3,403 research outputs found

    Unsteady aerodynamics of an oscillating cascade in a compressible flow field

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    Fundamental experiments were performed in the NASA Lewis Transonic Oscillating Cascade Facility to investigate and quantify the unsteady aerodynamics of a cascade of biconvex airfoils executing torsion-mode oscillations at realistic reduced frequencies. Flush-mounted, high-response miniature pressure transducers were used to measure the unsteady airfoil surface pressures. The pressures were measured for three interblade phase angles at two inlet Mach numbers, 0.65 and 0.80, and two incidence angles, 0 and 7 deg. The time-variant pressures were analyzed by means of discrete Fourier transform techniques, and these unique data were then compared with predictions from a linearized unsteady cascade model. The experimental results indicate that the interblade phase angle had a major effect on the chordwise distributions of the airfoil surface unsteady pressure, and that reduced frequency, incidence angle, and Mach number had a somewhat less significant effect

    Enhancement and suppression effects resulting from information structuring in sentences

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    Information structuring through the use of cleft sentences increases the processing efficiency of references to elements within the scope of focus. Furthermore, there is evidence that putting certain types of emphasis on individual words not only enhances their subsequent processing, but also protects these words from becoming suppressed in the wake of subsequent information, suggesting mechanisms of enhancement and suppression. In Experiment 1, we showed that clefted constructions facilitate the integration of subsequent sentences that make reference to elements within the scope of focus, and that they decrease the efficiency with reference to elements outside of the scope of focus. In Experiment 2, using an auditory text-change-detection paradigm, we showed that focus has similar effects on the strength of memory representations. These results add to the evidence for enhancement and suppression as mechanisms of sentence processing and clarify that the effects occur within sentences having a marked focus structure

    Personality Change as a Validation of the Bereiter Differential-Change Scales

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67011/2/10.1177_001316446802800112.pd

    Can an Optical Plankton Counter Produce Reasonable Estimates of Zooplankton Abundance and Biovolume in Water With High Detritus?

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    The Optical Plankton Counter (OPC) has been used in oceanic and fresh waters to estimate zooplankton abundance and biovolume. However, it is not clear whether the OPC can produce accurate estimates of zooplankton abundance and biovolume in waters with high detritus. In order to test the capability of the OPC to estimate zooplankton abundance and biovolume in Chesapeake Bay, two sets of laboratory experiments were conducted using water with high detritus concentrations collected from the upper Choptank estuary of Chesapeake Bay and laboratory cultured Artemia. Our results suggest that the OPC is able to produce accurate estimates of zooplankton biovolume after correcting for the influence of background detritus in all the detritus concentrations used, but accurate estimates of zooplankton abundance only in water with background detritus \u3c100 particles l-1. The relationship between light attenuation and OPC background particle concentrations provides a useful way to estimate OPC background particle concentrations when direct OPC background particle measurements are not available. Light attenuation corrected OPC particle abundance and particle volume gave accurate estimates of zooplankton abundance and biovolume. However, the accuracy of the corrected OPC measurements by the estimated background particle concentrations was not as high as the corrected OPC measurements by the direct background particle measurements

    A computational approach to implicit entities and events in text and discourse

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    In this paper we will focus on the notion of “implicit” or lexically unexpressed linguistic elements that are nonetheless necessary for a complete semantic interpretation of a text. We refer to “entities” and “events” because the recovery of the implicit material may affect all the modules of a system for semantic processing, from the grammatically guided components to the inferential and reasoning ones. Reference to the system GETARUNS offers one possible implementation of the algorithms and procedures needed to cope with the problem and enables us to deal with all the spectrum of phenomena. The paper will address at first the following three types of “implicit” entities and events: – the grammatical ones, as suggested by a linguistic theories like LFG or similar generative theories; – the semantic ones suggested in the FrameNet project, i.e. CNI, DNI, INI; – the pragmatic ones: here we will present a theory and an implementation for the recovery of implicit entities and events of (non-) standard implicatures. In particular we will show how the use of commonsense knowledge may fruitfully contribute to find relevant implied meanings. Last Implicit Entity only touched on, though for lack of space, is the Subject of Point of View, which is computed by Semantic Informational Structure and contributes the intended entity from whose point of view a given subjective statement is expressed

    A Survey of Ramp and Stair Use among Older Adults

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    Forty-three community-dwelling adults aged 57 to 95 participated in survey exploring characteristics of ramp use by older ambulant people. Twenty-three respondents said they ascended ramps instead of stairs most of the time, and 14 said they ascended ramps some of the time. Similar numbers were reported for descent. Overall, respondents felt less fatigued, less likely to trip, and more comfortable when using ramps rather than stairs for ascending one level. When descending one level, balance, tripping, and comfort were the strongest determinants of ramp use. Respondents indicated that descent was more problematic, particularly in regard to balance and tripping. The presence of handrails often determined the choice of route. Results from this survey provided the basis for an experiment evaluating the abilities of older people to traverse ramps of various slopes. The ADA Accessibility Guidelines implicitly assume that a ramp accommodates everyone. This study indicates that entrances should have both ramps and stairs.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Research Opportunities in Interdisciplinary Ground-Water Science

