5,855 research outputs found

    Peer Neighborhood Mechanisms: A Framework for Mechanism Generalization

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    Peer prediction incentive mechanisms for crowdsourcing are generally limited to eliciting samples from categorical distributions. Prior work on extending peer prediction to arbitrary distributions has largely relied on assumptions on the structures of the distributions or known properties of the data providers. We introduce a novel class of incentive mechanisms that extend peer prediction mechanisms to arbitrary distributions by replacing the notion of an exact match with a concept of neighborhood matching. We present conditions on the belief updates of the data providers that guarantee incentive-compatibility for rational data providers, and admit a broad class of possible reasonable updates.Comment: Full paper with technical Appendix to reference from AAAI conference pape

    The Halo Occupation Distribution of X-ray-Bright Active Galactic Nuclei: A Comparison with Luminous Quasars

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    We perform halo occupation distribution (HOD) modeling of the projected two-point correlation function (2PCF) of high-redshift (z~1.2) X-ray-bright active galactic nuclei (AGN) in the XMM-COSMOS field measured by Allevato et al. The HOD parameterization is based on low-luminosity AGN in cosmological simulations. At the median redshift of z~1.2, we derive a median mass of (1.02+0.21/-0.23)x10^{13} Msun/h for halos hosting central AGN and an upper limit of ~10% on the AGN satellite fraction. Our modeling results indicate (at the 2.5-sigma level) that X-ray AGN reside in more massive halos compared to more bolometrically luminous, optically-selected quasars at similar redshift. The modeling also yields constraints on the duty cycle of the X-ray AGN, and we find that at z~1.2 the average duration of the X-ray AGN phase is two orders of magnitude longer than that of the quasar phase. Our inferred mean occupation function of X-ray AGN is similar to recent empirical measurements with a group catalog and suggests that AGN halo occupancy increases with increasing halo mass. We project the XMM-COSMOS 2PCF measurements to forecast the required survey parameters needed in future AGN clustering studies to enable higher precision HOD constraints and determinations of key physical parameters like the satellite fraction and duty cycle. We find that N^{2}/A~5x10^{6} deg^{-2} (with N the number of AGN in a survey area of A deg^{2}) is sufficient to constrain the HOD parameters at the 10% level, which is easily achievable by upcoming and proposed X-ray surveys.Comment: 11 pages, 4 figures, accepted in Ap

    Organizational Design for Spill Containment in Deepwater Drilling Operations in the Gulf of Mexico: Assessment of the Marine Well Containment Company (MWCC)

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    The Deepwater Horizon oil spill in the Gulf of Mexico in April 2010 led to the deaths of 11 workers, a six-month moratorium on deepwater drilling in the Gulf, and nearly three months of massive engineering and logistics efforts to stop the spill. The series of failures before the well was finally capped and the spill contained revealed an inability to deal effectively with a well in deepwater and ultradeepwater. Ensuring that containment capabilities are adequate for drilling operations at these depths is therefore a salient challenge for government and industry. In this paper we assess the Marine Well Containment Company (MWCC), a consortium aimed at designing and building a system capable of containing future deepwater spills in the Gulf. We also consider alternatives for long-term readiness for deepwater spill containment. We focus on the roles of liability and regulation as determinants of readiness and the adequacy of incentives for technological innovation in oil spill containment technology to keep pace with advances in deepwater drilling capability. Liability and regulation can significantly influence the strength of these incentives. In addition, we discuss appropriate governance structure as a major determinant of the effectiveness of MWCC.oil spill, containment, industry R&D, liability, regulation, governance, innovation

    Fear extinction across development: The involvement of the medial prefrontal cortex as assessed by temporary inactivation and immunohistochemistry

