1,635 research outputs found

    Biologically Inspired Feedback Design for Drosophila Flight

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    We use a biologically motivated model of the Drosophila's flight mechanics and sensor processing to design a feedback control scheme to regulate forward flight. The model used for insect flight is the grand unified fly (GUF) [3] simulation consisting of rigid body kinematics, aerodynamic forces and moments, sensory systems, and a 3D environment model. We seek to design a control algorithm that will convert the sensory signals into proper wing beat commands to regulate forward flight. Modulating the wing beat frequency and mean stroke angle produces changes in the flight envelope. The sensory signals consist of estimates of rotational velocity from the haltere organs and translational velocity estimates from visual elementary motion detectors (EMD's) and matched retinal velocity filters. The controller is designed based on a longitudinal model of the flight dynamics. Feedforward commands are generated based on a desired forward velocity. The dynamics are linearized around this operating point and a feedback controller designed to correct deviations from the operating point. The control algorithm is implemented in the GUF simulator and achieves the desired tracking of the forward reference velocities and exhibits biologically realistic responses

    Digging Deeper into Hardin\u27s Pasture: The Complex Institutional Structure of The Tragedy of the Commons

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    The institutional and ecological structure of Hardin’s “tragedy of the commons” appears deceptively simple: the open-access pasture eventually will be overexploited and degraded unless (i) it is privatized, (ii) the government regulates access and use, or (iii) the users themselves impose a common-property regime to regulate their own access and use. In this paper, we argue that the institutional structure of the “Herder Problem” (as it is known to game theorists) is far more complicated than it is usually portrayed. Specifically, it is not just about the pasture. It is equally about the grass that grows on the pasture and the cattle that consume the grass. Even Elinor Ostrom — a scholar known for embracing complexity — presented an overly simplistic portrayal of Hardin’s open-access pasture when she described its governance system as a null set of institutions. A more careful assessment of the situation, employing Ostrom’s Social-Ecological System (SES) framework, broadens the focus from the res communes omnium pasture to incorporate the res nullius grass that grows upon it and the res private cattle grazing there. The “tragedy” arises from the combination and interactions of the resources and their governing institutions, not just from the absence of property in the pasture. If the grass was not subject to appropriation, the cattle were not privately owned, or if property- and contract-enforcement institutions supporting market exchange were absent, the “tragedy of the commons” probably would not arise regardless of the pasture’s open-access status

    Digging Deeper into Hardin\u27s Pasture: The Complex Institutional Structure of The Tragedy of the Commons

    Get PDF
    The institutional and ecological structure of Hardin’s “tragedy of the commons” appears deceptively simple: the open-access pasture eventually will be overexploited and degraded unless (i) it is privatized, (ii) the government regulates access and use, or (iii) the users themselves impose a common-property regime to regulate their own access and use. In this paper, we argue that the institutional structure of the “Herder Problem” (as it is known to game theorists) is far more complicated than it is usually portrayed. Specifically, it is not just about the pasture. It is equally about the grass that grows on the pasture and the cattle that consume the grass. Even Elinor Ostrom — a scholar known for embracing complexity — presented an overly simplistic portrayal of Hardin’s open-access pasture when she described its governance system as a null set of institutions. A more careful assessment of the situation, employing Ostrom’s Social-Ecological System (SES) framework, broadens the focus from the res communes omnium pasture to incorporate the res nullius grass that grows upon it and the res private cattle grazing there. The “tragedy” arises from the combination and interactions of the resources and their governing institutions, not just from the absence of property in the pasture. If the grass was not subject to appropriation, the cattle were not privately owned, or if property- and contract-enforcement institutions supporting market exchange were absent, the “tragedy of the commons” probably would not arise regardless of the pasture’s open-access status

    Convergent Validity and Test-Retest Reliability of the Preschool Behavioral and Emotional Behavior Rating Scale: Parents as Respondents

