4,820 research outputs found

    Development and application of a particle-particle particle-mesh Ewald method for dispersion interactions

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    For inhomogeneous systems with interfaces, the inclusion of long-range dispersion interactions is necessary to achieve consistency between molecular simulation calculations and experimental results. For accurate and efficient incorporation of these contributions, we have implemented a particle-particle particle-mesh (PPPM) Ewald solver for dispersion (r6r^{-6}) interactions into the LAMMPS molecular dynamics package. We demonstrate that the solver's O(NlogN)\mathcal{O}(N\log N) scaling behavior allows its application to large-scale simulations. We carefully determine a set of parameters for the solver that provides accurate results and efficient computation. We perform a series of simulations with Lennard-Jones particles, SPC/E water, and hexane to show that with our choice of parameters the dependence of physical results on the chosen cutoff radius is removed. Physical results and computation time of these simulations are compared to results obtained using either a plain cutoff or a traditional Ewald sum for dispersion.Comment: 31 pages, 9 figure

    Infant Visual Habituation

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    The use of visual habituation in the study of infant cognition and learning is reviewed. This article traces the history of the technique, underlying theory, and procedural variation in its measurement. In addition, we review empirical findings with respect to the cognitive processes that presumably contribute to habituation, studies of developmental course and long-term prediction, as well as recent attempts to address or explain the phenomenon of visual habituation through the use of mathematical or quantitative models. The review ends with an appeal for a return to the study of habituation per se as a valid measure of infant learning, rather than relegating the phenomenon to its use as a technique for familiarizing infants in procedures testing for discrimination or recognition

    Improving Accuracy of Unmanned Aerial System Thermal Infrared Remote Sensing for Use in Energy Balance Models in Agriculture Applications

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    Unmanned aerial system (UAS) remote sensing has rapidly expanded in recent years, leading to the development of several multispectral and thermal infrared sensors suitable for UAS integration. Remotely sensed thermal infrared imagery has been used to detect crop water stress and manage irrigation by leveraging the increased thermal signatures of water stressed plants. Thermal infrared cameras suitable for UAS remote sensing are often uncooled microbolometers. This type of thermal camera is subject to inaccuracies not typically present in cooled thermal cameras. In addition, atmospheric interference also may present inaccuracies in measuring surface temperature. In this study, a UAS with integrated FLIR Duo Pro R (FDPR) thermal camera was used to collect thermal imagery over a maize and soybean field that contained twelve infrared thermometers (IRT) that measured surface temperature. Surface temperature measurements from the UAS FDPR thermal imagery and field IRTs corrected for emissivity and atmospheric interference were compared to determine accuracy of the FDPR thermal imagery. The comparison of the atmospheric interference corrected UAS FDPR and IRT surface temperature measurements yielded a RMSE of 2.24 degree Celsius and a R2 of 0.85. Additional approaches for correcting UAS FDPR thermal imagery explored linear, second order polynomial and artificial neural network models. These models simplified the process of correcting UAS FDPR thermal imagery. All three models performed well, with the linear model yielding a RMSE of 1.27 degree Celsius and a R2 of 0.93. Laboratory experiments also were completed to test the measurement stability of the FDPR thermal camera over time. These experiments found that the thermal camera required a warm-up period to achieve stability in thermal measurements, with increased warm-up duration likely improving accuracy of thermal measurements

    Comparison of Selected Characteristics of Metropolitan Technical Institute Students and On-Campus School of Technology Students

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    Technical Educatio

    The condition of the working class: Representation and praxis

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    Copyright © 2013 Immanuel Ness and Wiley Periodicals, Inc. This is the accepted version of the following article: Wayne, M. and O'Neill, D. (2013), The Condition of the Working Class: Representation and Praxis. WorkingUSA, 16: 487–503, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/wusa.12076/abstract.This essay reflects critically on the political context, production process, ideas, and strategies of our feature-length documentary film The Condition of the Working Class. It explores why we were inspired by Friedrich Engels' 1844 book of the same name and how that book connects with the contemporary neoliberal capitalist project that has dominated the political scene internationally for several decades. We conceptualize our film as a constellation, in the manner of Walter Benjamin, between the 1840s and the contemporary moment. The essay explores the production process of the film, which involved setting up and working in conjunction with a theatrical project. The essay reflects on the theatrical work of John McGrath and its connections with our own work. In the final section of the essay, the authors consider the finished film in more detail, analyzing how the film focused on the process of theatrical production and contextualized that process within wider spatial and temporal frames. The film and the theater project explore the possibility of reconstituting in a microcosm a working class collective subject that has been atomized and demonized by 30 years of neoliberal policy, which in the context of the present economic crisis seeks to drive its project even further

    Metabolic Responses to a Battling Rope Protocol Performed in the Seated or Stance Positions

