862 research outputs found

    Semi-Supervised Data Summarization: Using Spectral Libraries to Improve Hyperspectral Clustering

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    Hyperspectral imagers produce very large images, with each pixel recorded at hundreds or thousands of different wavelengths. The ability to automatically generate summaries of these data sets enables several important applications, such as quickly browsing through a large image repository or determining the best use of a limited bandwidth link (e.g., determining which images are most critical for full transmission). Clustering algorithms can be used to generate these summaries, but traditional clustering methods make decisions based only on the information contained in the data set. In contrast, we present a new method that additionally leverages existing spectral libraries to identify materials that are likely to be present in the image target area. We find that this approach simultaneously reduces runtime and produces summaries that are more relevant to science goals

    Addressing VAST 2016 mini challenge 2 with POLAR kermode, classifier, excel on a power wall and data timelines

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    We describe our approach to addressing Mini Challenge 2 of the 2016 IEEE VAST Challenge. We describe four tools: POLAR Kermode, Classifier, Excel with conditional formatting on a power wall and Data Timelines

    Origin, diversification, and classification of the Australasian genus dracophyllum (richeeae, ericaceae)

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    The genus Dracophyllum Labill. (Ericaceae) has a fragmented distribution in Australasia, but reaches the greatest level of species richness and morphological diversity in New Zealand. We investigated evolutionary processes that contribute to this disparity in species richness by comparing DNA sequences from members of Dracophyllum, its close relatives Richea Labill. and Sphenotoma R. Br. ex Sweet (together constituting tribe Richeeae Crayn & Quinn), along with more distant relatives in the Ericaceae. We created complementary data sets for the chloroplast-encoded genes matK and rbcL. Parsimony, Bayesian, and maximum likelihood analyses were conducted to assess the robustness of our phylogenetic inferences. The results were largely congruent and, when analyzed in combination, provided greater resolution. In our analyses, tribe Richeeae formed a monophyletic group that diverged during the Eocene (at least 33.3 million years ago [Ma]) with a crown radiation during the Early Miocene (at least 16.5 Ma) that resulted in two disjunct lineages. This date corresponds roughly to the onset of aridification in central Australia. The southern Western Australian genus Sphenotoma formed an isolated evolutionary lineage, while Dracophyllum and Richea together formed a second lineage restricted to eastern Australia, Lord Howe Island, New Caledonia, and New Zealand. The relationships of the Tasmanian endemic, D. milliganii Hook. f., remain an enigma. It was ambiguously placed as sister to Sphenotoma or to the Dracophyllum Richea elude. We recovered two distinct lineages, traditionally recognized as Richea sect. Cystanthe (R. Br.) Benth. and Richea sect. Dracophylloides Benth., which were nested within Dracophyllum. The Lord Howe Island endemic, D. fitzgeraldii F. Muell., emerged as sister to an eastern Australian clade of Dracophyllum. Our evidence suggests that the New Caledonian and New Zealand species of Dracophyllum dispersed from Australia; we document two independent episodes of long-distance dispersal in the Late Miocene to Early Pliocene. Low levels of sequence divergence suggest a rapid and recent species radiation in these two island archipelagos largely within the last three to six million years. This radiation accompanied Pliocene uplift of the New Zealand Southern Alps and episodes of glaciation during the Pleistocene. Because Dracophyllum is paraphyletic and Richea is polyphyletic, the taxonomic circumscription of these genera requires revision

    The Commensal Real-time ASKAP Fast Transients (CRAFT) survey

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    We are developing a purely commensal survey experiment for fast (<5s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.Comment: accepted for publication in PAS

    Cosmology of a Scalar Field Coupled to Matter and an Isotropy-Violating Maxwell Field

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    Motivated by the couplings of the dilaton in four-dimensional effective actions, we investigate the cosmological consequences of a scalar field coupled both to matter and a Maxwell-type vector field. The vector field has a background isotropy-violating component. New anisotropic scaling solutions which can be responsible for the matter and dark energy dominated epochs are identified and explored. For a large parameter region the universe expands almost isotropically. Using that the CMB quadrupole is extremely sensitive to shear, we constrain the ratio of the matter coupling to the vector coupling to be less than 10^(-5). Moreover, we identify a large parameter region, corresponding to a strong vector coupling regime, yielding exciting and viable cosmologies close to the LCDM limit.Comment: Refs. added, some clarifications. Published in JHEP10(2012)06

    Noether Symmetry Approach in "Cosmic Triad" Vector Field Scenario

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    To realize the accelerations in the early and late periods of our universe, we need to specify potentials for the dominant fields. In this paper, by using the Noether symmetry approach, we try to find suitable potentials in the "cosmic triad" vector field scenario. Because the equation of state parameter of dark energy has been constrained in the range of −1.21≤ω≤−0.89-1.21\leq \omega\leq -0.89 by observations, we derive the Noether conditions for the vector field in quintessence, phantom and quintom models, respectively. In the first two cases, constant potential solutions have been obtained. What is more, a fast decaying point-like solution with power-law potential is also found for the vector field in quintessence model. For the quintom case, we find an interesting constraint C~Vp′=−CVq′\tilde{C}V_{p}'=-CV_{q}' on the field potentials, where CC and C~\tilde{C} are constants related to the Noether symmetry.Comment: 15 pages, no figures, accepted by Classical and Quantum Gravity

    Factors that Determine Catastrophic Expenditure for Tuberculosis Care: a Patient Survey in China

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    Background: Tuberculosis (TB) often causes catastrophic economic effects on both the individual suffering the disease and their households. A number of studies have analyzed patient and household expenditure on TB care, but there does not appear to be any that have assessed the incidence, intensity and determinants of catastrophic health expenditure (CHE) relating to TB care in China. That will be the objective of this paper. Methods: The data used for this study were derived from the baseline survey of the China Government – Gates Foundation TB Phase II program. Our analysis included 747 TB cases. Catastrophic health expenditure for TB care was estimated using two approaches, with households defined as experiencing CHE if their annual expenditure on TB care: (a) exceeded 10 % of total household income; and (b) exceeded 40 % of their non-food expenditure (capacity to pay). Chi-square tests were used to identify associated factors and logistic regression analysis to identify the determinants of CHE. Results: The incidence of CHE was 66.8 % using the household income measure and 54.7 % using non-food expenditure (capacity to pay). An inverse association was observed between CHE rates and household income level. Significant determinants of CHE were: age, household size, employment status, health insurance status, patient income as a percentage of total household income, hospitalization and status as a minimum living security household. Factors including gender, marital status and type of TB case had no significant associations with CHE. Conclusions: Catastrophic health expenditure incidence from TB care is high in China. An integrated policy expanding the free treatment package and ensuring universal coverage, especially the height of UHC for TB patients, is needed. Financial and social protection interventions are essential for identified at-risk groups
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