392 research outputs found

    The new tungsten-filament lamp standards of total irradiance

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    Instrumentation and methods used in establishing tungsten-filament lamp standards of total irradianc

    Temperature of a gray body most closely fit- ting the solar extraterrestrial spectrum

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    Temperature measurements of black body most closely fitting solar extraterrestrial spectru

    How Millennials are Engaging and Building Relationships with Organizations on Facebook

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    More than half of Facebook’s 900 million active users in the U.S. consist of the Millennial generation (ages 13 to 29). With more organizations taking advantage of the site’s reach, determining how organizations are interacting with Millennials on Facebook is important.  This study used qualitative focus groups and a quantitative survey to examine how Millennials preferred to interact and engage with organizations on Facebook. Results found participants were not opposed to interacting with organizations on Facebook, but were very specific in terms of how, with who, and why they wanted to engage. While Millennials did want updates and other information depending on the type of organization or group, they also wanted discounts or other benefits. Millennials identified reasons why they would actively terminate the relationship with an organization

    Methods and systems for advanced spaceport information management

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    Advanced spaceport information management methods and systems are disclosed. In one embodiment, a method includes coupling a test system to the payload and transmitting one or more test signals that emulate an anticipated condition from the test system to the payload. One or more responsive signals are received from the payload into the test system and are analyzed to determine whether one or more of the responsive signals comprises an anomalous signal. At least one of the steps of transmitting, receiving, analyzing and determining includes transmitting at least one of the test signals and the responsive signals via a communications link from a payload processing facility to a remotely located facility. In one particular embodiment, the communications link is an Internet link from a payload processing facility to a remotely located facility (e.g. a launch facility, university, etc.)

    Robust plasmon waveguides in strongly-interacting nanowire arrays

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    Arrays of parallel metallic nanowires are shown to provide a tunable, robust, and versatile platform for plasmon interconnects, including high-curvature turns with minimum signal loss. The proposed guiding mechanism relies on gap plasmons existing in the region between adjacent nanowires of dimers and multi-wire arrays. We focus on square and circular silver nanowires in silica, for which excellent agreement between both boundary element method and multiple multipolar expansion calculations is obtained. Our work provides the tools for designing plasmon-based interconnects and achieving high degree of integration with minimum cross talk between adjacent plasmon guides.Comment: 4 pages, 5 figure

    The subpulse modulation properties of pulsars at 92 cm and the frequency dependence of subpulse modulation

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    A large sample of pulsars has been observed to study their subpulse modulation at an observing wavelength (when achievable) of both 21 and 92 cm using the Westerbork Synthesis Radio Telescope. In this paper we present the 92-cm data and a comparison is made with the already published 21-cm results. We analysed 191 pulsars at 92 cm using fluctuation spectra. The sample of pulsars is as unbiased as possible towards any particular pulsar characteristics. For 15 pulsars drifting subpulses are discovered for the first time and 26 of the new drifters found in the 21-cm data are confirmed. We discovered nulling for 8 sources and 8 pulsars are found to intermittently emit single pulses that have pulse energies similar to giant pulses. It is estimated that at least half of the total population of pulsars have drifting subpulses when observations with a high enough signal-to-noise ratio would be available. It could well be that the drifting subpulse mechanism is an intrinsic property of the emission mechanism itself, although for some pulsars it is difficult or impossible to detect. Drifting subpulses are in general found at both frequencies, although the chance of detecting drifting subpulses is possibly slightly higher at 92 cm. It appears that the youngest pulsars have the most disordered subpulses and the subpulses become more and more organized into drifting subpulses as the pulsar ages. The correlations with the modulation indices are argued to be consistent with the picture in which the radio emission can be divided in a drifting subpulse signal plus a quasi-steady signal which becomes, on average, stronger at high observing frequencies. The measured values of P3 at the two frequencies are highly correlated, but there is no evidence for a correlation with other pulsar parameters.Comment: 30 pages, 10 figures, accepted for publication in A&A, astro-ph version is missing 191 figures due to file size restrictions. Please download the appendix from http://www.astron.nl/~stappers/wiki/doku.php?id=resources:publication

    Cohabitation : the Pan-America View

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    In this concluding chapter we reflect on a series of issues of both a methodological and substantive nature encountered in this research project. Firstly, we must realize that the use of individual census records not only opened vast possibilities, but also entails a number of limitations. Secondly, the very large sample sizes allowed for the disaggregation of national trends into far more detailed spatial, ethnic and educational patterns. This, in its turn, allowed us to adopt a "geo-historical" view of the rise of cohabitation for almost the entire American continent, from Alaska to Tierra del Fuego. Furthermore, statistical analyses could be performed at the individual and contextual levels simultaneously. Results show that the effects of social stratification, religion and ethnicity are continuing to be of major importance. This not only holds at the individual level, but at the contextual level as well. Nevertheless, an entirely new wave of change started rolling over the pre-existing patterns from the 1970s onward. These trends are following a firm course, irrespective of the economic ups and downs. The Americas, as opposed to many Asian societies and Africa, are now following in the European footsteps, be it with their own distinct and path-dependent characteristics associated with regionally varying historical antecedents

    The triconnected abstraction of process models

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    Companies use business process models to represent their working procedures in order to deploy services to markets, to analyze them, and to improve upon them. Competitive markets necessitate complex procedures, which lead to large process specifications with sophisticated structures. Real world process models can often incorporate hundreds of modeling constructs. While a large degree of detail complicates the comprehension of the processes, it is essential to many analysis tasks. This paper presents a technique to abstract, i.e., to simplify process models. Given a detailed model, we introduce abstraction rules which generalize process fragments in order to bring the model to a higher abstraction level. The approach is suited for the abstraction of large process specifications in order to aid model comprehension as well as decomposing problems of process model analysis. The work is based on process structure trees that have recently been introduced to the field of business process management
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