138 research outputs found
Decision Costs and Welfare Effects of Democratic Voting Rules: An Experimental Analysis
What impact do majority rule and unanimity rule have on welfare and decision costs? According to Buchanan and Tullock ([1962] 1999) the unanimity principle must be regarded as a democratic norm, because it guarantees Pareto-efficient welfare effects. We present experimental results from a public goods game, which demonstrate in contrast to this assumption that majority rule can produce greater welfare effects than unanimity rule. This result suggests a critical revision of theoretical approaches which narrow the legitiÂmacy of majority rule in this respect
Structure and stability of non-symmetric Burgers vortices
We investigate, numerically and analytically, the structure and stability of steady and quasi-steady solutions of the Navier–Stokes equations corresponding to stretched vortices embedded in a uniform non-symmetric straining field, ([alpha]x, [beta]y, [gamma]z), [alpha]+[beta]+[gamma]=0, one principal axis of extensional strain of which is aligned with the vorticity. These are known as non-symmetric Burgers vortices (Robinson & Saffman 1984). We consider vortex Reynolds numbers R=[Gamma]/(2[pi]v) where [Gamma] is the vortex circulation and v the kinematic viscosity, in the range R=1[minus sign]104, and a broad range of strain ratios [lambda]=([beta][minus sign][alpha])/([beta]+[alpha]) including [lambda]>1, and in some cases [lambda][dbl greater-than sign]1. A pseudo-spectral method is used to obtain numerical solutions corresponding to steady and quasi-steady vortex states over our whole (R, [lambda]) parameter space including [lambda] where arguments proposed by Moffatt, Kida & Ohkitani (1994) demonstrate the non-existence of strictly steady solutions. When [lambda][dbl greater-than sign]1, R[dbl greater-than sign]1 and [epsilon][identical with][lambda]/R[double less-than sign]1, we find an accurate asymptotic form for the vorticity in a region 11. An iterative technique based on the power method is used to estimate the largest eigenvalues for the non-symmetric case [lambda]>0. Stability is found for 0[less-than-or-eq, slant][lambda][less-than-or-eq, slant]1, and a neutrally convective mode of instability is found and analysed for [lambda]>1. Our general conclusion is that the generalized non-symmetric Burgers vortex is unconditionally stable to two-dimensional disturbances for all R, 0[less-than-or-eq, slant][lambda][less-than-or-eq, slant]1, and that when [lambda]>1, the vortex will decay only through exponentially slow leakage of vorticity, indicating extreme robustness in this case
Decision Costs and Welfare Effects of Democratic Voting Rules: An Experimental Analysis
What impact do majority rule and unanimity rule create on welfare and decision costs? According to Buchanan and Tullock ([1962] 1999) the unanimity principle must be regarded as a democratic norm, because it guarantees Pareto-efficient welfare effects. We present experimental results from a public goods game, which demonstrate in contrast to this assumption that majority rule can produce larger welfare effects than unanimity rule. This result suggests a critical revision of theoretical approaches which narrow the legitimacy of majority rule in this respect
Electromagnetic Couplings of Nucleon Resonances
An effective Lagrangian calculation of pion photoproduction including all
nucleon resonances up to GeV is presented. We compare our
results to recent calculations and show the influence of different width
parametrizations and offshell cutoffs on the photoproduction multipoles. We
determine the electromagnetic couplings of the resonances from a new fit to the
multipole data.Comment: 20 pages, latex, 6 figures. Misprints corrected, text & 3 figures
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eta-photoproduction in the resonance energy region
The production in the nucleon resonance energy region is studied
within the unitary coupled-channels effective Lagrangian approach of the
Giessen model. We demonstrate that the second peak recently observed in the
cross section of photoproduction on the neutron at =1.66 GeV
can be explained in terms of coupled-channel effects due to and
resonance excitations
Pure Stationary States of Open Quantum Systems
Using Liouville space and superoperator formalism we consider pure stationary
states of open and dissipative quantum systems. We discuss stationary states of
open quantum systems, which coincide with stationary states of closed quantum
systems. Open quantum systems with pure stationary states of linear oscillator
are suggested. We consider stationary states for the Lindblad equation. We
discuss bifurcations of pure stationary states for open quantum systems which
are quantum analogs of classical dynamical bifurcations.Comment: 7p., REVTeX
Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV I: pion-induced results and hadronic parameters
We present a nucleon resonance analysis by simultaneously considering all
pion- and photon-induced experimental data on the final states gamma N, pi N, 2
pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass
up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the
resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The
omega N production mechanism is dominated by large P_{11}(1710) and
P_{13}(1900) contributions. In this first part, we present the results of the
pion-induced reactions and the extracted resonance and background properties
with emphasis on the difference between global and purely hadronic fits.Comment: 54 pages, 26 figures, discussion extended, typos corrected,
references updated, to appear in Phys. Rev.
Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV II: photon-induced results
We present a nucleon resonance analysis by simultaneously considering all
pion- and photon-induced experimental data on the final states gamma N, pi N, 2
pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass
up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the
resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The
omega N production mechanism is dominated by large P_{11}(1710) and
P_{13}(1900) contributions. In this second part we present the results on the
photoproduction reactions and the electromagnetic properties of the resonances.
The inclusion of all important final states up to sqrt(s) = 2 GeV allows for
estimates on the importance of the individual states for the GDH sum rule.Comment: 41 pages, 26 figures, discussion extended, typos corrected,
references updated, to appear in Phys. Rev.
A unitary model for meson-nucleon scattering
In an effective Lagrangian model employing the K-matrix approximation we
extract nucleon resonance parameters. To this end we analyze simultaneously all
available data for reactions involving the final states , ,
and in the energy range GeV. The background contributions are generated consistently from the
relevant Feynman amplitudes, thus significantly reducing the number of free
parameters.Comment: Revised version. 60 pages, 17 figures. Two figures and a short
discussion (\pi N \to \eta N, K \Lambda amplitudes) added, typos and minor
errors in the citations correcte
Therapeutic DNA vaccine induces broad T cell responses in the gut and sustained protection from viral rebound and AIDS in SIV-infected rhesus macaques.
Immunotherapies that induce durable immune control of chronic HIV infection may eliminate the need for life-long dependence on drugs. We investigated a DNA vaccine formulated with a novel genetic adjuvant that stimulates immune responses in the blood and gut for the ability to improve therapy in rhesus macaques chronically infected with SIV. Using the SIV-macaque model for AIDS, we show that epidermal co-delivery of plasmids expressing SIV Gag, RT, Nef and Env, and the mucosal adjuvant, heat-labile E. coli enterotoxin (LT), during antiretroviral therapy (ART) induced a substantial 2-4-log fold reduction in mean virus burden in both the gut and blood when compared to unvaccinated controls and provided durable protection from viral rebound and disease progression after the drug was discontinued. This effect was associated with significant increases in IFN-γ T cell responses in both the blood and gut and SIV-specific CD8+ T cells with dual TNF-α and cytolytic effector functions in the blood. Importantly, a broader specificity in the T cell response seen in the gut, but not the blood, significantly correlated with a reduction in virus production in mucosal tissues and a lower virus burden in plasma. We conclude that immunizing with vaccines that induce immune responses in mucosal gut tissue could reduce residual viral reservoirs during drug therapy and improve long-term treatment of HIV infection in humans
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