512 research outputs found

    Autonomous power system intelligent diagnosis and control

    Get PDF
    The Autonomous Power System (APS) project at NASA Lewis Research Center is designed to demonstrate the abilities of integrated intelligent diagnosis, control, and scheduling techniques to space power distribution hardware. Knowledge-based software provides a robust method of control for highly complex space-based power systems that conventional methods do not allow. The project consists of three elements: the Autonomous Power Expert System (APEX) for fault diagnosis and control, the Autonomous Intelligent Power Scheduler (AIPS) to determine system configuration, and power hardware (Brassboard) to simulate a space based power system. The operation of the Autonomous Power System as a whole is described and the responsibilities of the three elements - APEX, AIPS, and Brassboard - are characterized. A discussion of the methodologies used in each element is provided. Future plans are discussed for the growth of the Autonomous Power System

    Do Experts Help or Hinder? An Empirical Examination of Experts and Expertise during Public Deliberation

    Get PDF
    We consider expertise in interaction during small group public deliberations. Taking communication as design, we analyze the intentional design of deliberative format using invited experts to support public discussions. Through discourse analysis of one expert’s interventions into the group discussion, we suggest how expertise might best contribute to public deliberation

    Crisis, Charisma and Consequences: Evidence from the 2004 US Presidential Election

    Get PDF
    We investigate how conditions of crisis affect perceptions of charisma and how these, in turn, affect blame attribution and self-sacrificial behavior. Our data are from a 2004 experimental study that preceded the U.S. presidential election, in which we manipulated concerns of a terrorist attack. The results show that those in the Crisis condition rated Bush higher on perceptions of charisma compared to those in the Good Times condition. The Crisis condition also directly and indirectly, via perceptions of charisma, affected whether Bush was blamed for failures in Iraq and our subjects’ willingness to sacrifice their personal resources for his candidacy

    Frequency Bin Entangled Photons

    Full text link
    A monochromatic laser pumping a parametric down conversion crystal generates frequency entangled photon pairs. We study this experimentally by addressing such frequency entangled photons at telecommunication wavelengths (around 1550 nm) with fiber optics components such as electro-optic phase modulators and narrow band frequency filters. The theory underlying our approach is developed by introducing the notion of frequency bin entanglement. Our results show that the phase modulators address coherently up to eleven frequency bins, leading to an interference pattern which can violate a Bell inequality adapted to our setup by more than five standard deviations.Comment: 10 pages, 4 figures (extended version

    Real-time measurements of dissipative solitons in a mode-locked fiber laser

    Full text link
    Dissipative solitons are remarkable localized states of a physical system that arise from the dynamical balance between nonlinearity, dispersion and environmental energy exchange. They are the most universal form of soliton that can exist in nature, and are seen in far-from-equilibrium systems in many fields including chemistry, biology, and physics. There has been particular interest in studying their properties in mode-locked lasers producing ultrashort light pulses, but experiments have been limited by the lack of convenient measurement techniques able to track the soliton evolution in real-time. Here, we use dispersive Fourier transform and time lens measurements to simultaneously measure real-time spectral and temporal evolution of dissipative solitons in a fiber laser as the turn-on dynamics pass through a transient unstable regime with complex break-up and collision dynamics before stabilizing to a regular mode-locked pulse train. Our measurements enable reconstruction of the soliton amplitude and phase and calculation of the corresponding complex-valued eigenvalue spectrum to provide further physical insight. These findings are significant in showing how real-time measurements can provide new perspectives into the ultrafast transient dynamics of complex systems.Comment: See also M. Narhi, P. Ryczkowski, C. Billet, G. Genty, J. M. Dudley, Ultrafast Simultaneous Real Time Spectral and Temporal Measurements of Fibre Laser Modelocking Dynamics, 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference, paper EE-3.5 (2017

    Implementing two-photon interference in the frequency domain with electro-optic phase modulators

    Full text link
    Frequency-entangled photons can be readily produced using parametric down-conversion. We have recently shown how such entanglement could be manipulated and measured using electro-optic phase modulators and narrow-band frequency filters, thereby leading to two-photon interference patterns in the frequency domain. Here we introduce new theoretical and experimental developments showing that this method is potentially a competitive platform for the realization of quantum communication protocols in standard telecommunication fibres. We derive a simple theoretical expression for the coincidence probabilities and use it to optimize a Bell inequality. Furthermore, we establish an equivalence between the entangled- photon scheme and a classical interference scheme. Our measurements of two-photon interference in the frequency domain yield raw visibilities in excess of 99%. We use our high quality setup to experimentally validate the theoretical predictions, and in particular we report a violation of the CH74 inequality by more than 18 standard deviations.Comment: 19 pages, 3 figure

    Engineering REST-Specific Synthetic PUF Proteins to Control Neuronal Gene Expression: A Combined Experimental and Computational Study

