763 research outputs found

    Sub-bases of pleasant h-bases

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    On Shellsort and the Frobenius problem

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    Local order measurement in SnGe alloys and monolayer Sn films on Si with reflection electron energy loss spectrometry

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    Measurements of local order are demonstrated in Sn-containing alloys and epitaxial monolayer thickness films by analysis of extended-edge energy loss fine structure (EXELFS) data obtained by reflection electron energy loss spectrometry (REELS). These measurements of short-range order provide a complement to the chemical information obtained with REELS and long-range order obtained using reflection high energy electron diffraction. The results suggest that EXELFS measurements are practical for samples mounted on the growth manipulator in a molecular beam epitaxy chamber. Advantages and limitations of reflection EXELFS are discussed

    In situ reflection electron energy loss spectroscopy measurements of low temperature surface cleaning for Si molecular beam epitaxy

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    In situ analysis of hydrocarbon desorption from hydrogen terminated Si(100) surfaces was performed in a silicon molecular beam epitaxy system, using reflection electron energy loss spectroscopy, in conjunction with conventional reflection high energy electron diffraction analysis. Measurements of C K edge core loss intensities demonstrate that this method is sufficiently sensitive to enable in situ analysis of hydrocarbon desorption at fractional monolayer coverages during low-temperature isothermal anneals. Hydrocarbon desorption was found to begin at 115 °C, and at 200 °C complete desorption occurred within 10 min. Hydrocarbon coverage was not measurably affected by operation of ionization gauge filaments during low temperature anneals, but was increased by transient outgassing of the sample holder, and its environs

    Toward Formalizing Teleportation of Pedagogical Artificial Agents

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    Our paradigm for the use of artificial agents to teach requires among other things that they persist through time in their interaction with human students, in such a way that they “teleport” or “migrate” from an embodiment at one time t to a different embodiment at later time t\u27. In this short paper, we report on initial steps toward the formalization of such teleportation, in order to enable an overseeing AI system to establish, mechanically, and verifiably, that the human students in question will likely believe that the very same artificial agent has persisted across such times despite the different embodiments. The system achieves this by demonstrating to the students that different embodiments share one or more privileged beliefs that only one single agent can possess

    The Frobenius number in the set of numerical semigroups with fixed multiplicity and genus

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    Electronic version of an article published as International Journal of Number Theory, 2017, Vol. 13, No. 04 : pp. 1003-1011 https://doi.org/10.1142/S1793042117500531 © copyright World Scientific Publishing Company http://www.worldscientific.com/We compute all possible numbers that are the Frobenius number of a numerical semigroup when multiplicity and genus are fixed. Moreover, we construct explicitly numerical semigroups in each case.Both authors are supported by the project MTM2014-55367-P, which is funded by Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional FEDER, and by the Junta de Andalucía Grant Number FQM-343. The second author is also partially supported by Junta de Andalucía/Feder Grant Number FQM-5849

    Validation of the cardiovascular risk model NORRISK 2 in South Asians and people with diabetes

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    To evaluate the predictive ability of the previously published NORRISK 2 cardiovascular risk model in Norwegian-born and immigrants born in South Asia living in Norway, and to add information about diabetes and ethnicity in an updated model for South Asians and diabetics (NORRISK 2-SADia). Design. We included participants (30–74 years) born in Norway (n = 13,885) or South Asia (n = 1942) from health surveys conducted in Oslo 2000–2003. Cardiovascular disease (CVD) risk factor information including self-reported diabetes was linked with information on subsequent acute myocardial infarction (AMI) and acute cerebral stroke in hospital and mortality registry data throughout 2014 from the nationwide CVDNOR project. We developed an updated model using Cox regression with diabetes and South Asian ethnicity as additional predictors. We assessed model performance by Harrell’s C and calibration plots. Results. The NORRISK 2 model underestimated the risk in South Asians in all quintiles of predicted risk. The mean predicted 13-year risk by the NORRISK 2 model was 3.9% (95% CI 3.7–4.2) versus observed 7.3% (95% CI 5.9–9.1) in South Asian men and 1.1% (95% CI 1.0–1.2) versus 2.7% (95% CI 1.7–4.2) observed risk in South Asian women. The mean predictions from the NORRISK 2-SADia model were 7.2% (95% CI 6.7–7.6) in South Asian men and 2.7% (95% CI 2.4–3.0) in South Asian women. Conclusions. The NORRISK 2-SADia model improved predictions of CVD substantially in South Asians, whose risks were underestimated by the NORRISK 2 model. The NORRISK 2-SADia model may facilitate more intense preventive measures in this high-risk population.publishedVersio

    Validation of the cardiovascular risk model NORRISK 2 in South Asians and people with diabetes

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    Objectives To evaluate the predictive ability of the previously published NORRISK 2 cardiovascular risk model in Norwegian-born and immigrants born in South Asia living in Norway, and to add information about diabetes and ethnicity in an updated model for South Asians and diabetics (NORRISK 2-SADia). Design. We included participants (30–74 years) born in Norway (n = 13,885) or South Asia (n = 1942) from health surveys conducted in Oslo 2000–2003. Cardiovascular disease (CVD) risk factor information including self-reported diabetes was linked with information on subsequent acute myocardial infarction (AMI) and acute cerebral stroke in hospital and mortality registry data throughout 2014 from the nationwide CVDNOR project. We developed an updated model using Cox regression with diabetes and South Asian ethnicity as additional predictors. We assessed model performance by Harrell’s C and calibration plots. Results. The NORRISK 2 model underestimated the risk in South Asians in all quintiles of predicted risk. The mean predicted 13-year risk by the NORRISK 2 model was 3.9% (95% CI 3.7–4.2) versus observed 7.3% (95% CI 5.9–9.1) in South Asian men and 1.1% (95% CI 1.0–1.2) versus 2.7% (95% CI 1.7–4.2) observed risk in South Asian women. The mean predictions from the NORRISK 2-SADia model were 7.2% (95% CI 6.7–7.6) in South Asian men and 2.7% (95% CI 2.4–3.0) in South Asian women. Conclusions. The NORRISK 2-SADia model improved predictions of CVD substantially in South Asians, whose risks were underestimated by the NORRISK 2 model. The NORRISK 2-SADia model may facilitate more intense preventive measures in this high-risk population.publishedVersio

    CATS Near Real Time Data Products: Applications for Assimilation Into the NASA GEOS-5 AGCM

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    From February 2015 through October 2017, the NASA Cloud-Aerosol Transport System (CATS) backscatter lidar operated on the International Space Station (ISS) as a technology demonstration for future Earth Science Missions, providing vertical measurements of cloud and aerosols properties. Owing to its location on the ISS, a cornerstone technology demonstration of CATS was the capability to acquire, process, and disseminate near-real time (NRT) data within 6 hours of observation time. CATS NRT data has several applications, including providing notification of hazardous events for air traffic control and air quality advisories, field campaign flight planning, as well as for constraining cloud and aerosol distributions in via data assimilation in aerosol transport models. Recent developments in aerosol data assimilation techniques have permitted the assimilation of aerosol optical thickness (AOT), a 2-dimensional column integrated quantity that is reflective of the simulated aerosol loading in aerosol transport models. While this capability has greatly improved simulated AOT forecasts, the vertical position, a key control on aerosol transport, is often not impacted when 2-D AOT is assimilated. Here, we present preliminary efforts to assimilate CATS aerosol observations into the NASA Goddard Earth Observing System version 5 (GEOS-5) atmospheric general circulation model and assimilation system using a 1-D Variational (1-D VAR) ensemble approach, demonstrating the utility of CATS for future Earth Science Missions
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