17,009 research outputs found

    Experiences in wetland co-management: the MACH project

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    Wetlands, Fishery management

    A Mass Formula from Light to Hypernuclei

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    Simultaneous description of ordinary and hypernuclei masses by a single mass formula has been a great challenge in nuclear physics. Hyperon-separation energies of about forty Lambda(Λ\Lambda), three Lambda-Lambda(ΛΛ\Lambda\Lambda), one Sigma(Σ\Sigma) and seven Cascade(Ξ\Xi) hypernuclei have been experimentally found. Many of these nuclei are of light masses. We prescribe a new mass formula, called BWMH, which describes the normal and hypernuclei on the same footing. It is based on the modified-Bethe-Weizs\"acker mass formula (BWM). BWM is basically an extension of the Bethe-Weizs\"acker mass formula (BW) for light nuclei. The parameters of BWM were optimized by fitting about 3000 normal nuclei available recently. The original Bethe-Weizs\"acker mass formula (BW) was designed for medium and heavy mass nuclei and it fails for light nuclei. Two earlier works on hypernuclei based on this BW show some limitations. The BWMH gives improved agreement with the experimental data for the line of stability, one-neutron separation energy versus neutron number spectra of normal nuclei, and the hyperon-separation energies from hypernuclei. The drip lines are modified for addition of a Λ\Lambda hyperon in a normal nucleus.Comment: Presented at the "XXIX Mazurian Lakes Conference on Physics: Nuclear Physics and the Fundamental Processes, Piaski, Poland, August 30 - September 6, 2005." (7 pages, 1 Table, 1 Figure

    Deterrence, preemption and panic: A Common-enemy problem of terrorism

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    We develop a game-theoretic analysis of terrorism that examines the interaction between a terrorist organization and multiple target countries, and considers both pre-emption and deterrence as counterterrorist policies. The damage from terror includes not only the material cost of fatality, injury and loss of property, but also the resultant fear. The fear-effect leads to different kinds of equilibria and implications for counter-terrorism policies. In particular, the model identifies conditions under which greater pre-emption may be the rational response to an increase in terrorism, i.e., it analyzes the merit of the dictum: "offense is the best defense." Further, it examines the characteristics of cooperative behavior among target countries in dealing with the threat of terrorism.Terrorism; Preemption; Panic; Deterrence; Cooperation; Target Countries
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