349 research outputs found

    Breast Cancer Mass Detection using Difference of Gaussians and Pulse Coupled Neural Networks

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    CAD, serving as a second reader, has been shown to improve the success of radiologists at detecting breast cancer. This thesis will develop a new algorithm to identify masses in mammograms. The system developed for this thesis will be capable of assisting a radiologist in making decisions

    On the evaluation of photogrammetric methods for dense 3D surface reconstruction in a metrological context.

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    This paper discusses a methodology to evaluate the accuracy of recently developed image-based 3D modelling techniques. So far, the emergence of these novel methods has not been supported by the definition of an internationally recognized standard which is fundamental for user confidence and market growth. In order to provide an element of reflection and solution to the different communities involved in 3D imaging, a promising approach is presented in this paper for the assessment of both metric quality and limitations of an open-source suite of tools (Apero/MicMac), developed for the extraction of dense 3D point clouds from a set of un- ordered 2D images. The proposed procedural workflow is performed within a metrological context, through inter-comparisons with \u2018reference\u2019 data acquired with two hemispherical laser scanners, one total station, and one laser tracker. The methodology is applied to two case studies, designed in order to analyse the software performances in dealing with both outdoor and environmentally controlled conditions, i.e. the main entrance of Cath\ue9drale de la Major (Marseille, France) and a custom-made scene located at National Research Council of Canada 3D imaging Metrology Laboratory (Ottawa). Comparative data and accuracy evidence produced for both tests allow the study of some key factors affecting 3D model accuracy

    Long-Lived Electron Capture Dissociation Product Ions Experience Radical Migration via Hydrogen Abstraction

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    To explore the mechanism of electron capture dissociation (ECD) of linear peptides, a set of 16-mer peptides were synthesized with deuterium labeled on the α-carbon position of four glycines. The ECD spectra of these peptides showed that such peptides exhibit a preference for the radical to migrate to the α-carbon position on glycine via hydrogen (or deuterium) abstraction before the final cleavage and generation of the detected product ions. The data show c-type fragment ions, ions corresponding to the radical cation of the c-type fragments, c·, and they also show c·-1 peaks in the deuterated peptides only. The presence of the c·-1 peaks is best explained by radical-mediated scrambling of the deuterium atoms in the long-lived, metastable, radical intermediate complex formed by initial electron capture, followed by dissociation of the complex. These data suggest the presence of at least two mechanisms, one slow, one fast. The abundance of H· and −CO losses from the precursor ion changed upon deuterium labeling indicating the presence of a kinetic isotope effect, which suggests that the values reported here represent an underestimation of radical migration and H/D scrambling in the observed fragments

    Genome characteristics of facultatively symbiotic Frankia sp. strains reflect host range and host plant biogeography

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    Soil bacteria that also form mutualistic symbioses in plants encounter two major levels of selection. One occurs during adaptation to and survival in soil, and the other occurs in concert with host plant speciation and adaptation. Actinobacteria from the genus Frankia are facultative symbionts that form N2-fixing root nodules on diverse and globally distributed angiosperms in the “actinorhizal” symbioses. Three closely related clades of Frankia sp. strains are recognized; members of each clade infect a subset of plants from among eight angiosperm families. We sequenced the genomes from three strains; their sizes varied from 5.43 Mbp for a narrow host range strain (Frankia sp. strain HFPCcI3) to 7.50 Mbp for a medium host range strain (Frankia alni strain ACN14a) to 9.04 Mbp for a broad host range strain (Frankia sp. strain EAN1pec.) This size divergence is the largest yet reported for such closely related soil bacteria (97.8%–98.9% identity of 16S rRNA genes). The extent of gene deletion, duplication, and acquisition is in concert with the biogeographic history of the symbioses and host plant speciation. Host plant isolation favored genome contraction, whereas host plant diversification favored genome expansion. The results support the idea that major genome expansions as well as reductions can occur in facultative symbiotic soil bacteria as they respond to new environments in the context of their symbioses

    Dexterity Test Data Contribute To Reduction in Leaded Glovebox Glove Use -9055

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    ABSTRACT Programmatic operations at the Los Alamos National Laboratory Plutonium Facility (TA-55) involve working with various amounts of plutonium and other highly toxic, alpha-emitting materials. The spread of radiological contamination on surfaces, airborne contamination, and excursions of contaminants into the operator's breathing zone are prevented through the use of a variety of gloveboxes. Using an integrated approach, controls have been developed and implemented through an efficient Glovebox Glove Integrity Program. A key element of this program is to consider measures that lower the overall risk of glovebox operations. Line management who own glovebox processes through this program make decisions on which type of glovebox gloves (hereafter referred to as gloves), the weakest component of this safety-significant system, would perform best in these aggressive environments. As Low as Reasonably Achievable considerations must be balanced with glove durability and worker dexterity, both of which affect the final overall risk of the operation. In the past, lead-loaded (leaded) gloves made from Hypalon Âź were the primary glove for programmatic operations at TA-55. Replacing leaded gloves with unleaded gloves for certain operations would lower the overall risk as well as reduce the amount of mixed transuranic waste. This effort contributes to the Los Alamos National Laboratory Continuous Improvement Program by improving the efficiency, cost-effectiveness, and formality of glovebox operations. In this report, the pros and cons of wearing leaded gloves, the effect of leaded gloves versus unleaded gloves on task performance using standard dexterity tests, the justification for switching from leaded to unleaded gloves, and the pollution prevention benefits of this dramatic change in the glovebox system are presented
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