964 research outputs found

    Beryllium fastener technology

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    Program was conducted to develop, produce, and test optimum-configuration, beryllium prestressed and blind fasteners. The program was carried out in four phases - phase 1, feasibility study, phase 2, development, phase 3, evaluation of beryllium alloys, and phase 4, fabrication and testing

    EFL and/vs. ESL? A multi-level regression modeling perspective on bridging the paradigm gap

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    The study of learner language and of indigenized varieties are growing areas of English-language corpus-linguistic research, which are shaped by two current trends: First, the recognition that more rigorous methodological approaches are urgently needed: with few exceptions, existing work is based on over-/under-use frequency counts that fail to unveil complex non-native linguistic patterns; second, the collective effort to bridge an existing "paradigm gap " (Sridhar & Sridhar 1986) between EFL and ESL research. This paper contributes to these developments by offering a multifactorial analysis of seventeen lexical verbs in the dative alternation in speech and writing of German/French learners and Hong Kong/India/Singapore English speakers. We exemplify the advantages of hierarchical mixed-effects modeling, which allows us to control for speaker and verb-specific effects, but also for the hierarchical structure of the corpus data. Second, we address the theoretical question of whether EFL and ESL represent discrete English varieties or a continuum

    Random and exhaustive generation of permutations and cycles

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    In 1986 S. Sattolo introduced a simple algorithm for uniform random generation of cyclic permutations on a fixed number of symbols. This algorithm is very similar to the standard method for generating a random permutation, but is less well known. We consider both methods in a unified way, and discuss their relation with exhaustive generation methods. We analyse several random variables associated with the algorithms and find their grand probability generating functions, which gives easy access to moments and limit laws.Comment: 9 page

    Nota introdutória do editor

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    Field testing T-22™ Planter Box for corn in Iowa

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    Several corn producers used precision farming technologies to evaluate a new product that is reported to enhance nitrogen (N) use by plants. The studies demonstrate that precision farming technologies make it possible for groups of producers to objectively assess the value of new products as soon as they appear on the market

    How Flies Are Flirting on the Fly

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    Background  Flies have some of the most elaborate visual systems in the Insecta, often featuring large, sexually dimorphic eyes with specialized “bright zones” that may have a functional role during mate-seeking behavior. The fast visual system of flies is considered to be an adaptation in support of their advanced flight abilities. Here, we show that the immense processing speed of the flies’ photoreceptors plays a crucial role in mate recognition. Results  Video-recording wing movements of abdomen-mounted common green bottle flies, Lucilia sericata, under direct light at 15,000 frames per second revealed that wing movements produce a single, reflected light flash per wing beat. Such light flashes were not evident when we video-recorded wing movements under diffuse light. Males of L. sericata are strongly attracted to wing flash frequencies of 178 Hz, which are characteristic of free-flying young females (prospective mates), significantly more than to 212, 235, or 266 Hz, characteristic of young males, old females, and old males, respectively. In the absence of phenotypic traits of female flies, and when given a choice between light emitting diodes that emitted either constant light or light pulsed at a frequency of 110, 178, 250, or 290 Hz, males show a strong preference for the 178-Hz pulsed light, which most closely approximates the wing beat frequency of prospective mates. Conclusions  We describe a previously unrecognized visual mate recognition system in L. sericata. The system depends upon the sex- and age-specific frequencies of light flashes reflecting off moving wings, and the ability of male flies to distinguish between the frequency of light flashes produced by rival males and prospective mates. Our findings imply that insect photoreceptors with fast processing speed may not only support agile flight with advanced maneuverability but may also play a supreme role in mate recognition. The low mating propensity of L. sericata males on cloudy days, when light flashes from the wings of flying females are absent, seems to indicate that these flies synchronize sexual communication with environmental conditions that optimize the conspicuousness of their communication signals, as predicted by sensory drive theory

    Interaction of (3-Aminopropyl)triethoxysilane with Pulsed Ar-O 2 Afterglow: Application to Nanoparticles Synthesis

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    International audienceThe interaction of (3-Aminopropyl)triethoxysilane (APTES) with pulsed late Ar-O 2 afterglow is characterized by the synthesis of OH, CO and CO 2 in the gas phase as main by-products. Other minor species like CH, CN and C 2 H are also produced. We suggest that OH radicals are produced in a first step by dehydrogenation of APTES after interaction with oxygen atoms. In a second step, the molecule is oxidized by any O 2 state, to form peroxides that transform into by-products, break thus the precursor CC bonds. If oxidation is limited, i.e. a low duty cycle, fragmentation of the precursor is limited and produced nanoparticles keep the backbone structure of the precursor, but contain amide groups produced from the amine groups initially available in APTES. At high duty cycle, silicon-containing fragments contain some carbon and react together and produce nanoparticles with a non-silica-like structure

    ecocomDP: A flexible data design pattern for ecological community survey data

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    The idea of harmonizing data is not new. Decades of amassing data in databases according to community standards - both locally and globally - have been more successful for some research domains than others. It is particularly difficult to harmonize data across studies where sampling protocols vary greatly and complex environmental conditions need to be understood to apply analytical methods correctly. However, a body of longterm ecological community observations is increasingly becoming publicly available and has been used in important studies. Here, we discuss an approach to preparing harmonized community survey data by an environmental data repository, in collaboration with a national observatory. The workflow framework and repository infrastructure are used to create a decentralized, asynchronous model to reformat data without altering original data through cleaning or aggregation, while retaining metadata about sampling methods and provenance, and enabling programmatic data access. This approach does not create another data ‘silo’ but will allow the repository to contribute subsets of available data to a variety of different analysis-ready data preparation efforts. With certain limitations (e.g., changes to the sampling protocol over time), data updates and downstream processing may be completely automated. In addition to supporting reuse of community observation data by synthesis science, a goal for this harmonization and workflow effort is to contribute these datasets to the Global Biodiversity Information Facility (GBIF) to increase the data’s discovery and use

    Data Model Canvas für die IT-Systemübergreifende Integration von Datenmodellen zur Unterstützung von Datenanalyse-Anwendungen im Produktlebenszyklus

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    Der Data Model Canvas (DMC) unterstützt methodisch und informationstechnisch den Aufbau der für ein durchgängiges und interdisziplinäres Engineering benötigten fachlichen Datengrundlage und deren Abbildung in den betreffenden IT-Systemen. Basierend auf konkreten Analyse-Szenarien erfolgt eine Modellierung der erforderlichen Datenvernetzung, die wiederum die explizit benötigten Datenquellen umfasst. Im Mittelpunkt dieses Ansatzes steht die Entwicklung eines fachlichen Verständnisses über die zur Analyse notwendigen roduktdaten. Unterstützt wird der Ansatz durch ein Softwaretool zur Erstellung der benötigten Datenmodelle
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