1,621 research outputs found

    Modular space station mockup review and evaluation

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    The modular space station mockup is described in detail with emphasis on the interior arrangements of the crew living spaces, control center, and general purpose laboratory facilities. The results of three mockup reviews are also presented

    Criticality in Dynamic Arrest: Correspondence between Glasses and Traffic

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    Dynamic arrest is a general phenomenon across a wide range of dynamic systems, but the universality of dynamic arrest phenomena remains unclear. We relate the emergence of traffic jams in a simple traffic flow model to the dynamic slow down in kinetically constrained models for glasses. In kinetically constrained models, the formation of glass becomes a true (singular) phase transition in the limit T→0T\to 0. Similarly, using the Nagel-Schreckenberg model to simulate traffic flow, we show that the emergence of jammed traffic acquires the signature of a sharp transition in the deterministic limit \pp\to 1, corresponding to overcautious driving. We identify a true dynamical critical point marking the onset of coexistence between free flowing and jammed traffic, and demonstrate its analogy to the kinetically constrained glass models. We find diverging correlations analogous to those at a critical point of thermodynamic phase transitions.Comment: 4 pages, 4 figure

    Using Social Marketing Principles to Understand an Extension Audience’s Landscape Water Conservation Practices

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    A substantial amount of water is applied to Florida landscapes, and encouraging water conservation through irrigation practices has been identified as a priority programming area where there is great opportunity to positively affect the state’s water resources. Florida Extension addresses this priority area through educational programming. Social marketing has been identified as a promising approach to changing behaviors that influence environmental issues, such as water-saving irrigation technologies and practices. This approach recognizes that there are barriers that prevent individuals from engaging in positive behavior changes. This study evaluated an irrigation seminar using a retrospective pretest-posttest design that incorporated elements of a social marketing intercept survey. Thirty-four attendees participated and primarily represented green industry professional and government sectors. Study objectives were to evaluate the workshop and describe the audience using social marketing principles for future program planning based on audience research. The audience rated their descriptive norms, a strong predictor of behavioral change, lower than their injunctive norms, a less robust predictor. The majority planned to adopt at least one water-conservation best management practice as a result of the workshop. We make recommendations for applying social marketing principles to Extension programming

    Modular space station phase B extension preliminary system design. Volume 2: Operations and crew analyses

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    All analyses and tradeoffs conducted to establish the MSS operations and crew activities are discussed. The missions and subsystem integrated analyses that were completed to assure compatibility of program elements and consistency with program objectives are presented

    Shear-induced anisotropic decay of correlations in hard-sphere colloidal glasses

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    Spatial correlations of microscopic fluctuations are investigated via real-space experiments and computer simulations of colloidal glasses under steady shear. It is shown that while the distribution of one-particle fluctuations is always isotropic regardless of the relative importance of shear as compared to thermal fluctuations, their spatial correlations show a marked sensitivity to the competition between shear-induced and thermally activated relaxation. Correlations are isotropic in the thermally dominated regime, but develop strong anisotropy as shear dominates the dynamics of microscopic fluctuations. We discuss the relevance of this observation for a better understanding of flow heterogeneity in sheared amorphous solids.Comment: 6 pages, 4 figure

    Identification of key effects causing weak performance of allergen analysis in processed food matrices

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    The weaker performance of generally used analytical methods for allergen analysis in processed foods can be connected to protein denaturation. To understand the nature of protein denaturation processes, experimental but realistic model matrices (corn starch based mixture, hydrated dough, and heat treated cookies) were developed that contain a defined amount of milk, egg, soy, and wheat proteins individually or in combination. The protein subunit composition was investigated in every processing phase, i.e. after mixing, dough formation, and baking. SDS-PAGE measurements were carried out to monitor the protein distribution of sample food matrices in non-reducing and reducing gels. The results clearly show that the highly decreased protein solubility is caused by denaturation, aggregation, or complex formation, which are the most significant factors in poorer analytical performances. Solubility can only partly be improved with the application of reducing agents or surfactants, and the rate of improvement is depending on the proteins and the matrices

    Yielding and irreversible deformation below the microscale: Surface effects and non-mean-field plastic avalanches