    Get PDF
    Regulation of gene transcription is an essential mechanism for differentiation and adaptation of organisms. A key actor in this regulation process is the repressor element 1 (RE1)-silencing transcription factor (REST), a transcriptional repressor that controls more than 2000 putative target genes, most of which are neuron-specific. With the purpose of modulating REST expression, we exploited synthetic, ad hoc designed, RNA binding proteins (RBPs) able to specifically target and dock to REST mRNA. Among the various families of RBPs, we focused on the Pumilio and FBF (PUF) proteins, present in all eukaryotic organisms and controlling a variety of cellular functions. Here, a combined experimental and computational approach was used to design and test 8- and 16-repeat PUF proteins specific for REST mRNA. We explored the conformational properties and atomic features of the PUF-RNA recognition code by Molecular Dynamics simulations. Biochemical assays revealed that the 8- and 16-repeat PUF-based variants specifically bind the endogenous REST mRNA without affecting its translational regulation. The data also indicate a key role of stacking residues in determining the binding specificity. The newly characterized REST-specific PUF-based constructs act as excellent RNA-binding modules and represent a versatile and functional platform to specifically target REST mRNA and modulate its endogenous expression

    The Porcellini test: a novel test for accurate diagnosis of posterior labral tears of the shoulder: comparative analysis with the established tests

    Get PDF
    Questions/purposes: Although the posterior labral tears of the shoulder are known for their disabling clinical course, especially in overhead athletes, no clinical test used in isolation can diagnose it accurately in the preoperative period. We wanted to: (1) introduce “Porcellini test” with its radiological verification furnishing the anatomical basis of its mechanism; (2) determine its accuracy; and (3) compare its accuracy with that of the other established tests for diagnosing posterior labral tears of the shoulder. Methods: To determine the anatomical basis, we initially performed radiological verification of our test. Then, we evaluated its accuracy in a retrospective case-controlled study on 310 consecutive patients who underwent shoulder arthroscopic procedures at our hospital between January 2013 and December 2013. All patients were examined preoperatively for Porcellini test, and the presence of posterior labral tear was confirmed on arthroscopy. Later, in a cohort study on 91 consecutive patients who underwent shoulder arthroscopic procedures, we compared its accuracy with O’Brien’s test, the Kim test, the Jerk test, and the Load and Shift test. The accuracy was interpreted in terms of sensitivity, specificity, and predictive values. Results: The radiological verification conferred the anatomical basis for the mechanism of the Porcellini test. This new test showed high accuracy for posterior labral tears with sensitivity of 100 %, specificity of 99.3 %, the positive and negative predictive values of 92.6 and 100 %, respectively. Also, it had superior accuracy results than every other test. The interexaminer reliability for all test results was found to be >0.80. Conclusions: We propose “Porcellini test” as a simple, accurate, reproducible, and reliable test for the preoperative diagnosis of posterior labral tears of shoulder

    Sleep Macrostructure and NREM Sleep Instability Analysis in Pediatric Developmental Coordination Disorder

    Get PDF
    Developmental Coordination Disorder (DCD) is considered to be abnormal motor skills learning, identified by clumsiness, slowness, and/or motor inaccuracy impairing the daily-life activities in all ages of life, in the absence of sensory, cognitive, or neurological deficits impairment. The present research focuses on studying DCD sleep structure and Cyclic Alternating Pattern (CAP) parameters with a full overnight polysomnography and to study the putative correlations between sleep architecture and CAP parameters with motor coordination skills. The study was a cross-sectional design involving 42 children (26M/16F; mean age 10.12 ± 1.98) selected as a DCD group compared with 79 children (49M/30F; mean age 9.94 ± 2.84) identified as typical (no-DCD) for motor ability and sleep macrostructural parameters according to the MABC-2 and polysomnographic (PSG) evaluations. The two groups (DCD and non-DCD) were similar for age (p = 0.715) and gender (p = 0.854). More significant differences in sleep architecture and CAP parameters were found between two groups and significant correlations were identified between sleep parameters and motor coordination skills in the study population. In conclusion, our data show relevant abnormalities in sleep structure of DCD children and suggest a role for rapid components of A phases on motor coordination development

    Race–Gender Differences in the Impact of History of Heavy Drinking on Current Alcohol Consumption during the Transition to Adulthood

    Get PDF
    American youth transitioning to adulthood consume more alcohol than in any other period of the life course. This high level of consumption can result in serious consequences, including lost productivity, death and disability, sexual assault, and addiction. Nevertheless, relatively little is known, especially by race and gender, about how prior history of heavy drinking (e.g., in late adolescence) impacts drinking in young adulthood. Utilizing data from the National Longitudinal Survey of Youth (1994-2004) for African Americans, Latinos, and Whites (N = 2,300), we found that Whites and Latinos drink more than African Americans, and men report drinking more than women. However, accounting for a history of heavy drinking introduces considerable variation in current drinking patterns by race–gender status. A history of heavy drinking more than doubles the number of drinks consumed by African American women, putting their drinking levels on par with African American men and White women and raising their level of drinking above Latinas. Further, African American women\u27s probability of heavy drinking becomes indistinguishable from that of African American men and White women, once accounting for a prior history of binge drinking. For Latinas with a history of heavy drinking, the probability of being a current binge drinker is equal to Latinos and White men and higher than African Americans and White women
    • …
    corecore