2,994 research outputs found

    Regulating altruistic agents

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    Altruism or `regard for others' can encourage self-restraint among generators of negative externalities, thereby mitigating the externality problem. We explore how introducing impure altruism into standard regulatory settings alters regulatory prescriptions. We show that the optimal calibration of both quantitative controls and externality taxes are affected. It also leads to surprising results on the comparative performance of instruments. Under quantity-based regulation welfare is increasing in the propensity for altruism in the population; under price-based regulation the relationship is non-monotonic. Price-based regulation is preferred when the population is either predominantly altruistic or predominantly selfish, quantity-based regulation for cases in between

    Enterovirus Plaque Technique : Utilization of Maintenance Medium on Agar Overlay without Neutral Red

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    Author Institution: The Defiance College, Defiance, OhioA plaque technique for quantitating enteric viruses using liquid growth medium on the agar overlay was developed. Deletion of neutral red and staining of plaques using crystal violet, following plaque development, facilitated the technique. This method utilized a minimal number of monkey kidney epithelial cells for testing the greatest number of samples

    High Power Microwave Operational Exposure Detection using Thermoacoustic Wave Generation in Lossy Dielectric Polymers

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    A feasibility analysis for the use of microwave-induced thermoacoustic (TA) wave generation in lossy dielectric media to detect pulsed high power microwave directed energy weapons in force health protection applications was conducted based on a series of empirical and computational investigations. A potential target volume material, carbon-loaded polytetrafluoroethylene, was identified for further study based on anticipated complex dielectric properties, with laboratory measurements of select electromagnetic (EM), thermal, and elastic material properties of relevance to the TA effect conducted to determine parameter values. A planar geometry TA-based signal chain model using thin film piezoelectric sensors was developed for both finite element method based numerical simulation and in-beam response testing, with TA signal output evaluated in the time and frequency domain using both approaches. Based on empirically-derived complex permittivity values, a single-term Cole-Cole dielectric relaxation model approximation was developed over the 2-110 GHz microwave frequency region to permit a more general evaluation of EM coupling efficiency of the material. Modeling and simulation of the idealized signal chain allowed the analysis of TA waveform dependency on microwave beam parameters not otherwise accessible during in-beam response testing. High frequency TA signal data was suitably fit to a pulse width sensitivity impulse response function model for the target geometry and found to be in good agreement for personnel exposure applications

    Nonabelian dark matter: models and constraints

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    Numerous experimental anomalies hint at the existence of a dark matter (DM) multiplet chi_i with small mass splittings. We survey the simplest such models which arise from DM in the low representations of a new SU(2) gauge symmetry, whose gauge bosons have a small mass mu < 1 GeV. We identify preferred parameters M_chi ~ 1 TeV, mu ~ 100 MeV, alpha_g ~ 0.04 and the chi chi -> 4e annihilation channel, for explaining PAMELA, Fermi, and INTEGRAL/SPI lepton excesses, while remaining consistent with constraints from relic density, diffuse gamma rays and the CMB. This consistency is strengthened if DM annihilations occur mainly in subhalos, while excitations (relevant to the excited DM proposal to explain the 511 keV excess) occur in the galactic center (GC), due to higher velocity dispersions in the GC, induced by baryons. We derive new constraints and predictions which are generic to these models. Notably, decays of excited DM states chi' -> chi gamma arise at one loop and could provide a new signal for INTEGRAL/SPI; big bang nucleosynthesis (BBN) constraints on the density of dark SU(2) gauge bosons imply a lower bound on the mixing parameter epsilon between the SU(2) gauge bosons and photon. These considerations rule out the possibility of the gauge bosons that decay into e^+e^- being long-lived. We study in detail models of doublet, triplet and quintuplet DM, showing that both normal and inverted mass hierarchies can occur, with mass splittings that can be parametrically smaller, e.g., O(100) keV, than the generic MeV scale of splittings. A systematic treatment of Z_2 symmetry which insures the stability of the intermediate DM state is given for cases with inverted mass hierarchy, of interest for boosting the 511 keV signal from the excited dark matter mechanism.Comment: 28 pages, 17 figures; v2. added brief comment, reference

    Exploring a search for long-duration transient gravitational waves associated with magnetar bursts

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    Soft gamma repeaters and anomalous X-ray pulsars are thought to be magnetars, neutron stars with strong magnetic fields of order 1013\mathord{\sim} 10^{13}--1015gauss10^{15} \, \mathrm{gauss}. These objects emit intermittent bursts of hard X-rays and soft gamma rays. Quasiperiodic oscillations in the X-ray tails of giant flares imply the existence of neutron star oscillation modes which could emit gravitational waves powered by the magnetar's magnetic energy reservoir. We describe a method to search for transient gravitational-wave signals associated with magnetar bursts with durations of 10s to 1000s of seconds. The sensitivity of this method is estimated by adding simulated waveforms to data from the sixth science run of Laser Interferometer Gravitational-wave Observatory (LIGO). We find a search sensitivity in terms of the root sum square strain amplitude of hrss=1.3×1021Hz1/2h_{\mathrm{rss}} = 1.3 \times 10^{-21} \, \mathrm{Hz}^{-1/2} for a half sine-Gaussian waveform with a central frequency f0=150Hzf_0 = 150 \, \mathrm{Hz} and a characteristic time τ=400s\tau = 400 \, \mathrm{s}. This corresponds to a gravitational wave energy of EGW=4.3×1046ergE_{\mathrm{GW}} = 4.3 \times 10^{46} \, \mathrm{erg}, the same order of magnitude as the 2004 giant flare which had an estimated electromagnetic energy of EEM=1.7×1046(d/8.7kpc)2ergE_{\mathrm{EM}} = \mathord{\sim} 1.7 \times 10^{46} (d/ 8.7 \, \mathrm{kpc})^2 \, \mathrm{erg}, where dd is the distance to SGR 1806-20. We present an extrapolation of these results to Advanced LIGO, estimating a sensitivity to a gravitational wave energy of EGW=3.2×1043ergE_{\mathrm{GW}} = 3.2 \times 10^{43} \, \mathrm{erg} for a magnetar at a distance of 1.6kpc1.6 \, \mathrm{kpc}. These results suggest this search method can probe significantly below the energy budgets for magnetar burst emission mechanisms such as crust cracking and hydrodynamic deformation
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