive laws, involving hardening/softening mechanisms and non-associative properties. In order to model the non-linear behaviour of micro-structured materials, the classical theory of time-independent multisurface plasticity is herein extended to Cosserat continua. The account for plastic relative strains and curvatures is made by means of a robust quadratic-convergent projection algorithm, specifically formulated for non-associative and hardening/softening plasticity. Some important limitations of the classical implementation of the algorithm for multisurface plasticity prevent its application for any plastic surfaces and loading conditions. These limitations are addressed in this paper, and a robust solution strategy based on the Singular Value Decomposition technique is proposed. The projection algorithm is then implemented into a finite element formulation for Cosserat continua. A specific finite element is considered, developed for micropolar plates. The element is validated through illustrative examples and applications, showing able performance
On the magnetic fields generated by experimental dynamos
We review the results obtained by three successful fluid dynamo experiments
and discuss what has been learnt from them about the effect of turbulence on
the dynamo threshold and saturation. We then discuss several questions that are
still open and propose experiments that could be performed to answer some of
them.Comment: 40 pages, 13 figure
Recommended from our members
The use of phylogeny to interpret cross-cultural patterns in plant use and guide medicinal plant discovery: an example from Pterocarpus (Leguminosae)
The study of traditional knowledge of medicinal plants has led to discoveries that have helped combat diseases and improve healthcare. However, the development of quantitative measures that can assist our quest for new medicinal plants has not greatly advanced in recent years. Phylogenetic tools have entered many scientific fields in the last two decades to provide explanatory power, but have been overlooked in ethnomedicinal studies. Several studies show that medicinal properties are not randomly distributed in plant phylogenies, suggesting that phylogeny shapes ethnobotanical use. Nevertheless, empirical studies that explicitly combine ethnobotanical and phylogenetic information are scarce.In this study, we borrowed tools from community ecology phylogenetics to quantify significance of phylogenetic signal in medicinal properties in plants and identify nodes on phylogenies with high bioscreening potential. To do this, we produced an ethnomedicinal review from extensive literature research and a multi-locus phylogenetic hypothesis for the pantropical genus Pterocarpus (Leguminosae: Papilionoideae). We demonstrate that species used to treat a certain conditions, such as malaria, are significantly phylogenetically clumped and we highlight nodes in the phylogeny that are significantly overabundant in species used to treat certain conditions. These cross-cultural patterns in ethnomedicinal usage in Pterocarpus are interpreted in the light of phylogenetic relationships.This study provides techniques that enable the application of phylogenies in bioscreening, but also sheds light on the processes that shape cross-cultural ethnomedicinal patterns. This community phylogenetic approach demonstrates that similar ethnobotanical uses can arise in parallel in different areas where related plants are available. With a vast amount of ethnomedicinal and phylogenetic information available, we predict that this field, after further refinement of the techniques, will expand into similar research areas, such as pest management or the search for bioactive plant-based compounds
Tightening the knot in phytochrome by single molecule atomic force microscopy
A growing number of proteins have been shown to adopt knotted folds. Yet the
biological roles and biophysical properties of these knots remain poorly
understood. We have used protein engineering and atomic force microscopy to
explore single-molecule mechanics of the figure-of-eight knot in the
chromophore-binding domain of the red/far red photoreceptor, phytochrome. Under
load, apo phytochrome unfolds at forces of ~47 pN, while phytochrome carrying
its covalently bound tetrapyrrole chromophore unfolds at ~73 pN. These forces
are among the lowest measured in mechanical protein unfolding, hence the
presence of the knot does not automatically indicate a super-stable protein.
Our experiments reveal a stable intermediate along the mechanical unfolding
pathway, reflecting sequential unfolding of two distinct subdomains in
phytochrome, potentially the GAF and PAS domains. For the first time, our
experiments allow direct determination of knot size under load. In the unfolded
chain, the tightened knot is reduced to 17 amino acids, resulting in apparent
shortening of the polypeptide chain by 6.2 nm. Steered molecular dynamics
simulations corroborate this number. Finally, we found that covalent
phytochrome dimers created for these experiments retain characteristic
photoreversibility, unexpectedly arguing against dramatic rearrangement of the
native GAF dimer interface upon photoconversion.Comment: 12 pages plus five figures; has been submitted to Biophysical J.
