1,830 research outputs found

    Nuclear spin coherence in a quantum wire

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    We have observed millisecond-long coherent evolution of nuclear spins in a quantum wire at 1.2 K. Local, all-electrical manipulation of nuclear spins is achieved by dynamic nuclear polarization in the breakdown regime of the Integer Quantum Hall Effect combined with pulsed Nuclear Magnetic Resonance. The excitation thresholds for the breakdown are significantly smaller than what would be expected for our sample and the direction of the nuclear polarization can be controlled by the voltage bias. As a four-level spin system, the device is equivalent to two qubits.Comment: 5 pages, 5 figure

    Visualization methods for statistical analysis of microarray clusters

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    BACKGROUND: The most common method of identifying groups of functionally related genes in microarray data is to apply a clustering algorithm. However, it is impossible to determine which clustering algorithm is most appropriate to apply, and it is difficult to verify the results of any algorithm due to the lack of a gold-standard. Appropriate data visualization tools can aid this analysis process, but existing visualization methods do not specifically address this issue. RESULTS: We present several visualization techniques that incorporate meaningful statistics that are noise-robust for the purpose of analyzing the results of clustering algorithms on microarray data. This includes a rank-based visualization method that is more robust to noise, a difference display method to aid assessments of cluster quality and detection of outliers, and a projection of high dimensional data into a three dimensional space in order to examine relationships between clusters. Our methods are interactive and are dynamically linked together for comprehensive analysis. Further, our approach applies to both protein and gene expression microarrays, and our architecture is scalable for use on both desktop/laptop screens and large-scale display devices. This methodology is implemented in GeneVAnD (Genomic Visual ANalysis of Datasets) and is available at . CONCLUSION: Incorporating relevant statistical information into data visualizations is key for analysis of large biological datasets, particularly because of high levels of noise and the lack of a gold-standard for comparisons. We developed several new visualization techniques and demonstrated their effectiveness for evaluating cluster quality and relationships between clusters

    The Comparative Impacts of Social Justice Educational Methods on Political Participation, Civic Engagement, and Multicultural Activism

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    This cross-sectional, repeated measures, quasi-experimental study evaluates changes in college stu- dents’ commitment toward, and confidence in, political participation, civic engagement, and multi- cultural activism. Our sample (n = 653) consisted of college students in a Midwestern university who participated in one of three social justice education course types (service learning, intergroup dialogue, or lecture-based diversity classes) or in an “introduction to psychology” course (the non-intervention group). After completion of a social justice education course, students reported an increase in politi- cal participation and multicultural activism, whereas students enrolled in the non-intervention group reported no changes in these measures. Service learning course participants started and ended their course with the highest reported levels of political participation, civic engagement, and multicultural activism but did not demonstrate an increase in any of the three outcomes. Intergroup dialogue par- ticipants demonstrated increases in all three outcomes, while participants of lecture-based classes focusing on social justice issues demonstrated increases in political participation and multicultural activism, but not civic engagement. Our findings suggest that participation in social justice education courses is associated with increases in political participation and multicultural activism

    Patterns of prefrontal dysfunction in alcoholics with and without Korsakoff’s syndrome, patients with Parkinson’s disease, and patients with rupture and repair of the anterior communicating artery

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    This study compared patterns of frontal-lobe dysfunction in alcoholics with Korsakoff’s syndrome (KS: n = 9), non-Korsakoff alcoholics (AL: n = 28), patients with Parkinson’s disease (PD: n = 18), and patients with rupture and repair of the anterior communicating artery (ACoA: n = 4) relative to healthy non-neurological control (NC) participants (n = 70). The tests administered were sensitive to functions of dorsolateral prefrontal and orbito-frontal subsystems. Measures included perseverative errors on the Wisconsin Card Sorting Test (WCST-pe), errors on object alternation (OA), errors on Trails B, number of words generated on the Controlled Oral Word Association Test (COWAT), and number of categories completed on the WCST (WCST-cc). KS patients were as impaired as AL participants on orbitofrontal measures and, on dorsolateral prefrontal measures, were impaired relative to AL participants, whose performance did not differ from controls. Patients with PD also were impaired on tests of orbitofrontal and dorsolateral prefrontal functioning but to a lesser extent than the KS patients. Moreover, most of the PD deficits were driven by the impaired performance of patients whose initial symptoms were on the right side of the body. The ACoA patients were significantly impaired on tests of orbitofrontal but not dorsolateral prefrontal functioning relative to the control group. Together, the results confirm different patterns of frontal-system impairments in patient groups having compromised frontal lobe functioning consequent to varying etiologies

    Changes in Water Quality of Grand Lake St. Marys Watershed Following Implementation of a Distressed Watershed Rules Package

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    Grand Lake St. Marys watershed has drawn attention over the past decade as water quality issues resulting from nutrient loading have come to the forefront of public opinion, political concern, and scientific study. The objective of this study was to assess long-term changes in water quality (nutrient and sediment concentrations) following the distressed watershed rules package instituted in 2011. Since that time, a variety of rules (e.g., winter manure ban) and best management practices (cover crops, manure storage or transfers, buffers, etc.) have been implemented. We used a general linear model to assess variation in total suspended solids, particulate phosphorus, soluble reactive phosphorus (SRP), nitrate N, and total Kjeldahl nitrogen concentrations from daily Chickasaw Creek (drains ∼25% of watershed) samples spanning 2008 to 2016. Parameters were related to flow (higher values during high flows), timing (lower values during winter months), and the implementation of the distressed watershed rules package (lower values following implementation). Overall, reductions following the distressed designation for all parameters ranged from 5 to 35% during medium and high flow periods (with exception of SRP). Reductions were even more pronounced during winter months covered by the manure ban, where all parameters (including SRP) exhibited decreases at medium and high flows between 20 and 60%. While the reductions seen in this study are significant, concentrations are still highly elevated and continue to be a problem. We are optimistic that this study will serve to inform future management in the region and elsewhere

    Computing Zernike polynomials of arbitrary degree using the discrete Fourier transform

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    The conventional representation of Zernike polynomials R_n^m(rho) gives unacceptable results for large values of the degree n. We present an algorithm for the computation of Zernike polynomials of arbitrary degree n. The algorithm has the form of a discrete cosine transform which comes with advantages over other methods in terms of computation time, accuracy and transparancy. As an application we consider the effect of NA-scaling on the lower-order aberrations of an optical system in the presence of a very high order aberration
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