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    A number of professional organizations have called on the need for valid and reliable assessments that measure young children’s strengths and competencies for the purpose of making decisions about teaching and learning, identifying areas of lesser strength, and for designing and evaluating interventions. The Preschool Behavioral and Emotional Rating Scale (PreBERS; Epstein & Synhorst, in press) is a standardized test designed to assess the emotional and behavioral strengths and competencies of children 3 to 5 years of age. Two studies investigated the PreBERS with parents as the primary respondents. The first study investigated the convergent validity of the PreBERS by comparing it to the Caregiver-Teacher Report Form (C-TRF; Achenbach & Rescorla, 2000). Because the PreBERS is a measure of emotional strengths and the C-TRF assesses problem behaviors, moderate to very large negative correlations (-.370 to -.775) were reported between the two measures. The second study investigated the test-retest reliability of the PreBERS over a one-month period. All of the correlations were over .787 indicating that the PreBERS is a stable measure across ratings. The results suggest that when parents are the primary respondents, the PreBERS is a valid and reliable measure for assessing emotional and behavioral strengths in preschool children

    Removal of violations of the Master Ward Identity in perturbative QFT

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    We study the appearance of anomalies of the Master Ward Identity, which is a universal renormalization condition in perturbative QFT. The main insight of the present paper is that any violation of the Master Ward Identity can be expressed as a LOCAL interacting field; this is a version of the well-known Quantum Action Principle of Lowenstein and Lam. Proceeding in a proper field formalism by induction on the order in â„Ź\hbar, this knowledge about the structure of possible anomalies as well as techniques of algebraic renormalization are used to remove possible anomalies by finite renormalizations. As an example the method is applied to prove the Ward identities of the O(N) scalar field model.Comment: 51 pages. v2: a few formulations improved, one reference added. v3: a few mistakes corrected and one additional reference. v4: version to be printed in Reviews in Mathematical Physic

    The Weekly Adjustment Indicators Checklist: An Application in the Child Welfare Field

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    Research on the effectiveness of various home-based interventions implemented in the 1980s and 1990s indicates that results have been equivocal. Because of the unique and complex behavioral challenges presented by each family and the need for individualized treatments and long-term interventions for these families, group research and evaluation designs are often insufficient in assessing effectiveness of home-based interventions. Alternative evaluation strategies are needed. The purpose of this exploratory study was two-fold: (a) to investigate the applicability and acceptability of the Weekly Adjustment Indicators Checklist (WAIC) in monitoring adult and child behaviors and (b) to monitor, on an on-going basis, the progress of a family referred to an urban family preservation and reunification program. The target family on whom data were collected consisted of a 13-year old girl and her foster parent who was her maternal aunt. The findings of this study indicate that the WAIC is applicable in monitoring the progress of children and adults in care and that it has the endorsement of its user, namely, the direct care provider. Other results of the study, limitations of the study, and future research needs are discussed

    Convergent Validity of the Strength-Based Behavioral and Emotional Rating Scale with Youth in a Residential Setting

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    Strength-based assessment has been identified as an appropriate approach to use in planning treatment and evaluating outcomes of youth in residential settings. In previous research the Behavioral and Emotional Rating Scale-2, a standardized and norm-referenced strength-based measure, has demonstrated adequate reliability and validity with youth served in community and educational settings. The purpose of the present study was to examine the internal reliability and convergent validity of the BERS-2 by comparing the test to the Child Behavior Checklist (CBCL) and the Symptoms and Functioning Severity Scale (SFSS). The results indicate that the scores from the BERS-2 are internally consistent and converge with other behavioral and emotional measures which, taken together, suggest that the BERS-2 could be acceptable for assessing the emotional and behavioral strengths of youth in residential settings. Study limitations and future research directions are identified

    Convergent Validity of the Strength-Based Behavioral and Emotional Rating Scale with Youth in a Residential Setting

    Get PDF
    Strength-based assessment has been identified as an appropriate approach to use in planning treatment and evaluating outcomes of youth in residential settings. In previous research the Behavioral and Emotional Rating Scale-2, a standardized and norm-referenced strength-based measure, has demonstrated adequate reliability and validity with youth served in community and educational settings. The purpose of the present study was to examine the internal reliability and convergent validity of the BERS-2 by comparing the test to the Child Behavior Checklist (CBCL) and the Symptoms and Functioning Severity Scale (SFSS). The results indicate that the scores from the BERS-2 are internally consistent and converge with other behavioral and emotional measures which, taken together, suggest that the BERS-2 could be acceptable for assessing the emotional and behavioral strengths of youth in residential settings. Study limitations and future research directions are identified
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