538 research outputs found

    Study of dopants for radiation-resistant silicon Final report

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    Radiation effects on electrical properties of both aluminum and lithium doped bulk silico

    Damage coefficients in low resistivity silicon

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    Electron and proton damage coefficients are determined for low resistivity silicon based on minority-carrier lifetime measurements on bulk material and diffusion length measurements on solar cells. Irradiations were performed on bulk samples and cells fabricated from four types of boron-doped 0.1 ohm-cm silicon ingots, including the four possible combinations of high and low oxygen content and high and low dislocation density. Measurements were also made on higher resistivity boron-doped bulk samples and solar cells. Major observations and conclusions from the investigation are discussed

    Using simulation to evaluate how multi-agent transportation planners cope with truck breakdowns

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    The Value of Inaccurate Advance Time Window Information in a Pick-up and Delivery Problem

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    We examine different routing strategies to cope with inaccurate time window in- formation in the context of a dynamic pick-up and delivery problem with time windows. Our experiments show that advance information, even if inaccurate, can provide benefits from a planning perspective. We propose a novel stochastic strategy that consistently performs well compared to several benchmark strategies

    Strategies for Handling Temporal Uncertainty in Pickup and Delivery Problems with Time Windows

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    In many real-life routing problems there is more uncertainty with respect to the required timing of the service than with respect to the service locations. We focus on a pickup and delivery problem with time windows in which the pickup and drop-off locations of the service requests are fully known in advance, but the time at which these jobs will require service is only fully revealed during operations. We develop a sample-scenario routing strategy to accommodate a variety of potential time real- izations while designing and updating the routes. Our experiments on a breadth of instances show that advance time related information, if used intelligently, can yield benefits. Furthermore, we show that it is beneficial to tailor the consensus function that is used in the sample-scenario approach to the specifics of the problem setting. By doing so, our strategy performs well on instances with both short time windows and limited advance confirmation

    Technical Analysis: Exploring MACD in the Lebanese Stock Market

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    The stock markets have shown a great growth in the financial world that required traders to deal with many quantitative methods to analyze markets in order to predict commodities’ future prices. This study assesses the effect of technical analysis on the Lebanese stock markets by using a tool known as the Moving Average Convergence/Divergence (MACD) oscillator that explores how MACD can be utilized to optimize profits in the Lebanese stock exchange, during the trading process. The study is performed on closing prices of shares of six Lebanese banks and a real estate company, over a time period extending from the beginning of the year 2004 till the end of the year 2014. Results are meant to indicate whether MACD is able to optimize profits and forecast the Lebanese stock prices. It is concluded that the application of MACD in the decision making process for investing in the Lebanese stock market does not significantly contribute to the maximization of profitability on investments

    Proton irradiation of swept-charge devices for theChandrayaan-1 X-ray Spectrometer (C1XS)

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    This paper presents work carried out in support of swept-charge device (SCD) characterisation for the Chandrayaan-1 X-ray Spectrometer (C1XS) instrument. A brief overview of the C1XS instrument is presented, followed by a description of SCD structure and operation. The SCD test facility and method of device characterisation using two different drive sequencers to assess leakage current and spectroscopy performance (FWHM and noise at Mn-Kα) are then described. The expected end-of-life (EOL) 10 MeV equivalent proton fluence for the SCDs of C1XS was modelled using Monte Carlo simulation software and used in a subsequent proton irradiation study involving eight SCDs. The irradiation study was carried out at the Kernfysisch Versneller Instituut (KVI) in the Netherlands and characterised the impact of 50 % and 100 % of the expected Chandrayaan-1 EOL proton fluence on the SCD operational characteristics. The radiation environment modelling, irradiation methodology and post-irradiation characterisation of the devices are presented in this paper and recommendations about the planned C1XS operational temperature and shielding are given

    Absence of cardiomyocyte differentiation following transplantation of adult cardiac-resident Sca-1+ cells into infarcted mouse hearts

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    Although several lines of evidence suggest that the glycosyl phosphatidylinositol-anchored cell surface protein Sca-1 marks cardiac-resident stem cells, a critical analysis of the literature raises some concerns regarding their cardiomyogenic potential.1 Here, isolated adult cardiac-resident Sca-1+ cells were engrafted into infarcted hearts and monitored for cardiomyogenic differentiation. Donor cells were prepared from ACT-EGFP; MHC-nLAC double-transgenic mice ([C57/Bl6J x DBA/2J]F1 genetic background; all procedures followed were in accordance with Institutional Guidelines). The ACT-EGFP transgene targets ubiquitous expression of an enhanced green fluorescent protein reporter, and the MHC-nLAC transgene targets cardiomyocyte-restricted expression of a nuclear-localized ÎČ-galactosidase reporter. Donor cell survival was monitored via EGFP fluorescence, while cardiomyogenic differentiation was monitored by reacting with the chromogenic ÎČ-galactosidase substrate 5-bromo-4-chloro-3-indolyl-ÎČ-D-galactoside (X-GAL), which gives rise to a blue product.2 Double-transgenic hearts were dispersed with Blendzyme and the resulting cells reacted with an APC-conjugated anti-Sca-1 antibody and a PE-conjugated cocktail of antibodies recognizing hematopoietic lineage markers.3 Sca-1+, EGFP+, lineage- cells were then isolated via fluorescence-activated cell sorting (FACS; characterization of the donor cells is provided in Figure 1A), and 100,000 cells were injected into the infarct border zone of non-transgenic [C57/Bl6J x DBA/2J]F1 mice immediately following permanent coronary artery occlusion

    Ultrafast Atomic Diffusion Inducing a Reversible (2√3×2√3)R30°↔(√3×√3)R30° Transition on Sn/Si(111)∶B

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    Dynamical phase transitions are a challenge to identify experimentally and describe theoretically. Here, we study a new reconstruction of Sn on silicon and observe a reversible transition where the surface unit cell divides its area by a factor of 4 at 250 °C. This phase transition is explained by the 24-fold degeneracy of the ground state and a novel diffusive mechanism, where four Sn atoms arranged in a snakelike cluster wiggle at the surface exploring collectively the different quantum mechanical ground states.This work was supported by the French Agence Nationale de la Recherche (ANR) under Contract SurMott, No. NT-09-618999, and by Spanish Ministerio de Economía y Competitividad, Project No. MAT2014-59966-R
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