5,114 research outputs found

    Impulse-induced localized nonlinear modes in an electrical lattice

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    Intrinsic localized modes, also called discrete breathers, can exist under certain conditions in one-dimensional nonlinear electrical lattices driven by external harmonic excitations. In this work, we have studied experimentally the efectiveness of generic periodic excitations of variable waveform at generating discrete breathers in such lattices. We have found that this generation phenomenon is optimally controlled by the impulse transmitted by the external excitation (time integral over two consecutive zerosComment: 5 pages, 8 figure

    Driven Intrinsic Localized Modes in a Coupled Pendulum Array

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    Intrinsic localized modes (ILMs), also called discrete breathers, are directly generated via modulational instability in an array of coupled pendulums. These ILMs can be stabilized over a range of driver frequencies and amplitudes. They are characterized by a pi-phase difference between their center and wings. At higher driver frequencies, these ILMs are observed to disintegrate via a pulsating instability, and the mechanism of this breather instability is investigated.Comment: 5 pages, 6 figure

    An Evaluation of Tennessee Soybean Growers’ Views on a New Generation Cooperative to Produce Biodiesel

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    Substituting petroleum diesel with biodiesel could decrease air emissions, reduce reliance on foreign oil, and help expand markets for U.S. farmers. Soybean producers can potentially capture this value-added by forward integrating the processing of soybeans into biodiesel via a New Generation Cooperative (NGC). Using probit analysis, this study examines factors influencing soybean producers’ willingness to participate in an NGC to produce biodiesel. Tobit analysis is used to examine the factors influencing the number of shares the soybean producer would be willing to purchase. Survey results indicate that over 70% of the soybean producers in the study group are interested in investing in an NGC to produce biodiesel. Among those producers willing to participate, the average number of shares they would purchase was just under 3,460.biodiesel, New Generation Cooperative, probit analysis, soybean producers, tobit analysis, Marketing, Research Methods/ Statistical Methods,

    Muscle fibrils: Solubilization and gel electrophoresis

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    In a three-year longitudinal intervention study developing an understanding of statisticalliteracy with a cohort of students from Years 4 to 6, teachers delivered lessons fromprovided materials, including scripts and prompts. Besides completing seven majorinvestigations, workbooks, and several in-class assessments, the students undertook foursurveys, from which their overall progress was determined, as well as individual learningprogressions. Findings indicated that despite experiencing the same lessons delivered insimilar ways, students had very different learning progressions. The implications of thesefindings are explored

    CONSUMER PREFERENCES FOR ELECTRICITY FROM BIOENERGY AND OTHER RENEWABLES

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    This study ascertains residential electricity consumers' support and willingness to pay for electricity from renewable sources. Then, willingness to pay for specified renewable energy sources (solar, wind, landfill wastes, bioenergy from fast growing crops, and bioenergy from forest products wastes). Effects of demographics and environmental behaviors are estimated.Institutional and Behavioral Economics,

    Nonlinear localized modes in two-dimensional electrical lattices

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    We report the observation of spontaneous localization of energy in two spatial dimensions in the context of nonlinear electrical lattices. Both stationary and traveling self-localized modes were generated experimentally and theoretically in a family of two-dimensional square, as well as hon- eycomb lattices composed of 6x6 elements. Specifically, we find regions in driver voltage and frequency where stationary discrete breathers, also known as intrinsic localized modes (ILM), exist and are stable due to the interplay of damping and spatially homogeneous driving. By introduc- ing additional capacitors into the unit cell, these lattices can controllably induce traveling discrete breathers. When more than one such ILMs are experimentally generated in the lattice, the interplay of nonlinearity, discreteness and wave interactions generate a complex dynamics wherein the ILMs attempt to maintain a minimum distance between one another. Numerical simulations show good agreement with experimental results, and confirm that these phenomena qualitatively carry over to larger lattice sizes.Comment: 5 pages, 6 figure

    Farmer Willingness to Supply Poultry Litter for Energy Conversion and to Invest in an Energy Conversion Cooperative

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    Conversion of poultry litter to energy can serve as a renewable energy source and provide an alternative to land application in areas where poultry production is intensive. Economies of size may limit a farmer’s ability to economically use on-farm conversion. Capital costs can be spread across several poultry farmers to convert poultry litter to energy in a centralized facility. This research determined influences on the amount of litter poultry producers will to sell to a centralized conversion facility, on their willingness to invest in a conversion cooperative, and on the prices for litter required to divert litter from current uses.poultry litter, supply, renewable energy, Agribusiness, Agricultural Finance, Farm Management, Financial Economics, Resource /Energy Economics and Policy, Q12, Q13,

    Livestock Farmers\u27 Use of Animal or Herd Health Information Sources

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    Dissemination of animal or herd health information is of potential importance not only to management of a farm business, but may also be critical to animal welfare and public health. Understanding the types of sources of animal/herd health information that farmers use and how farm and farmer characteristics may influence their use is of importance. The objectives of the study reported here were to ascertain the use animal/herd health information sources by livestock producers and the effects of farm and farmer demographic characteristics on use of these information sources. Survey results from 1,737 Tennessee livestock producers are used in the analysis

    Gender Differences in Isokinetic Strength after 60 and 90 d Bed Rest

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    Recent reports suggest that changes in muscle strength following disuse may differ between males and females. PURPOSE: To examine potential gender differences in strength changes following 60 and 90 d of experimental bed rest. METHODS: Isokinetic extensor and flexor strength of the knee (60deg and 180deg/s, concentric only), ankle (30deg/s, concentric and eccentric), and trunk (60deg/s, concentric only) were measured following 60 d (males: n=4, 34.5+/-9.6 y; females: n=4, 35.5+/-8.2 y) and 90 d (males: n=10, 31.4+/-4.8 y; females: n=5, 37.6+/-9.9 y) of 6-degree head-down-tilt bed rest (BR; N=23). Subjects were fed a controlled diet (55%/15%/ 30%, CHO/PRO/FAT) that maintained body weight within 3% of the weight recorded on Day 3 of bed rest. After a familiarization session, testing was conducted 6 d before BR and 2 d after BR completion. Peak torque and total work were calculated for the tests performed. To allow us to combine data from both 60- and 90-d subjects, we used a mixed-model statistical analysis in which time and gender were fixed effects and bed rest duration was a random effect. Log-transformations of strength measures were utilized when necessary in order to meet statistical assumptions. RESULTS: Main effects were seen for both time and gender (p<0.05), showing decreased strength in response to bed rest for both males and females, and males stronger than females for most strength measures. Only one interaction effect was observed: females exhibited a greater loss of trunk extensor peak torque at 60 d versus pre-BR, relative to males (p=0.004). CONCLUSION: Sixty and 90 d of BR induced significant losses in isokinetic muscle strength of the locomotor and postural muscles of the knee, ankle, and trunk. Although males were stronger than females for most of the strength measures that we examined, only changes in trunk extensor peak torque were greater for females than males at day 60 of bed res
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