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    Nanoindentation techniques recently developed to measure the mechanical response of crystals under external loading conditions reveal new phenomena upon decreasing sample size below the microscale. At small length scales, material resistance to irreversible deformation depends on sample morphology. Here we study the mechanisms of yield and plastic flow in inherently small crystals under uniaxial compression. Discrete structural rearrangements emerge as series of abrupt discontinuities in stress-strain curves. We obtain the theoretical dependence of the yield stress on system size and geometry and elucidate the statistical properties of plastic deformation at such scales. Our results show that the absence of dislocation storage leads to crucial effects on the statistics of plastic events, ultimately affecting the universal scaling behavior observed at larger scales.Comment: Supporting Videos available at http://dx.plos.org/10.1371/journal.pone.002041

    Assessment of Smallmouth Bass Growth and Mortality in Nebraska Waters

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    Smallmouth bass (Micropterus dolomieu) have been introduced across Nebraska into a variety of waterbodies. However, an estimate of smallmouth bass growth and mortality in Nebraska waters has not been produced. The objectives of this study were to use historic sampling data to describe the growth of smallmouth bass in Nebraska lakes in relation to other regional models, growth among waterbody types (reservoirs, Interstate 80 [I-80] lakes, and rivers), estimates of age at quality, preferred, and memorable lengths, and mortality for Nebraska smallmouth bass populations. Mean length ± SE of Nebraska smallmouth bass at age 7 was 383 ± 21 mm, which is similar to national and regional values. Mean lengths at age of smallmouth bass in I-80 lakes and reservoirs were similar, but lengths were larger in rivers than in I-80 lakes and reservoirs at ages 3–5. Mean total annual mortality measured 0.41 (± 0.06 SE). These growth and mortality rates allow biologists to set appropriate management objectives and assess local sampling results with proper perspectives

    Language and Literacy Practices of Bilingual Education Preservice Teachers at a Hispanic-Serving College of Education

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    This chapter focuses on an exploratory study of the language and literacy practices of undergraduate students within our Hispanic-Serving College of Education (HSCOE). HSCOEs must first understand and approach the language and literacy practices of bilingual education preservice teachers from an asset-based perspective. Language and literacy practices shape people’s identities and how they exist in the world. Language and literacy development also have an essential role in adult success since reading allows people to access, analyze, synthesize, and use knowledge to understand the world and learn new things. Much of the literature related to language and literacy practices at the postsecondary level focuses on academic literacy, especially the particular language of higher education and academia. The intersection of language and academic preparedness and performance for bilingual Latinx students is particularly noteworthy. The bilingual education preservice teachers used multiple linguistic codes and engaged in translanguaging in various aspects of their lives

    Incentivizing High Quality Crowdwork

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    We study the causal effects of financial incentives on the quality of crowdwork. We focus on performance-based payments (PBPs), bonus payments awarded to workers for producing high quality work. We design and run randomized behavioral experiments on the popular crowdsourcing platform Amazon Mechanical Turk with the goal of understanding when, where, and why PBPs help, identifying properties of the payment, payment structure, and the task itself that make them most effective. We provide examples of tasks for which PBPs do improve quality. For such tasks, the effectiveness of PBPs is not too sensitive to the threshold for quality required to receive the bonus, while the magnitude of the bonus must be large enough to make the reward salient. We also present examples of tasks for which PBPs do not improve quality. Our results suggest that for PBPs to improve quality, the task must be effort-responsive: the task must allow workers to produce higher quality work by exerting more effort. We also give a simple method to determine if a task is effort-responsive a priori. Furthermore, our experiments suggest that all payments on Mechanical Turk are, to some degree, implicitly performance-based in that workers believe their work may be rejected if their performance is sufficiently poor. Finally, we propose a new model of worker behavior that extends the standard principal-agent model from economics to include a worker's subjective beliefs about his likelihood of being paid, and show that the predictions of this model are in line with our experimental findings. This model may be useful as a foundation for theoretical studies of incentives in crowdsourcing markets.Comment: This is a preprint of an Article accepted for publication in WWW \c{opyright} 2015 International World Wide Web Conference Committe
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