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    The U.S. Geological Survey (USGS) has a long-standing reputation for providing unbiased scientific leadership and excellence in the field of ground-water hydrology and geological research. This report provides a framework for continuing this scientific leadership by describing six interdisciplinary topics for research opportunities in ground-water science in the USGS. These topics build on recommendations of the National Research Council (2000) contained in the report, “Investigating Groundwater Systems on Regional and National Scales,” and emphasize research topics that would benefit from the integrated capabilities of all parts of the USGS. Understanding the relations between ground water and the geological characteristics of aquifers within which ground water resides, and the relation of ground water to surface-water resources and terrestrial and aquatic biota is increasingly important and presents a considerable opportunity to draw on expertise throughout the USGS, including the science disciplines of biology, geography, geology, and hydrology. The National Research Council (2000) also emphasizes that USGS regional and national assessments of ground-water resources should focus on aspects that foster the sustainability of the resource. The need for a comprehensive program addressing the sustainability of ground-water resources can be stated very concisely—we need enough ground water of good quality to sustain our lives, our economy, and our aquatic ecosystems. Although societal needs for high-quality, objective ground-water science are increasing, current funding for USGS regional ground-water programs is about 40 percent of the funding available 20–25 years ago. Given the current challenges of budgetary constraints, however, this report provides a flexible set of interrelated research topics that enhance the ability of the USGS to focus limited fiscal resources on developing ground-water science tools and methods that provide high-quality, objective scientific information

    Note and Comment

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    Safeguarding the Criminal Defendant - Every now and then a new attack is made somewhere in the United States upon the rule prohibiting comment before the jury upon the fact that the defendant in a criminal case has not testified as a witness in his own behalf. At the present time an effort of this kind is being made in the Michigan legislature, and the introduction of the bill drew quite a little storm of protest from the State press as a dangerous inroad upon our ancient guarantees of personal liberty and security. In fact, however, it directly touches nothing more ancient than a statutory privilege which dates from the year i86i. By the Public Acts of that year the disability of parties to actions to testify as witnesses in this State was removed, but it was expressly provided that defendants in criminal cases could not be compelled to testify, but might do so or not at their own pleasure. (Act No. 125, §2). In 1881 an amendment to this statute was passed providing, as to the defendant in a criminal case, that his neglect to testify shall not create any presumption against him, nor shall the court permit any reference or comment to be made to or upon such neglect. (Pub. Acts, 188I, No. 245). And this is the form it retains in the Judicature Act. (Ch. 17, §64)

    Effects of climate and irrigation on GRACE-based estimates of water storage changes in major US aquifers

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    Understanding climate and human impacts on water storage is critical for sustainable water-resources management. Here we assessed climate and human drivers of total water storage (TWS) variability from Gravity Recovery and Climate Experiment (GRACE) satellites compared with drought severity and irrigation water use in 14 major aquifers in the United States. Results show that long-term variability in TWS tracked by GRACE satellites is dominated by interannual variability in most of the 14 major US aquifers. Low TWS trends in the humid eastern U.S. are linked to low drought intensity. Although irrigation pumpage in the humid Mississippi Embayment aquifer exceeded that in the semi-arid California Central Valley, a surprising lack of TWS depletion in the Mississippi Embayment aquifer is attributed to extensive streamflow capture. Marked storage depletion in the semi-arid southwestern Central Valley and south-central High Plains totaled ∼90 km ^3 , about three times greater than the capacity of Lake Mead, the largest U.S. reservoir. Depletion in the Central Valley was driven by long-term droughts (⩽5 yr) amplified by switching from mostly surface water to groundwater irrigation. Low or slightly rising TWS trends in the northwestern (Columbia and Snake Basins) US are attributed to dampening drought impacts by mostly surface water irrigation. GRACE satellite data highlight synergies between climate and irrigation, resulting in little impact on TWS in the humid east, amplified TWS depletion in the semi-arid southwest and southcentral US, and dampened TWS deletion in the northwest and north central US Sustainable groundwater management benefits from conjunctive use of surface water and groundwater, inefficient surface water irrigation promoting groundwater recharge, efficient groundwater irrigation minimizing depletion, and increasing managed aquifer recharge. This study has important implications for sustainable water development in many regions globally

    Heart of Darkness: The Significance of the Zeptobarn Scale for Neutralino Direct Detection

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    The direct detection of dark matter through its elastic scattering off nucleons is among the most promising methods for establishing the particle identity of dark matter. The current bound on the spin-independent scattering cross section is sigma^SI < 10 zb for dark matter masses m_chi ~ 100 GeV, with improved sensitivities expected soon. We examine the implications of this progress for neutralino dark matter. We work in a supersymmetric framework well-suited to dark matter studies that is simple and transparent, with models defined in terms of four weak-scale parameters. We first show that robust constraints on electric dipole moments motivate large sfermion masses mtilde > 1 TeV, effectively decoupling squarks and sleptons from neutralino dark matter phenomenology. In this case, we find characteristic cross sections in the narrow range 1 zb 70 GeV. As sfermion masses are lowered to near their experimental limit mtilde ~ 400 GeV, the upper and lower limits of this range are extended, but only by factors of around two, and the lower limit is not significantly altered by relaxing many particle physics assumptions, varying the strange quark content of the nucleon, including the effects of galactic small-scale structure, or assuming other components of dark matter. Experiments are therefore rapidly entering the heart of dark matter-favored supersymmetry parameter space. If no signal is seen, supersymmetric models must contain some level of fine-tuning, and we identify and analyze several possibilities. Barring large cancellations, however, in a large and generic class of models, if thermal relic neutralinos are a significant component of dark matter, experiments will discover them as they probe down to the zeptobarn scale.Comment: 35 pages, 11 figures; v2: references added, figures extended to 2 TeV neutralino masses, XENON100 results included, published versio
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