2,738 research outputs found

    Effects of Data Imputation Methods on Data Missingness in Data Mining

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    The purpose of this paper is to study theeffectiveness of data imputation methods in dealingwith data missingness in the data mining phase ofknowledge discovery in Database (KDD). Theapplication of data mining techniques without carefulconsideration of missing data can result into biasedresults and skewed conclusions. This research exploresthe impact of data missingness at various levels in KDDmodels employing neural networks as the primary datamining algorithm. Four of the most commonly utilizeddata imputation methods - Case Deletion, MeanSubstitution, Regression Imputation, and MultipleImputation were evalutated using Root Mean Square(RMS) Values, ANOVA Testing, T-tests, and Tukey’sHonestly Significant Difference Test to assess thedifferences of performance levels between variousKnowledge Discovery and Neural Network Models,both in the presence and absence of Missing Data

    Contradictory Evidence on Wave Forcing of Tropical Upwelling in the Brewer-Dobson Circulation - A Suggested Resolution

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    ERA-40 data are analyzed to demonstrate that wave forcing at lower latitudes plays a crucial role in driving the tropical upwelling portion of the Brewer-Dobson circulation. It is shown that subtropical wave forcing is correlated with tropical upwelling on both intraseasonal and interannual time scales when transient waves are taken into account, and that tropical wave forcing exerts its influence on tropical upwelling via its body force on the zonal mean flow

    Carbon isotope ratios of amylose, amylopectin and mutant starches

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    Carbon isotope ratios (expressed as δ13C values) were determined for various sources of starch and the starch fractions amylose and amylopectin. The δ13C values of amylose were consistently less negative, 0.4–2.3 ‰, than those of amylopectin in kernal starch from maize (Zea mays) and barley (Hordeum vulgare) and in tuber starch from potato (Solanum tuberosum). Kernel starch isolated from the maize mutants wx1 and ae1, with known genetic lesions in the starch biosynthetic pathway, also showed significant differences in δ13C values. Collectively, these results suggest that variation in carbon isotope ratios in the amylose and amylopectin components of starch may be attributed to isotopic discrimination by the enzymes involved in starch biosynthesis

    Dipolar recoupling in solid state NMR by phase alternating pulse sequences

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    We describe some new developments in the methodology of making heteronuclear and homonuclear recoupling experiments in solid state NMR insensitive to rf-inhomogeneity by phase alternating the irradiation on the spin system every rotor period. By incorporating delays of half rotor periods in the pulse sequences, these phase alternating experiments can be made Îł encoded. The proposed methodology is conceptually different from the standard methods of making recoupling experiments robust by the use of ramps and adiabatic pulses in the recoupling periods. We show how the concept of phase alternation can be incorporated in the design of homonuclear recoupling experiments that are both insensitive to chemical shift dispersion and rf-inhomogeneity.United States. Office of Naval Research (38A-1077404)United States. Air Force Office of Scientific Research (FA9550-05-1-0443)National Science Foundation (U.S.) (0724057)National Institute for Biomedical Imaging and Bioengineering (U.S.) (Grant EB003151)National Institute for Biomedical Imaging and Bioengineering (U.S.) (Grant EB002026

    Development and Testing of a Decision Aid on Goals of Care for Advanced Dementia

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    Objectives—Decision aids are effective to improve decision-making, yet they are rarely tested in nursing homes (NHs). Study objectives were to 1) examine the feasibility of a Goals of Care (GOC) decision aid for surrogate decision-makers (SDMs) of persons with dementia; and 2) test its effect on quality of communication and decision-making. Design—Pre-post intervention to test a GOC decision aid intervention for SDMs for persons with dementia in NHs. Investigators collected data from reviews of resident health records and interviews with SDMs at baseline and 3-month follow up. Setting—Two NHs in North Carolina. Participants—18 residents who were over 65 years of age, had moderate to severe dementia on the Global Deterioration Scale (GDS=5,6,7), and an English-speaking surrogate decision-maker. Intervention—1) GOC Decision Aid video viewed by the SDM, and 2) a structured care plan meeting between the SDM and interdisciplinary NH team. Measurements—Surrogate knowledge, quality of communication with health care providers, surrogate-provider concordance on goals of care, and palliative care domains addressed in the care plan. Results—89% of the SDMs thought the decision aid was relevant to their needs. After viewing the video decision aid, SDMs increased the number of correct responses on knowledge-based questions (12.5 vs 14.2, P<.001). At 3 months they reported improved quality of communication scores (6.1 vs 6.8, P=.01) and improved concordance on primary goal of care with nursing home team (50% vs 8%, P=.003). The number of palliative care domains addressed in the care plan increased (1.8 vs 4.3, P<.001). Conclusion—The decision-support intervention piloted in this study was feasible and relevant for surrogate decision-makers of persons with advanced dementia in nursing homes, and it improved quality of communication between SDM and NH providers. A larger randomized clinical trial is underway to provide further evidence of the effects of this decision aid intervention