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    Extinction in adult animals, including humans, appears to involve the medial prefrontal cortex (mPFC). However, the role of mPFC in extinction across development has not yet been studied. Given several recent demonstrations of developmental differences in extinction of conditioned fear at a behavioral level, different neural circuitries may mediate fear extinction across development. In all experiments, noise conditioned stimulus (CS) and shock unconditioned stimulus (US) were used. In experiment 1A, temporary unilateral inactivation of the mPFC during extinction training impaired long-term extinction the following day in postnatal day 24 (P24) rats but not in P17 rats. In experiment 1B, bilateral inactivation of them PFC again failed to disrupt long-term extinction in P17 rats. In experiment 2, extinction training increased phosphorylated mitogen-activated protein kinase (pMAPK) in the mPFC for P24 rats but not for P17 rats, whereas rats of both ages displayed elevated pMAPK in the amygdala. Across both ages, "not trained," "reactivated, " and "no extinction" control groups expressed very low numbers of pMAPK immunoreactive (IR) neurons across both neural structures. This result indicates that the mere conditioning experience, the exposure to the CS, or the expression of CS-elicited fear in and of itself is not sufficient to explain the observed increase in pMAPK-IR neurons in them PFC and/or the amygdala after extinction. Together, these findings show that extinction in P17 rats does not involve the mPFC, which has important theoretical and clinical implications for the treatment of anxiety disorders in humans

    Fear extinction across development: The involvement of the medial prefrontal cortex as assessed by temporary inactivation and immunohistochemistry

    Get PDF
    Extinction in adult animals, including humans, appears to involve the medial prefrontal cortex (mPFC). However, the role of mPFC in extinction across development has not yet been studied. Given several recent demonstrations of developmental differences in extinction of conditioned fear at a behavioral level, different neural circuitries may mediate fear extinction across development. In all experiments, noise conditioned stimulus (CS) and shock unconditioned stimulus (US) were used. In experiment 1A, temporary unilateral inactivation of the mPFC during extinction training impaired long-term extinction the following day in postnatal day 24 (P24) rats but not in P17 rats. In experiment 1B, bilateral inactivation of them PFC again failed to disrupt long-term extinction in P17 rats. In experiment 2, extinction training increased phosphorylated mitogen-activated protein kinase (pMAPK) in the mPFC for P24 rats but not for P17 rats, whereas rats of both ages displayed elevated pMAPK in the amygdala. Across both ages, "not trained," "reactivated, " and "no extinction" control groups expressed very low numbers of pMAPK immunoreactive (IR) neurons across both neural structures. This result indicates that the mere conditioning experience, the exposure to the CS, or the expression of CS-elicited fear in and of itself is not sufficient to explain the observed increase in pMAPK-IR neurons in them PFC and/or the amygdala after extinction. Together, these findings show that extinction in P17 rats does not involve the mPFC, which has important theoretical and clinical implications for the treatment of anxiety disorders in humans

    Alleviating Linear Ecological Bias and Optimal Design with Subsample Data

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    In this paper, we illustrate that combining ecological data with subsample data in situations in which a linear model is appropriate provides three main benefits. First, by including the individual level subsample data, the biases associated with linear ecological inference can be eliminated. Second, by supplementing the subsample data with ecological data, the information about parameters will be increased. Third, we can use readily available ecological data to design optimal subsampling schemes, so as to further increase the information about parameters. We present an application of this methodology to the classic problem of estimating the effect of a college degree on wages. We show that combining ecological data with subsample data provides precise estimates of this value, and that optimal subsampling schemes (conditional on the ecological data) can provide good precision with only a fraction of the observations

    The 'British Policy Style' and Mental Health: Beyond the Headlines

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    Recent Mental Health Acts provide evidence of diverging UK and Scottish government policy styles. The UK legislative process lasted almost ten years following attempts by ministers to impose decisions and an unprecedented level of sustained opposition from interest groups. In contrast, the consultation process in Scotland was consensual, producing high levels of stakeholder ‘ownership'. This article considers two narratives on the generalisability of this experience. The first suggests that it confirms a ‘majoritarian' British policy style, based on the centralisation of power afforded by a first-past-the-post electoral system (Lijphart, 1999). Diverging styles are likely because widespread hopes for consensus politics in the devolved territories have been underpinned by proportional representation. The second suggests that most policy-making is consensual, based on the diffusion of power across policy sectors and the ‘logic of consultation' between governments and interest groups (Jordan and Richardson, 1982). The legislative process deviated temporarily from the ‘normal' British policy style which is more apparent when we consider mental health policy as a whole. Overall, the evidence points to more than one picture of British styles; it suggests that broad conclusions on ‘majoritarian' systems must be qualified by detailed empirical investigation
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