717 research outputs found

    Social-Ecological Change, Resilience, and Adaptive Capacity in the McKenzie River Valley, Oregon

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    This study explores perceptions of long-term residents regarding links between governance, landscape, and community change in the McKenzie River Valley (MRV) in western Oregon and provides a general assessment of factors affecting resilience and adaptive capacity. Residents interviewed indicated that dramatic changes driven by market competition, timber industry changes, increased regulation, and rural restructuring have occurred in both the landscape and community. The changes that have transpired have redefined the relationship between the community and the landscape, moving away from local dependence on timber harvests to an economy focused on tourism and other ecosystem services. In doing so the community has transitioned from one with a logging community identity to one that has begrudgingly become a retirement and vacation community. We found that the social-ecological system (SES) in the MRV is still in the midst of reorganization in the wake of the 1990s Timber Wars. As a result of low institutional capacity, the system is vulnerable to exogenous drivers of change. Using a modified version of Ostrom’s (2009) framework for SES analysis, this study recommends policymakers and policy entrepreneurs take three key steps to facilitate enhanced resilience and adaptive capacity: 1) support transboundary management strategies that transcend landownership classifications; 2) tighten system feedbacks to include more local influence; and 3) develop local multilayered institutions organized vertically and horizontally. Future research should explore the potential for collaborative forestry and stewardship contracting to enhance social-ecological resilience in this valley

    Comment on "Hara's theorem in the constituent quark model"

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    It is pointed out that current conservation alone does not suffice to prove Hara's theorem as it was claimed recently. By explicit calculation we show that the additional implicit assumption made in such "proofs" is that of a sufficiently localized current.Comment: 8 pages, Late

    Nucleosynthesis imprints from different Type Ia Supernova explosion scenarios and implications for galactic chemical evolution

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    We analyze the nucleosynthesis yields of various Type Ia supernova explosion simulations including pure detonations in sub- Chandrasekhar mass white dwarfs, double detonations and pure helium detonations of sub-Chandrasekhar mass white dwarfs with an accreted helium envelope, a violent merger model of two white dwarfs and deflagrations as well as delayed detonations in Chandrasekhar mass white dwarfs. We focus on the iron peak elements Mn, Zn and Cu. To this end, we also briefly review the different burning regimes and production sites of these elements as well as the results of abundance measurements and several galactic chemical evolution studies. We find that super-solar values of [Mn/Fe] are not restricted to Chandrasekhar mass explosion models. Scenarios including a helium detonation can significantly contribute to the production of Mn, in particular the models proposed for calcium-rich transients. Although Type Ia supernovae are often not accounted for as production sites of Zn and Cu, our models involving helium shell detonations can produce these elements in super-solar ratios relative to Fe. Our results suggest a re-consideration of Type Ia supernova yields in galactic chemical evolution models. A detailed comparison with observations can provide new insight into the progenitor and explosion channels of these events.Comment: 15 paged, 8 figures, accepted for publication in A&

    GDR Feeding of the Highly-Deformed Band in 42Ca

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    The gamma-ray spectra from the decay of the GDR in the compound nucleus reaction 18O+28Si at bombarding energy of 105 MeV have been measured in an experiment using the EUROBALL IV and HECTOR arrays. The obtained experimental GDR strength function is highly fragmented, with a low energy (10 MeV) component, indicating a presence of a large deformation and Coriolis effects. In addition, the preferential feeding of the highly-deformed band in 42Ca by this GDR low energy component is observed.Comment: 6 pages, 2 figures, Proceedings of the Zakopane2004 Symposium, to be published in Acta Phys. Pol. B36 (2005

    Resonances in radiative hyperon decays

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    The importance of resonances for the radiative hyperon decays is examined in the framework of chiral perturbation theory. Low lying baryon resonances are included into the effective theory and tree contributions to these decays are calculated. We find significant contributions to both the parity-conserving and parity-violating decay amplitudes and a large negative value for the asymmetry parameter in polarized Sigma^+ -> p gamma is found, in agreement with the experimental result alpha(p Sigma^+) = -0.76 +/- 0.08.Comment: 14 pages, 2 figure

    Ammonium tetrathiomolybdate following ischemia/reperfusion injury: Chemistry, pharmacology, and impact of a new class of sulfide donor in preclinical injury models

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    Background: Early revascularization of ischemic organs is key to improving outcomes, yet consequent reperfusion injury may be harmful. Reperfusion injury is largely attributed to excess mitochondrial production of reactive oxygen species (ROS). Sulfide inhibits mitochondria and reduces ROS production. Ammonium tetrathiomolybdate (ATTM), a copper chelator, releases sulfide in a controlled and novel manner, and may offer potential therapeutic utility. Methods and findings: In vitro, ATTM releases sulfide in a time-, pH-, temperature-, and thiol-dependent manner. Controlled sulfide release from ATTM reduces metabolism (measured as oxygen consumption) both in vivo in awake rats and ex vivo in skeletal muscle tissue, with a superior safety profile compared to standard sulfide generators. Given intravenously at reperfusion/resuscitation to rats, ATTM significantly reduced infarct size following either myocardial or cerebral ischemia, and conferred survival benefit following severe hemorrhage. Mechanistic studies (in vitro anoxia/reoxygenation) demonstrated a mitochondrial site of action (decreased MitoSOX fluorescence), where the majority of damaging ROS is produced. Conclusions: The inorganic thiometallate ATTM represents a new class of sulfide-releasing drugs. Our findings provide impetus for further investigation of this compound as a novel adjunct therapy for reperfusion injury

    A QCD Sum Rule Approach to the s→dγs\to d\gamma Contribution to the Ω−→Ξ−γ\Omega^-\to \Xi^-\gamma Radiative Decay

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    QCD sum rules are used to calculate the contribution of short-distance single-quark transition s→dγs\rightarrow d \gamma, to the amplitudes of the hyperon radiative decay, Ω−→Ξ−γ\Omega^-\rightarrow \Xi^-\gamma. We re-evaluate the Wilson coefficient of the effective operator responsible for this transition. We obtain a branching ratio which is comparable to the unitarity limit.Comment: 15 pages, Revtex, 13 figures available as a uuencoded, gz-compressed ps fil
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