    Training the polarization in integrated La0.15Bi0.85FeO3-based devices

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    The functionalities of BiFeO3-based magnetoelectric multiferroic heterostructures rely on the controlled manipulation of their ferroelectric domains and of the corresponding net in-plane polarization, as this aspect guides the voltage-controlled magnetic switching. Chemical substitution has emerged as a key to push the energy dissipation of the BiFeO3 into the attojoule range but appears to result in a disordered domain configuration. Using non-invasive optical second-harmonic generation on heavily La-substituted BiFeO3 films, it is shown that a weak net in-plane polarization remains imprinted in the pristine films despite the apparent domain disorder. It is found that this ingrained net in-plane polarization can be trained with out-of-plane electric fields compatible with applications. Operando studies on capacitor heterostructures treated in this way show the full restoration of the domain configuration of pristine BiFeO3 along with a giant net in-plane polarization enhancement. Thus, the experiments reveal a surprising robustness of the net in-plane polarization of BiFeO3 against chemical modification, an important criterion in ongoing attempts to integrate magnetoelectric materials into energy-efficient device

    Criminal Justice and Suicide Outcomes with Indiana's Risk-Based Gun Seizure Law

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    This article examines the application and effectiveness of a 2006 Indiana law designed to prevent gun violence by authorizing police officers to separate firearms from persons who present imminent or future risk of injury to self or others, or display a propensity for violent or emotionally unstable conduct. A court hearing is held to determine ongoing risk in these cases; a judge decides whether to return the seized firearms or retain them for up to five years. The study examines the frequency of criminal arrest as well as suicide outcomes for 395 gun-removal actions in Indiana. Fourteen individuals (3.5%) died from suicide, seven (1.8%) using a firearm. The study population's annualized suicide rate was about 31 times higher than that of the general adult population in Indiana, demonstrating that the law is being applied to a population genuinely at high risk. By extrapolating information on the case fatality rate for different methods of suicide, we calculated that one life was saved for every 10 gun-removal actions, similar to results of a previous study in Connecticut. Perspectives from key stakeholders are also presented along with implications for gun policy reform and implementation

    Evaluation and QTL mapping of phosphorus concentration in soybean seed

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    Phosphorus (P) is an essential macronutrient required for many biological and metabolic plant functions. Phosphate is the form of P used by plants. Reducing the amount of P in the seed can further aide breeding efforts to reduce the amount of P released into the environment due to the indigestibility of the complexes formed with metal ions. Analysis of the variation of phosphorus concentration in soybean seed under non-stressed conditions revealed that phosphorus ranged from 3,948.1 to 5,695.8 ÎĽg/g total phosphorous (TP) in combined years. The averages for independent years were significantly different from one another. Quantitative trait loci (QTL) analysis of TP was performed to identify candidate gene(s) that is (are) involved in P accumulation in soybean seed. One putative QTL region was identified on chromosome 12 in the combined data that contained a phosphate transporter gene. Two additional suggestive QTL were identified on chromosomes 7 and 17 with chromosome 7 having both a phosphate transport gene and a ZIP transporter gene in the region of the QTL. There were additional genes in these regions that are involved in phosphate metabolism and transport

    Using CFD as a Rocket Injector Design Tool: Recent Progress at Marshall Space Flight Center

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    New programs are forcing American propulsion system designers into unfamiliar territory. For instance, industry s answer to the cost and reliability goals set out by the Next Generation Launch Technology Program are engine concepts based on the Oxygen- Rich Staged Combustion Cycle. Historical injector design tools are not well suited for this new task. The empirical correlations do not apply directly to the injector concepts associated with the ORSC cycle. These legacy tools focus primarily on performance with environment evaluation a secondary objective. Additionally, the environmental capability of these tools is usually one-dimensional while the actual environments are at least two- and often three-dimensional. CFD has the potential to calculate performance and multi-dimensional environments but its use in the injector design process has been retarded by long solution turnaround times and insufficient demonstrated accuracy. This paper has documented the parallel paths of program support and technology development currently employed at Marshall Space Flight Center in an effort to move CFD to the forefront of injector design. MSFC has established a long-term goal for use of CFD for combustion devices design. The work on injector design is the heart of that vision and the Combustion Devices CFD Simulation Capability Roadmap that focuses the vision. The SRL concept, combining solution fidelity, robustness and accuracy, has been established as a quantitative gauge of current and desired capability. Three examples of current injector analysis for program support have been presented and discussed. These examples are used to establish the current capability at MSFC for these problems. Shortcomings identified from this experience are being used as inputs to the Roadmap process. The SRL evaluation identified lack of demonstrated solution accuracy as a major issue. Accordingly, the MSFC view of code validation and current MSFC-funded validation efforts were discussed in some detail. The objectives of each effort were noted. Issues relative to code validation for injector design were discussed in some detail. The requirement for CFD support during the design of the experiment was noted and discussed in terms of instrumentation placement and experimental rig uncertainty. In conclusion, MSFC has made significant progress in the last two years in advancing CFD toward the goal of application to injector design. A parallel effort focused on program support and technology development via the SCIT Task have enabled the progress
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