255 research outputs found

    Theory of agent-based market models with controlled levels of greed and anxiety

    Full text link
    We use generating functional analysis to study minority-game type market models with generalized strategy valuation updates that control the psychology of agents' actions. The agents' choice between trend following and contrarian trading, and their vigor in each, depends on the overall state of the market. Even in `fake history' models, the theory now involves an effective overall bid process (coupled to the effective agent process) which can exhibit profound remanence effects and new phase transitions. For some models the bid process can be solved directly, others require Maxwell-construction type approximations.Comment: 30 pages, 10 figure

    Neutron time-of-flight measurements of charged-particle energy loss in inertial confinement fusion plasmas

    Get PDF
    Neutron spectra from secondary ^{3}H(d,n)α reactions produced by an implosion of a deuterium-gas capsule at the National Ignition Facility have been measured with order-of-magnitude improvements in statistics and resolution over past experiments. These new data and their sensitivity to the energy loss of fast tritons emitted from thermal ^{2}H(d,p)^{3}H reactions enable the first statistically significant investigation of charged-particle stopping via the emitted neutron spectrum. Radiation-hydrodynamic simulations, constrained to match a number of observables from the implosion, were used to predict the neutron spectra while employing two different energy loss models. This analysis represents the first test of stopping models under inertial confinement fusion conditions, covering plasma temperatures of k_{B}T≈1-4  keV and particle densities of n≈(12-2)×10^{24}  cm^{-3}. Under these conditions, we find significant deviations of our data from a theory employing classical collisions whereas the theory including quantum diffraction agrees with our data

    Slowly evolving random graphs II: Adaptive geometry in finite-connectivity Hopfield models

    Full text link
    We present an analytically solvable random graph model in which the connections between the nodes can evolve in time, adiabatically slowly compared to the dynamics of the nodes. We apply the formalism to finite connectivity attractor neural network (Hopfield) models and we show that due to the minimisation of the frustration effects the retrieval region of the phase diagram can be significantly enlarged. Moreover, the fraction of misaligned spins is reduced by this effect, and is smaller than in the infinite connectivity regime. The main cause of this difference is found to be the non-zero fraction of sites with vanishing local field when the connectivity is finite.Comment: 17 pages, 8 figure

    Toward a Deeper Understanding of the Meaning of Marriage Among Black Men

    Get PDF
    Black men benefit from healthy, satisfying marriages in domains of physical, psychological, and financial well-being. Yet marriage among Black men has declined and remains elusive for many. One gap in the research concerns the positive meaning that Black men find in their marriages. Prior research has failed to collect in-depth accounts of Black men’s experiences of marriage. The purpose of this qualitative study is to explore the meaning of marriage among 52 Black men, using interview data. Findings highlight four themes in the meaning of marriage—secure emotional support, lifelong commitment, enhanced life success, and secure attachment. Two themes emerged from the data related to important influences on the construction of meaning relative to marriage—faith, and the dynamics of give and take. Responses among the men concerning the change in marriage over time related to transitions in American marriages and a deepened respect for marriage. Implications are discussed

    Registration of ‘NH03614 CL’ Wheat

    Get PDF
    ‘NH03614 CL’ (Reg. No. CV-1051, PI 653833) hard red winter wheat (Triticum aestivum L.) was developed cooperatively by the Nebraska Agricultural Experiment Station and the USDA-ARS and released in 2008 by the developing institutions and the South Dakota Agricultural Experiment Station and the Wyoming Agricultural Experiment Station. In addition to researchers at the releasing institutions, USDA-ARS researchers at Manhattan, KS and St. Paul, MN participated in the development of NH03614 CL. NH03614 CL was selected from the cross ‘Wesley’ sib//‘Millennium’ sib/‘Above’ sib that was made in the spring of 1997 to develop new herbicide-tolerant cultivars. NH03614 CL was selected using the bulk breeding method as an F3:4 line (F3–derived line in the F4 generation) in 2001, and in 2003 was assigned experimental line number NH03164. NH03614 CL was released primarily for its herbicide tolerance to imadazolinone compounds which control many previously diffi cult-to-control weeds in wheat production systems, and for its superior adaptation to rainfed wheat production systems in Nebraska, Wyoming, South Dakota, and counties in adjacent states

    T–T Neutron Spectrum from Inertial Confinement Implosions

    Get PDF
    A new technique that uses inertial confinement implosions for measuring low-energy nuclear reactions important to nuclear astrophysics is described. Simultaneous measurements of n–D and n–T elastic scattering at 14.1 MeV using deuterium–tritium gas-filled capsules provide a proof of principle for this technique. Measurements have been made of D(d,p)T (dd) and T(t,2n)[superscript 4]He (tt) reaction yields relative to the D(t,n)[superscript]He (dt) reaction yield for deuterium–tritium mixtures with fT/fD between 0.62 and 0.75 and for a wide range of ion temperatures to test our understanding of the implosion processes. Measurements of the shape of the neutron spectrum from the T(t,2n)[superscript 4]He reaction have been made for each of these target configurations.National Laser User’s Facility (Grant NA0000877)United States. Dept. of Energy (Grant DE-FG52-09NA29553)University of Rochester. Fusion Science Center (Rochester Subaward 415023-G, UR Account 5-24431)University of Rochester. Laboratory for Laser Energetics (Grant 412160-001G)Lawrence Livermore National Laboratory (Grants B580243 and DE-AC52-07NA27344

    Towards a characterization of behavior-disease models

    Get PDF
    The last decade saw the advent of increasingly realistic epidemic models that leverage on the availability of highly detailed census and human mobility data. Data-driven models aim at a granularity down to the level of households or single individuals. However, relatively little systematic work has been done to provide coupled behavior-disease models able to close the feedback loop between behavioral changes triggered in the population by an individual's perception of the disease spread and the actual disease spread itself. While models lacking this coupling can be extremely successful in mild epidemics, they obviously will be of limited use in situations where social disruption or behavioral alterations are induced in the population by knowledge of the disease. Here we propose a characterization of a set of prototypical mechanisms for self-initiated social distancing induced by local and non-local prevalence-based information available to individuals in the population. We characterize the effects of these mechanisms in the framework of a compartmental scheme that enlarges the basic SIR model by considering separate behavioral classes within the population. The transition of individuals in/out of behavioral classes is coupled with the spreading of the disease and provides a rich phase space with multiple epidemic peaks and tipping points. The class of models presented here can be used in the case of data-driven computational approaches to analyze scenarios of social adaptation and behavioral change.Comment: 24 pages, 15 figure
    • …
    corecore