1,828 research outputs found

    Affective Polarization: Does Political Affiliation Affect An Applicant's Hireability?

    Get PDF
    The present study seeks to examine the role that political affective polarization (A.P.) may play in an employment setting: specifically perceptions of a job candidate, hiring decisions, and expectations for that potential new employee. Participants were randomly assigned to read one of three comparable resumes: one signaling Democrat partisanship, a second signaling Republican partisanship, and a third neutral resume that did not signal any partisanship. Participants were asked about their perceptions of the job applicant and the standards they would set if the fabricated job applicant were hired. A statistically significant relationship was found between A.P. and the performance standards set for the job applicant. The theoretical and practical implications of this result are discussed. In addition, the present study highlights the need to study A.P. outside of voting behaviors, and instead, look at other domains of life

    The Two Types of Society: Computationally Revealing Recurrent Social Formations and Their Evolutionary Trajectories

    Get PDF
    Comparative social science has a long history of attempts to classify societies and cultures in terms of shared characteristics. However, only recently has it become feasible to conduct quantitative analysis of large historical datasets to mathematically approach the study of social complexity and classify shared societal characteristics. Such methods have the potential to identify recurrent social formations in human societies and contribute to social evolutionary theory. However, in order to achieve this potential, repeated studies are needed to assess the robustness of results to changing methods and data sets. Using an improved derivative of the Seshat: Global History Databank, we perform a clustering analysis of 271 past societies from sampling points across the globe to study plausible categorizations inherent in the data. Analysis indicates that the best fit to Seshat data is five subclusters existing as part of two clearly delineated superclusters (that is, two broad “types” of society in terms of social-ecological configuration). Our results add weight to the idea that human societies form recurrent social formations by replicating previous studies with different methods and data. Our results also contribute nuance to previously established measures of social complexity, illustrate diverse trajectories of change, and shed further light on the finite bounds of human social diversity

    Using imprecise continuous time Markov chains for assessing the reliability of power networks with common cause failure and non-immediate repair.

    Get PDF
    We explore how imprecise continuous time Markov chains can improve traditional reliability models based on precise continuous time Markov chains. Specifically, we analyse the reliability of power networks under very weak statistical assumptions, explicitly accounting for non-stationary failure and repair rates and the limited accuracy by which common cause failure rates can be estimated. Bounds on typical quantities of interest are derived, namely the expected time spent in system failure state, as well as the expected number of transitions to that state. A worked numerical example demonstrates the theoretical techniques described. Interestingly, the number of iterations required for convergence is observed to be much lower than current theoretical bounds

    Cryogenic Propellant Feed System Analytical Tool Development

    Get PDF
    The Propulsion Systems Branch at NASA s Lyndon B. Johnson Space Center (JSC) has developed a parametric analytical tool to address the need to rapidly predict heat leak into propellant distribution lines based on insulation type, installation technique, line supports, penetrations, and instrumentation. The Propellant Feed System Analytical Tool (PFSAT) will also determine the optimum orifice diameter for an optional thermodynamic vent system (TVS) to counteract heat leak into the feed line and ensure temperature constraints at the end of the feed line are met. PFSAT was developed primarily using Fortran 90 code because of its number crunching power and the capability to directly access real fluid property subroutines in the Reference Fluid Thermodynamic and Transport Properties (REFPROP) Database developed by NIST. A Microsoft Excel front end user interface was implemented to provide convenient portability of PFSAT among a wide variety of potential users and its ability to utilize a user-friendly graphical user interface (GUI) developed in Visual Basic for Applications (VBA). The focus of PFSAT is on-orbit reaction control systems and orbital maneuvering systems, but it may be used to predict heat leak into ground-based transfer lines as well. PFSAT is expected to be used for rapid initial design of cryogenic propellant distribution lines and thermodynamic vent systems. Once validated, PFSAT will support concept trades for a variety of cryogenic fluid transfer systems on spacecraft, including planetary landers, transfer vehicles, and propellant depots, as well as surface-based transfer systems. The details of the development of PFSAT, its user interface, and the program structure will be presented

    Optimized kinematics enable both aerial and aquatic propulsion from a single three-dimensional flapping wing

    Get PDF
    Flapping wings in nature demonstrate a large force envelope, with capabilities far beyond the traditional limits of static airfoil section coefficients. Puffins, murres, and other auks particularly showcase this effect, as they are able to generate both enough thrust to swim and enough lift to fly, using the same wing, purely by changing the wing motion trajectory. The wing trajectory is therefore an additional design criterion to be optimized along with traditional aircraft parameters and could open the door to dual aerial-aquatic robotic vehicles. In this paper we showcase one realization of a three-dimensional flapping-wing actuation system that reproduces the force coefficients necessary for dual aerial-aquatic flight. The wing apparatus oscillates by the root and employs an active upstream and downstream sweep degree of freedom. We analyze two types of motions in detail: aerial motions where the wing tip moves upstream during the power stroke of each flapping cycle and aquatic motions where the wing tip moves downstream during the power stroke. We design these aerial and aquatic flapping-wing trajectories using an experiment-coupled optimization routine, allowing control of the unsteady forces throughout each flapping cycle. Additionally, we elucidate the wakes of these complex wing trajectories using dye visualization, correlating the wake vortex structures with simultaneous experiment force measurements. After optimization, the wing trajectories generate the large force envelope necessary for propulsion in both fluid media and furthermore demonstrate improved control over the unsteady wake

    The P450 CYP6Z1 confers carbamate/pyrethroid cross-resistance in a major African malaria vector beside a novel carbamate-insensitive N485I acetylcholinesterase-1 mutation