Replacement on 9/16 is ONLY to correct a typo in the meta data; the uploaded
file is identical to first versio
Anogenital distance as a marker of androgen exposure in humans.
Abnormal foetal testis development has been proposed to underlie common disorders of the male reproductive system such as cryptorchidism, hypospadias, reduced semen quality and testicular germ cell tumour, which are regarded as components of a 'testicular dysgenesis syndrome'. The increasing trends and geographical variation in their incidence have been suggested to result from in utero exposure to environmental chemicals acting as endocrine disruptors. In rodents, the anogenital distance (AGD), measured from the anus to the base of genital tubercle, is a sensitive biomarker of androgen exposure during a critical embryonic window of testis development. In humans, several epidemiological studies have shown alterations in AGD associated with prenatal exposure to several chemicals with potential endocrine disrupting activity. However, the link between AGD and androgen exposure in humans is not well-defined. This review focuses on the current evidence for such a relationship. As in rodents, a clear gender difference is detected during foetal development of the AGD in humans which is maintained thereafter. Reduced AGD in association with clinically relevant outcomes of potential environmental exposures, such as cryptorchidism or hypospadias, is in keeping with AGD as a marker of foetal testicular function. Furthermore, AGD may reflect variations in prenatal androgen exposure in healthy children as shorter AGD at birth is associated with reduced masculine play behaviour in preschool boys. Several studies provide evidence linking shorter AGD with lower fertility, semen quality and testosterone levels in selected groups of adults attending andrology clinics. Overall, the observational data in humans are consistent with experimental studies in animals and support the use of AGD as a biomarker of foetal androgen exposure. Future studies evaluating AGD in relation to reproductive hormones in both infants and adults, and to gene polymorphisms, will help to further delineate the effect of prenatal and postnatal androgen exposures on AGD.The CBGS studies referred to in this review were supported by a European Union Framework V programme, the World Cancer Research Fund International, the Medical Research Council (UK), the Newlife Foundation, the Mothercare Foundation, the Evelyn Trust and the NIHR Cambridge Biomedical Research Centre.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/andr.1215
Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1GeV2 . I. ep→eπ+n
Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive
Ï€
+
electroproduction reaction
γ
∗
p
→
n
Ï€
+
. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic range covered is
1.1
<
W
<
3
GeV and
1
<
Q
2
<
6
GeV
2
. Results were obtained for about 6000 bins in
W
,
Â
Q
2
,
Â
cos
(
θ
∗
)
, and
Ï•
∗
. Except at forward angles, very large target-spin asymmetries are observed over the entire
W
region. Reasonable agreement is found with phenomenological fits to previous data for
W
<
1.6
GeV, but very large differences are seen at higher values of
W
. A generalized parton distributions (GPD)-based model is in poor agreement with the data. When combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of
Q
2
, for resonances with masses as high as 2.4 GeV
Induced polarization of {\Lambda}(1116) in kaon electroproduction
We have measured the induced polarization of the in the
reaction , detecting the scattered and
in the final state along with the proton from the decay .The present study used the CEBAF Large Acceptance Spectrometer (CLAS),
which allowed for a large kinematic acceptance in invariant energy
( GeV) and covered the full range of the kaon production
angle at an average momentum transfer GeV.In this experiment a
5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target.
We have mapped out the and kaon production angle dependencies of the
induced polarization and found striking differences from photoproduction data
over most of the kinematic range studied. However, we also found that the
induced polarization is essentially independent in our kinematic domain,
suggesting that somewhere below the covered here there must be a strong
dependence. Along with previously published photo- and electroproduction
cross sections and polarization observables, these data are needed for the
development of models, such as effective field theories, and as input to
coupled-channel analyses that can provide evidence of previously unobserved
-channel resonances.Comment: 13 figure
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