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    Achieving the recommended amount of physical activity is a greater challenge for individuals who are disabled than those who are not disabled. Battling ropes is an intense exercise that has been shown to promote elevation of heart rate and increased oxygen consumption, and may be a beneficial exercise alternative for individuals with disabilities. PURPOSE: To compare the levels of perceived exertion (RPE), oxygen consumption (VO2) and heart rate (HR) responses elicited by a treadmill (TM) or bicycle (BK) VO2 max test with a standing or sitting battling rope protocol (BRP) (TM vs. standing BRP) (BK vs. seated BRP). To examine the associations between the peak RPE, HR and VO2 responses elicited from the two BRP with their respective VO2 max tests (TM vs. standing BRP) (BK vs. seated BRP). METHODS: Forty healthy subjects, 24 females and 16 males, mean age 24.83 years, performed either a ramped VO2 max TM or BK test (respiratory exchange ratio \u3e 1.0). At least 3 days later, the subjects who performed the ramped TM test did the standing BRP, and the subjects who performed the ramped BK test did the sitting BRP. Each BRP (standing and sitting) consisted of 15 seconds of double arm swings, followed by 45 seconds of rest for 10 rounds. The highest recorded RPE, VO2 and HR values (RPE peak, VO2 peak and HR peak, respectively) were recorded after each round. RESULTS: Metabolic responses were significantly lower for the BRP in both sitting (VO2 peak and HR peak: p \u3c .001) and standing (VO2 peak and HR peak: p \u3c .001) as compared to the HR max and VO2 max values derived from the BK and TM tests. The subjects’ RPE peak elicited from the standing and seated BRP was not significantly different from the RPE peak of the TM or BK, respectively. The BRP produced a VO2 peak that was 71.87% (sitting) and 68.37% (standing) of the subjects\u27 VO2 max assessed via the BK and TM protocol, respectively. Moderate correlations were found between the VO2 during the seated (r = .61; p =.003) and standing (r =.43; p =.03) BRP and the BK and TM VO2 max tests, respectively. The HR peak obtained from the BRP done in sitting (r = .52; p = .009) and standing (r = .67; p = .001) had a moderate correlation with the HR max derived from the BK and TM tests. A moderate correlation was found between the RPE peak elicited from the seated BRP and the BK (r = .55; p = .008). A weak correlation was found between the RPE peak from the standing BRP and the TM (r = .18; p = .22). CONCLUSION: Both the seated and standing BRPs demonstrated the capacity to produce acute metabolic responses that may enhance aerobic capacity. Battling ropes may be a low cost, accessible option to improve cardiovascular endurance for individuals who cannot stand or move their lower extremities in a rhythmic manner to conduct aerobic exercise

    Temporal Trends and Origins of Lake Erie Cadmium Contamination in Relation to Sediment Substrate Type Using Multivariate Kriging Analyses

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    Using the kriging spatial interpolation method, Cd sediment contamination in Lake Erie from 1971 (263 samples) and 1997/1998 (55 samples) were mapped as continuous data surfaces. Although the most recent data set is two decades old, the roughly 25 year period between the two comprehensive lake-wide surveys represents a period of intense binational management action to reduce sources of contamination. To improve interpolation accuracy between two different sampling densities, auxiliary variables including lake-wide sediment substrate types were integrated into spatial analysis of Cd contamination patterns. The potential for adverse biological impacts posed by Cd sediment contamination to humans and aquatic life was measured by the threshold identified contamination along the Long Point Erie Sill and the south-western Ontario shoreline (composed predominately of glacial till) to be in the range of “practically unpolluted” by anthropogenic sources. The highest degree of anthropogenic pollution was found in regions of fine-grained materials (mud and silt). By combining Cd contamination surfaces with sediment substrate categories for analysis of anthropogenically-derived pollution, regions of the lake at higher risk for long-term sediment contamination can be targeted for continued monitoring

    SeaWiFS calibration and validation plan, volume 3

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    The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) will be the first ocean-color satellite since the Nimbus-7 Coastal Zone Color Scanner (CZCS), which ceased operation in 1986. Unlike the CZCS, which was designed as a proof-of-concept experiment, SeaWiFS will provide routine global coverage every 2 days and is designed to provide estimates of photosynthetic concentrations of sufficient accuracy for use in quantitative studies of the ocean's primary productivity and biogeochemistry. A review of the CZCS mission is included that describes that data set's limitations and provides justification for a comprehensive SeaWiFS calibration and validation program. To accomplish the SeaWiFS scientific objectives, the sensor's calibration must be constantly monitored, and robust atmospheric corrections and bio-optical algorithms must be developed. The plan incorporates a multi-faceted approach to sensor calibration using a combination of vicarious (based on in situ observations) and onboard calibration techniques. Because of budget constraints and the limited availability of ship resources, the development of the operational algorithms (atmospheric and bio-optical) will rely heavily on collaborations with the Earth Observing System (EOS), the Moderate Resolution Imaging Spectrometer (MODIS) oceans team, and projects sponsored by other agencies, e.g., the U.S. Navy and the National Science Foundation (NSF). Other elements of the plan include the routine quality control of input ancillary data (e.g., surface wind, surface pressure, ozone concentration, etc.) used in the processing and verification of the level-0 (raw) data to level-1 (calibrated radiances), level-2 (derived products), and level-3 (gridded and averaged derived data) products
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