    Get PDF
    Carbamates are increasingly used for vector control notably in areas with pyrethroid resistance. However, a cross-resistance between these insecticides in major malaria vectors such as Anopheles funestus could severely limit available resistance management options. Unfortunately, the molecular basis of such cross-resistance remains uncharacterized in An. funestus, preventing effective resistance management. Here, using a genome-wide transcription profiling, we revealed that metabolic resistance through up-regulation of cytochrome P450 genes is driving carbamate resistance. The P450s CYP6P9a, CYP6P9b and CYP6Z1 were the most up-regulated detoxification genes in the multiple resistant mosquitoes. However, in silico docking simulations predicted CYP6Z1 to metabolise both pyrethroids and carbamates, whereas CYP6P9a and CYP6P9b were predicted to metabolise only the pyrethroids. Using recombinant enzyme metabolism and inhibition assays we demonstrated that CYP6Z1 metabolizes bendiocarb and pyrethroids, whereas CYP6P9a and CYP6P9b metabolise only the pyrethroids. Other up-regulated gene families in resistant mosquitoes included several cuticular protein genes suggesting a possible reduced penetration resistance mechanism. Investigation of the target-site resistance in acetylcholinesterase 1 (ace-1) gene detected and established the association between the new N485I mutation and bendiocarb resistance (Odds ratio 7.3; P<0.0001). The detection of multiple haplotypes in single mosquitoes after cloning suggested the duplication of ace-1. A TaqMan genotyping of the N485I in nine countries revealed that the mutation is located only in Southern Africa with frequency of 10-15% suggesting its recent occurrence. These findings will help in monitoring the spread and evolution of carbamate resistance and improve the design of effective resistance management strategies to control this malaria vector

    Radial fingering in a Hele-Shaw cell: a weakly nonlinear analysis

    Full text link
    The Saffman-Taylor viscous fingering instability occurs when a less viscous fluid displaces a more viscous one between narrowly spaced parallel plates in a Hele-Shaw cell. Experiments in radial flow geometry form fan-like patterns, in which fingers of different lengths compete, spread and split. Our weakly nonlinear analysis of the instability predicts these phenomena, which are beyond the scope of linear stability theory. Finger competition arises through enhanced growth of sub-harmonic perturbations, while spreading and splitting occur through the growth of harmonic modes. Nonlinear mode-coupling enhances the growth of these perturbations with appropriate relative phases, as we demonstrate through a symmetry analysis of the mode coupling equations. We contrast mode coupling in radial flow with rectangular flow geometry.Comment: 36 pages, 5 figures, Latex, added references, to appear in Physica D (1998

    Phytochemical characterization of Tabernanthe iboga root bark and its effects on dysfunctional metabolism and cognitive performance in high-fat-fed C57BL/6J mice

    Get PDF
    Preparations of the root bark of Tabernanthe iboga have long been used in Central and West African traditional medicine to combat fatigue, as a neuro-stimulant in rituals, and for treatment of diabetes. The principal alkaloid of T. iboga, ibogaine, has attracted attention in many countries around the world for providing relief for opioid craving in drug addicts. Using a plant metabolomics approach, we detected five phenolic compounds, including 3- O-caffeoylquinic acid, and 30 alkaloids, seven of which were previously reported from T. iboga root bark. Following a report that iboga extracts contain insulinotropic agents, we aimed to determine the potential alleviating effects of the water extract of iboga root bark on high-fat diet (HFD)-induced hyperglycemia as well as its effects on cognitive function in male C57BL/6J mice. Feeding a HFD to mice for 10 weeks produced manifestations of metabolic syndrome such as increased body weight and increased plasma levels of glucose, triacylglycerols, total cholesterol, LDL-cholesterol, insulin, leptin, and pro-inflammatory mediators (IL-6, MCP-1, ICAM-1), as compared to mice fed a low-fat diet (LFD). Supplementation of HFD with iboga extract at ibogaine doses of 0.83 (low) and 2.07 (high) mg/kg/day did not improve these HFD-induced metabolic effects except for a reduction of plasma MCP-1 in the low dose group, indicative of an anti-inflammatory effect. When the HFD mice were tested in the water maze, the high-dose iboga extract caused hippocampus-dependent impairments in spatial learning and memory, as compared to mice receiving only a HFD.Peer reviewedFinal Published versio

    eleanor: An open-source tool for extracting light curves from the TESS Full-Frame Images

    Get PDF
    During its two year prime mission the Transiting Exoplanet Survey Satellite (TESS) will perform a time-series photometric survey covering over 80% of the sky. This survey comprises observations of 26 24 x 96 degree sectors that are each monitored continuously for approximately 27 days. The main goal of TESS is to find transiting planets around 200,000 pre-selected stars for which fixed aperture photometry is recorded every two minutes. However, TESS is also recording and delivering Full-Frame Images (FFIs) of each detector at a 30 minute cadence. We have created an open-source tool, eleanor, to produce light curves for objects in the TESS FFIs. Here, we describe the methods used in eleanor to produce light curves that are optimized for planet searches. The tool performs background subtraction, aperture and PSF photometry, decorrelation of instrument systematics, and cotrending using principal component analysis. We recover known transiting exoplanets in the FFIs to validate the pipeline and perform a limited search for new planet candidates in Sector 1. Our tests indicate that eleanor produces light curves with significantly less scatter than other tools that have been used in the literature. Cadence-stacked images, and raw and detrended eleanor light curves for each analyzed star will be hosted on MAST, with planet candidates on ExoFOP-TESS as Community TESS Objects of Interest (CTOIs). This work confirms the promise that the TESS FFIs will enable the detection of thousands of new exoplanets and a broad range of time domain astrophysics.Comment: 21 pages, 13 figures, 2 tables, Accepted to PAS
    • …
    corecore