972 research outputs found

    Modeling the Pseudodeductible in Insurance Claims Decisions

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    In many different managerial contexts, consumers “leave money on the table” by, for example, their failure to claim rebates, use available coupons, and so on. This project focuses on a related problem faced by homeowners who may be reluctant to file insurance claims despite the fact their losses are covered. We model this consumer decision by introducing the concept of the “pseudodeductible,” a latent threshold above the policy deductible that governs the homeowner’s claim behavior. In addition, we show how the observed number of claims can be modeled as the output of three stochastic processes that are separately, and in conjunction, managerially relevant: the rate at which losses occur, the size of each loss, and the choice of the individual to file or not file a claim. By allowing for the possibility of pseudodeductibles, one can sort out (and make accurate inferences about) these three processes. We test this model using a proprietary data set provided by State Farm, the largest underwriter of personal lines insurance in the United States. Using mixtures of Dirichlet processes to capture heterogeneity and the interplay among the three processes, we uncover several relevant “stories” that underlie the frequency and severity of claims. For instance, some customers have a small number of losses, but all are filed as claims, whereas others may experience many more losses, but are more selective about which claims they file. These stories explain several observed phenomena regarding the claims decisions that insurance customers make, and have broad implications for customer lifetime value and market segmentation

    Brief mindfulness training enhances cognitive control in socioemotional contexts: Behavioral and neural evidence.

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    In social contexts, the dynamic nature of others' emotions places unique demands on attention and emotion regulation. Mindfulness, characterized by heightened and receptive moment-to-moment attending, may be well-suited to meet these demands. In particular, mindfulness may support more effective cognitive control in social situations via efficient deployment of top-down attention. To test this, a randomized controlled study examined effects of mindfulness training (MT) on behavioral and neural (event-related potentials [ERPs]) responses during an emotional go/no-go task that tested cognitive control in the context of emotional facial expressions that tend to elicit approach or avoidance behavior. Participants (N = 66) were randomly assigned to four brief (20 min) MT sessions or to structurally equivalent book learning control sessions. Relative to the control group, MT led to improved discrimination of facial expressions, as indexed by d-prime, as well as more efficient cognitive control, as indexed by response time and accuracy, and particularly for those evidencing poorer discrimination and cognitive control at baseline. MT also produced better conflict monitoring of behavioral goal-prepotent response tendencies, as indexed by larger No-Go N200 ERP amplitudes, and particularly so for those with smaller No-Go amplitude at baseline. Overall, findings are consistent with MT's potential to enhance deployment of early top-down attention to better meet the unique cognitive and emotional demands of socioemotional contexts, particularly for those with greater opportunity for change. Findings also suggest that early top-down attention deployment could be a cognitive mechanism correspondent to the present-oriented attention commonly used to explain regulatory benefits of mindfulness more broadly

    Comprehensive characterization of molecular interactions based on nanomechanics

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    Molecular interaction is a key concept in our understanding of the biological mechanisms of life. Two physical properties change when one molecular partner binds to another. Firstly, the masses combine and secondly, the structure of at least one binding partner is altered, mechanically transducing the binding into subsequent biological reactions. Here we present a nanomechanical micro-array technique for bio-medical research, which not only monitors the binding of effector molecules to their target but also the subsequent effect on a biological system in vitro. This label-free and real-time method directly and simultaneously tracks mass and nanomechanical changes at the sensor interface using micro-cantilever technology. To prove the concept we measured lipid vesicle (approximately 748*10(6) Da) adsorption on the sensor interface followed by subsequent binding of the bee venom peptide melittin (2840 Da) to the vesicles. The results show the high dynamic range of the instrument and that measuring the mass and structural changes simultaneously allow a comprehensive discussion of molecular interactions

    Energy and Charged Particle Flow in 10.8 A GeV/c Au+Au Collisions

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    Experimental results and a detailed analysis are presented of the transverse energy and charged particle azimuthal distributions measured by the E877 collaboration for different centralities of Au+Au collisions at a beam momentum of 10.8 A GeV/c. The anisotropy of these distributions is studied with respect to the reaction plane reconstructed on an event-by-event basis using the transverse energy distribution measured by calorimeters. Results are corrected for the reaction plane resolution. For semicentral events we observe directed flow signals of up to ten percent. We observe a stronger anisotropy for slow charged particles. For both the charged particle and transverse energy distributions we observe a small but non zero elliptic anisotropy with the major axis pointing into the reaction plane. Combining the information on transverse energy and charged particle flow we obtain information on the flow of nucleons and pions. The data are compared to event generators and the need to introduce a mean field or nucleon-nucleon potential is discussed.Comment: RevTex, 25 pages, 13 figures included as one Postscript file, submitted to Phys. Rev.

