1,722 research outputs found

    Track train dynamics analysis and test program: Methodology development for the derailment safety analysis of six-axle locomotives

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    The operational safety of six axle locomotives is analyzed. A locomotive model with corresponding data on suspension characteristics, a method of track defect characterization, and a method of characterizing operational safety are used. A user oriented software package was developed as part of the methodology and was used to study the effect (on operational safety) of various locomotive parameters and operational conditions such as speed, tractive effort, and track curvature. The operational safety of three different locomotive designs was investigated

    A new perturbative approach to the adiabatic approximation

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    A new and intuitive perturbative approach to time-dependent quantum mechanics problems is presented, which is useful in situations where the evolution of the Hamiltonian is slow. The state of a system which starts in an instantaneous eigenstate of the initial Hamiltonian is written as a power series which has a straightforward diagrammatic representation. Each term of the series corresponds to a sequence of "adiabatic" evolutions, during which the system remains in an instantaneous eigenstate of the Hamiltonian, punctuated by transitions from one state to another. The first term of this series is the standard adiabatic evolution, the next is the well-known first correction to it, and subsequent terms can be written down essentially by inspection. Although the final result is perhaps not terribly surprising, it seems to be not widely known, and the interpretation is new, as far as we know. Application of the method to the adiabatic approximation is given, and some discussion of the validity of this approximation is presented.Comment: 9 pages. Added references, discussion of previous results, expanded upon discussion of main result and application of i

    The ALICE EMCal L1 trigger first year of operation experience

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    The ALICE experiment at the LHC is equipped with an electromagnetic calorimeter (EMCal) designed to enhance its capabilities for jet, photon and electron measurement. In addition, the EMCal enables triggering on jets and photons with a centrality dependent energy threshold. After its commissioning in 2010, the EMCal Level 1 (L1) trigger was officially approved for physics data taking in 2011. After describing the L1 hardware and trigger algorithms, the commissioning and the first year of running experience, both in proton and heavy ion beams, are reviewed. Additionally, the upgrades to the original L1 trigger design are detailed.Comment: Proceedings of TWEPP-12, Oxford. 10 pages, 9 figure

    Inventaire des mauvaises herbes dans les pépinières ornementales du Québec

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    Un inventaire des mauvaises herbes réalisé au cours de l'été 1986 a permis de visiter 53% des superficies en production ornementale au Québec. Les infestations de mauvaises herbes étaient maintenues à de faibles niveaux dans les pépinières visitées grâce aux sarclages manuels et aux hersages mécaniques fréquents. L'inventaire a révélé que les mauvaises herbes vivaces étaient les plus difficiles à réprimer dans les pépinières. Les mauvaises herbes vivaces les plus fréquemment rencontrées étaient la vesce jargeau (Vicia cracca), le chiendent (Agropyron repens), la prèle des champs (Equisetum arvense) et le souchet comestible (Cyperus esculentus). Les mauvaises herbes identifiées dans les pépinières étaient, pour la plupart, des espèces communes à d'autres cultures. Toutefois, la rorippe d'Islande (Rorippa islandica), la rorippe sylvestre (Rorippa sylvestris) et la cardamine de Pennsylvanie (Cardamine pensylvanica), mauvaises herbes moins connues, ont démontré un fort potentiel d'envahissement dans les pépinières ornementales.A weed survey of fields in ornamental production was conducted in Quebec in 1986 during which 53 % of the production sites were visited. Because of the intensity of hand-weeding and mechanical cultivation used in the fields, no major weed infestations were observed. Weeds most difficult to control were mainly perennial species such as tufted vetch (Vicia cracca), quackgrass (Agropyron repens), field horsetail (Equisetum arvense), and yellow nutsedge (Cyperus esculentus). Most of the weeds identified were species common to other crops. However, marsh yellow cress (Rorippa islandica), yellow field cress (Rorippa sylvestris), and bitter cress (Cardaminepensylvanica) were lesser known weed species that showed a great potential of increase in ornamental nursery production

    Level-1 jet trigger hardware for the ALICE electromagnetic calorimeter at LHC

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    The ALICE experiment at the LHC is equipped with an electromagnetic calorimeter (EMCal) designed to enhance its capabilities for jet measurement. In addition, the EMCal enables triggering on high energy jets. Based on the previous development made for the Photon Spectrometer (PHOS) level-0 trigger, a specific electronic upgrade was designed in order to allow fast triggering on high energy jets (level-1). This development was made possible by using the latest generation of FPGAs which can deal with the instantaneous incoming data rate of 26 Gbit/s and process it in less than 4 {\mu}s.Comment: proceeding of TWEPP-10 at Aachen. 6 pages, 4 figure

    A high-accuracy consensus map of yeast protein complexes reveals modular nature of gene essentiality

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    <p>Abstract</p> <p>Background</p> <p>Identifying all protein complexes in an organism is a major goal of systems biology. In the past 18 months, the results of two genome-scale tandem affinity purification-mass spectrometry (TAP-MS) assays in yeast have been published, along with corresponding complex maps. For most complexes, the published data sets were surprisingly uncorrelated. It is therefore useful to consider the raw data from each study and generate an accurate complex map from a high-confidence data set that integrates the results of these and earlier assays.</p> <p>Results</p> <p>Using an unsupervised probabilistic scoring scheme, we assigned a confidence score to each interaction in the matrix-model interpretation of the large-scale yeast mass-spectrometry data sets. The scoring metric proved more accurate than the filtering schemes used in the original data sets. We then took a high-confidence subset of these interactions and derived a set of complexes using MCL. The complexes show high correlation with existing annotations. Hierarchical organization of some protein complexes is evident from inter-complex interactions.</p> <p>Conclusion</p> <p>We demonstrate that our scoring method can generate an integrated high-confidence subset of observed matrix-model interactions, which we subsequently used to derive an accurate map of yeast complexes. Our results indicate that essentiality is a product of the protein complex rather than the individual protein, and that we have achieved near saturation of the yeast high-abundance, rich-media-expressed "complex-ome."</p

    Quantitative gene expression assessment identifies appropriate cell line models for individual cervical cancer pathways

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    <p>Abstract</p> <p>Background</p> <p>Cell lines have been used to study cancer for decades, but truly quantitative assessment of their performance as models is often lacking. We used gene expression profiling to quantitatively assess the gene expression of nine cell line models of cervical cancer.</p> <p>Results</p> <p>We find a wide variation in the extent to which different cell culture models mimic late-stage invasive cervical cancer biopsies. The lowest agreement was from monolayer HeLa cells, a common cervical cancer model; the highest agreement was from primary epithelial cells, C4-I, and C4-II cell lines. In addition, HeLa and SiHa cell lines cultured in an organotypic environment increased their correlation to cervical cancer significantly. We also find wide variation in agreement when we considered how well individual biological pathways model cervical cancer. Cell lines with an anti-correlation to cervical cancer were also identified and should be avoided.</p> <p>Conclusion</p> <p>Using gene expression profiling and quantitative analysis, we have characterized nine cell lines with respect to how well they serve as models of cervical cancer. Applying this method to individual pathways, we identified the appropriateness of particular cell lines for studying specific pathways in cervical cancer. This study will allow researchers to choose a cell line with the highest correlation to cervical cancer at a pathway level. This method is applicable to other cancers and could be used to identify the appropriate cell line and growth condition to employ when studying other cancers.</p
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