853 research outputs found

    Responses of Juvenile Atlantic Salmon to Competition and Environmental Change: Implications for Performance in Maine Streams

    Get PDF
    New England’s climate is changing faster than that of any other region in the continental United States. Over the last century, Maine has experienced an increase in annual temperature of approximately 1.48oC along with a 15 percent increase in annual precipitation. Temperature and precipitation play vital roles in shaping the ecology of freshwater environments. Therefore, changes in regional climate could undermine the structure and stability of Maine’s freshwater systems as they currently exist. Maine currently harbors the last wild populations of Atlantic salmon (Salmo salar) in the United States. Atlantic salmon were once abundant in Maine streams, but suffered dramatic declines due to several factors including deforestation, overfishing, and the construction of dams. In 2000, Atlantic salmon were listed as a Federally Endangered species. As juveniles, salmon spend 1 to 3 years in Maine streams before smolting. However, salmon face several threats as juveniles in Maine streams, including changes in climate as well as competition from introduced or invasive species which could outcompete salmon for resources. This dissertation examines these impacts on juvenile Atlantic salmon (Salmo salar) and the stream food webs in which they are embedded by (1.) Using temperature-controlled microcosm experiments to investigate the potential for climate-driven warming to exacerbate the effects of competition between native and invasive species from different thermal guilds. The results suggest that non-native smallmouth bass (Micropterus dolomeiu) have the potential to outcompete Atlantic salmon as waters continue to warm. (2.) Running dynamic regression models to analyze the relationship between juvenile Atlantic salmon condition, temperature, and precipitation for 9 streams across 4 drainages over a 16-year period. The results suggest that the impacts of climate change on salmon growth may vary by stream and spatial scale. (3.) Conducting an instream mesocosm experiment to investigate the food-web implications of interactions between omnivorous crayfish and predatory Atlantic Salmon. These results suggest that strong bottom-up processes occur when crayfish are present, whereby increased algal growth could promote the availability of macroinvertebrates important to salmon diet

    Energy and Security in the Industrializing World

    Get PDF
    Provides detailed analyses of the related concerns of energy needs, the economy, and national security for developing countries—Argentina, Brazil, Cuba, India, Pakistan, South Africa, South Korea, and Taiwan. The essays serve to underline the dangerous problem of nuclear proliferation for several of these countries have uneasy relations with their neighbors. In their detailed reviews of these eight nations—their plans and their capabilities—the contributors have provided a valuable source for a neglected area of international affairs. Raju G.C. Thomas is professor of Political Science at Marquette University.https://uknowledge.uky.edu/upk_energy_policy/1000/thumbnail.jp

    To be or not to be an auctioneer: Some thoughts on the legal nature of online eBay auctions and the protection of consumers

    Get PDF
    This paper discusses the legal classification of online “eBay” auctions. The discussion has key implications on the scope of consumer protection law as sale by auctions are, for example, excluded from the scope of the Consumer Protection (Distance Selling) Regulations 2000. The paper uncovers that online “eBay” auctions cannot always be considered as traditional auctions and that eBay, as an intermediary, is not to be considered as an auctioneer. This creates difficulties associated with a distributive application of consumer protection laws such as the Consumer Protection (Distance Selling) Regulations 2000. Another set of difficulties is associated with a lenient legal regime applicable to the liability of eBay under the Electronic Commerce (EC Directive) Regulations 2002 . The paper concludes that there is an urgent need to clarify the legal classification of online auctions and to rethink the liability of online auction sites to better protect consumers

    Kaon decay interferometry as meson dynamics probes

    Full text link
    We discuss the time dependent interferences between KLK_L and KSK_S in the decays in 3π3\pi and ππγ\pi\pi\gamma, to be studied at interferometry machines such as the ϕ\phi-factory and LEAR. We emphasize the possibilities and the advantages of using interferences, in comparison with width measurements, to obtain information both on CPCP conserving and CPCP violating amplitudes. Comparison with present data and suggestions for future experiments are made.Comment: 15 pages, in RevTex, Report INFNNA-IV-93-31, UTS-DFT-93-2

    Precision Timing with Silicon Sensors for Use in Calorimetry

    Get PDF
    The high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is expected to provide instantaneous luminosities of 5 × 10^(34) cm^(−2) s^(−1). The high luminosities expected at the HL-LHC will be accompanied by a factor of 5 to 10 more pileup compared with LHC conditions in 2015, causing general confusion for particle identification and event reconstruction. Precision timing allows to extend calorimetric measurements into such a high density environment by subtracting the energy deposits from pileup interactions. Calorimeters employing silicon as the active component have recently become a popular choice for the HL- LHC and future collider experiments which face very high radiation environments. We present studies of basic calorimetric and precision timing measurements using a prototype composed of tungsten absorber and silicon sensor as the active medium. We show that for the bulk of electromagnetic showers induced by electrons in the range of 20 GeV to 30 GeV, we can achieve time resolutions better than 25 ps per single pad sensor

    Test beam studies of silicon timing for use in calorimetry

    Get PDF
    The high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is expected to provide instantaneous luminosities of 5×10^(34) cm^(−2) s^(−1). The high luminosities expected at the HL-LHC will be accompanied by a factor of 5–10 more pileup compared with LHC conditions in 2015, further increasing the challenge for particle identification and event reconstruction. Precision timing allows us to extend calorimetric measurements into such a high density environment by subtracting the energy deposits from pileup interactions. Calorimeters employing silicon as the active component have recently become a viable choice for the HL-LHC and future collider experiments which face very high radiation environments. In this paper, we present studies of basic calorimetric and precision timing measurements using a prototype composed of tungsten absorber and silicon sensor as the active medium. We show that for the bulk of electromagnetic showers induced by electrons in the range of 20–30 GeV, we can achieve time resolutions better than 25 ps per single pad sensor

    Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

    Full text link
    Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors.Comment: Submitted for the January 2014 Fermilab Physics Advisory Committee meetin

    Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

    Get PDF
    Submitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingNeutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors

    Search for exchange-antisymmetric two-photon states

    Get PDF
    Atomic two-photon J=0 \leftrightarrowJ'=1 transitions are forbidden for photons of the same energy. This selection rule is related to the fact that photons obey Bose-Einstein statistics. We have searched for small violations of this selection rule by studying transitions in atomic Ba. We set a limit on the probability vv that photons are in exchange-antisymmetric states: v<1.2107v<1.2\cdot10^{-7}.Comment: 5 pages, 4 figures, ReVTeX and .eps. Submitted to Phys. Rev. Lett. Revised version 9/25/9
    corecore