    A Phase I/IIA Clinical Study With A Chimeric Mouse-Human Monoclonal Antibody To The V3 Loop Of Human Immunodeficiency Virus Type 1 Gp120

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    A phase I/IIA clinical trial with the chimeric mouse-human monoclonal antibody CGP 47 439 to the principal neutralization determinant in the V3 region of human immunodeficiency virus type 1 (HIV-1) strain IIIB envelope protein gp 120 is reported. The trial was an uncontrolled single-center, open-label, multidose tolerability, immunogenicity, and pharmacokinetic study in homosexual men with advanced HIV disease. Patient groups were formed on the basis of the reactivity of the antibody with the gp 120 of their HIV-1 isolates. Intravenous infusions of 1, 10, and 25 mg of antibody were followed by seven escalated doses of 50, 100, and 200 mg, every 3 weeks. The antibody was well tolerated; no toxicity was observed. Some patients showed a transient but insignificant antibody response to the antibody with no apparent adverse reactions or accelerated elimination of it. Substantial serum levels of the antibody were maintained with a mean t1/2β of 8-16 days. A virus burden reduction was observed in some patient

    Electromagnetic transitions of the helium atom in superstrong magnetic fields

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    We investigate the electromagnetic transition probabilities for the helium atom embedded in a superstrong magnetic field taking into account the finite nuclear mass. We address the regime \gamma=100-10000 a.u. studying several excited states for each symmetry, i.e. for the magnetic quantum numbers 0,-1,-2,-3, positive and negative z parity and singlet and triplet symmetry. The oscillator strengths as a function of the magnetic field, and in particular the influence of the finite nuclear mass on the oscillator strengths are shown and analyzed.Comment: 10 pages, 8 figure

    Establishment of proteome reference maps for somatic and zygotic embryos of Cyclamen persicum mill.

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    Comprehensive proteomic characterizations were performed aiming to create proteome reference maps for somatic and zygotic embryos of Cyclamen persicum. Separation by two dimensional isoelectric focusing - sodium dodecyl sulfate polyacrylamide gel electrophoresis led to a resolution of more than 800 protein spots for each tissue. Approximately 70% of the spots likewise appeared in both zygotic and in somatic embryo's protein fractions. However, differential gel electrophoresis analyses revealed pronounced differences in abundances for the majority of proteins present in both tissues. MS analyses for 300 reproducible spots in total (263 of the zygotic embryos' protein fraction and 37 spots appearing specifically in the somatic embryos' proteome) led to identification of 261 proteins, 35 of which were specific or highly abundant in gels of the somatic embryo's tissue. Most identified proteins were found to be involved in glycolysis or gluconeogenesis and stress response pathways

    Towards a better understanding of somatic embryogenesis in Cyclamen persicum

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    Somatic embryogenesis in Cyclamen persicum was first reported in 1984 and has potential applications for propagation and breeding of this economically important ornamental crop. This in vitro regeneration system can be used for vegetative propagation of parental lines of F1 hybrids and elite plants, production of artificial seeds, Agrobacterium tumefaciens-mediated genetic transformation, long-term cryopreservation, protoplast to plant regeneration and somatic hybridization. Somatic embryogenesis was shown to be a powerful propagation system for some C. persicum genotypes, but commercial application in large scale so far is hindered by several limitations, i.e., asynchronous development, malformations or secondary somatic embryogenesis. However, recent molecular approaches by transcriptomic and proteomic analyses were undertaken in order to better understand and control this in vitro regeneration system and to overcome these problems. Our studies aim at comparing somatic embryos to their zygotic counterparts regarding their proteomes. Protein separation by two dimensional isoelectric focusing - sodium do-decyl sulfate polyacrylamide gel electrophoresis led to a resolution of about 1000 protein spots per gel, of which the first 253 were identified by mass spectrometry. Most were found to be involved in glycolysis/gluconeogenesis and stress response pathways. A proteome reference map of zygotic embryos will be publicly released soon and may serve as a basis for further investigations and improvements of somatic embryogenesis

    Transverse flow and hadro-chemistry in Au+Au collisions at \sqrt{s_{NN}}=200 GeV

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    We present a hydrodynamic assessment of preliminary particle spectra observed in Au+Au collisions at \sqrt{s_{NN}}=200 GeV. The hadronic part of the underlying equation of state is based on explicit conservation of (measured) particle ratios throughout the resonance gas stage after chemical freezeout by employing chemical potentials for stable mesons, nucleons and anti-nucleons. We find that under these conditions the data (in particular the proton spectra) favor a low freeze-out temperature of around 100 MeV. Furthermore we show that through inclusion of a moderate pre-hydrodynamic transverse flow field the shape of the spectra improves with respect to the data. The effect of the initial transverse boost on elliptic flow and the freeze-out geometry of the system is also elucidated.Comment: as published: more data included in Fig. 1, discussions throughout the text improved, 6 pages, 4 figure

    Gauge dependence and matching procedure of a nonrelativistic QED/QCD boundstate formalism

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    A nonrelativistic boundstate formalism used in contemporary calculations is investigated. It is known that the effective Hamiltonian of the boundstate system depends on the choice of gauge. We obtain the transformation charge Q of the Hamiltonian for an arbitrary infinitesimal change of gauge, by which gauge independence of the mass spectrum and gauge dependences of the boundstate wave functions are dictated. We give formal arguments based on the BRST symmetry supplemented by power countings of Coulomb singularities of diagrams. For illustration: (1)we calculate Q up to O(1/c), (2)we examine gauge dependences of diagrams for a decay of a qqbar boundstate up to O(1/c) and show that cumbersome gauge cancellations can be circumvented by directly calculating Q. As an application we point out that the present calculations of top quark momentum distribution in the ttbar threshold region are gauge dependent. We also show possibilities for incorrect calculations of physical quantities of boundstates when the on-shell matching procedure is employed. We give a proof of a justification for the use of the equation of motion to simplify the form of a local NRQCD Lagrangian. The formalism developed in this work will provide useful cross checks in computations involving NRQED/NRQCD boundstates.Comment: 30 pages, 15 figures (ver1); Presentations of Introduction and Conclusion were modified substantially, although none of our findings have been changed; Side remarks have been added in various parts of the paper. (ver2); Supplementary remarks and minor corrections (ver3
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