11,440 research outputs found

    THE POTENTIAL FOR EXPORTING VEGETABLES FROM THE PERSPECTIVE OF U.S. EXPORTERS

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    Crop Production/Industries, International Relations/Trade,

    A simple test for thermomechanical evaluation of ceramic fibers

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    A simple bend stress relaxation (BSR) test was developed to measure the creep related properties of ceramic fibers and whiskers. The test was applied to a variety of commercial and developmental Si based fibers to demonstrate capabilities and to evaluate the relative creep resistance of the fibers at 1200 to 1400 C. The implications of these results and the advantages of the BSR test over typical tensile creep tests are discussed

    Intermittent Synchronization in a Pair of Coupled Chaotic Pendula

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    Numerical simulations have been carried out for a pair of unidirectionally coupled identical pendula under the action of a common external ac torque. Both the master pendulum and the slave pendulum were in chaotic states. The only form of persistent locking appeared to be a computational artifact; otherwise the synchronization of slave to master was found to be intermittent

    First North American record of the Palaearctic rhinophorid Stevenia deceptoria (Loew) (Diptera: Rhinophoridae)

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    The Rhinophoridae (Diptera) have a cosmopolitan distribution and a known fauna of about 150 species (Cerretti & Pape 2007). So far as known, all species are parasitoids of terrestrial woodlice (sow bugs) of the order Isopoda (Oniscoidea) (Pape 2010). Female rhinophorids lay eggs in the vicinity of potential hosts and the planidial first instars parasitize sow bugs as they pass by (Pape 1998). The only rhinophorids native to North America belong to the genera Apomorphyto Cerretti, Lo Giudice & Pape (with one described species from Costa Rica and an undetermined species from Nicaragua) and Bezzimyia Townsend (Pape 2010; Cerretti et al. 2014). Bezzimyia is a mostly Neotropical genus of 17 known species with two species reaching the southern United States (Texas and Arizona) (Pape & Arnaud 2001). Recently, the monophyly of Bezzimyia was called into question but the limits of the genus have yet to be formally revised (Cerretti et al. 2014). Two rhinophorids are well known as introductions from the Palaearctic Region, Melanophora roralis (Linnaeus) and Phyto discrepans Pandellé, with the former widespread in eastern North America, West Indies and South America (Crosskey 1977; Pape 2010) and the latter known only from Newfoundland (Canada) (Wood 1987). A key to separate the two species was given by Wood (1987). The genus Stevenia Robineau-Desvoidy is currently known from 23 species, all native to the Old World and most diverse in the West Palaearctic Region (Cerretti & Pape 2007). One species native to Europe and North Africa, Stevenia deceptoria (Loew), was reported recently as an introduction to Argentina by Mulieri et al. (2010). The authors recorded the species from several locations within Buenos Aires Province and hypothesized that it became established through the introduction of parasitized woodlice originating from the Palaearctic Region. Introduced woodlice are common in the New World (Jass & Klausmeier 2000) and parasitized immigrants or transported puparia most likely account for the presence of all three exotic rhinophorid species in North America. Mulieri et al. (2010) summarized the Palaearctic distribution of S. deceptoria, gave locality records of the species in Argentina, and provided a key to the five genera of Rhinophoridae known from the New World. Here we report another finding of Stevenia deceptoria in the Americas, this time from Ohio in North America. All records are from a single locality, the backyard of author GAD. Specimens were caught in a six metre Malaise trap (BioQuip® Products, Inc.) and killed in the trap head using a small piece of Hot Shot® No-Pest® Strip [active ingredient 2,2-dichlorovinyl dimethyl phosphate 18.6%]. Trap samples were frozen and later sorted, with selected Diptera subsequently pinned and labeled. The first two specimens of S. deceptoria to be detected were removed, pinned, and labeled by JEOH and identified as S. deceptoria by PC (Cerretti & Pape 2007) (one of these specimens is shown in Fig. 1). Additional specimens were later found in earlier and later samples by GAD. Specimens are housed in the Canadian National Collection of Insects, Ottawa, Canada (CNC) and the personal collection of Gregory Dahlem, Cincinnati, USA (GAD)

    Intermittent Synchronization of Resistively Coupled Chaotic Josephson Junctions

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    Numerical simulations have been used to investigate the dynamics of a pair of resistively linked Josephson junctions with ac bias. For suitable choices of parameters, the chaotic states of the two junctions become intermittently synchronized. Intervals of synchronization are interleaved between bursts of desynchronized activity. The distributions of these laminar times and their dependence on the coupling strength are determined. The role of phase winding in the definition of synchronization intervals is considered

    Inverting Chaos: Extracting System Parameters from Experimental Data

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    Given a set of experimental or numerical chaotic data and a set of model differential equations with several parameters, is it possible to determine the numerical values for these parameters using a least-squares approach, and thereby to test the model against the data? We explore this question (a) with simulated data from model equations for the Rossler, Lorenz, and pendulum attractors, and (b) with experimental data produced by a physical chaotic pendulum. For the systems considered in this paper, the least-squares approach provides values of model parameters that agree well with values obtained in other ways, even in the presence of modest amounts of added noise. For experimental data, the “fitted” and experimental attractors are found to have the same correlation dimension and the same positive Lyapunov exponent

    Techniques for Teaching ESL to Refugees

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    This project is an attempt to provide the inexperienced tutor of English to refugees with some commonly used techniques. Most of the techniques presented are not difficult to learn to use effectively. Each technique is presented with its rationale, procedure for use and an example. A discussion of techniques and their uses, objectives, and on teaching and learning precedes the presentation of the techniques
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