217 research outputs found

    LCLS LLRF UPGRADES TO THE SLAC LINAC*

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    The Linac Coherent Light Source (LCLS) at SLAC will be the brightest X-ray laser in the world when it comes on line. In order to achieve the brightness a 200fS length electron bunch is passed through an undulator. To create the 200fS, 3kA bunch, a 10pS electron bunch, created from a photo cathode in an RF gun, is run off crest on the RF to set up a position to energy correlation. The bunch is then compressed by chicanes. The stability of the RF system is critical in setting up the position to energy correlation. Specifications derived from simulations require the RF system to be stable to below 200fS in several critical injector stations and the last kilometer of linac. The SLAC linac RF system is being upgraded to meet these requirements. used to accelerate the beam to 4.3GeV before entering BC2. Linac 3, klystron stations 25-1 to 30-8, accelerates the beam to 13.6GeV

    Foraging niche separation of social wasps in an invaded area: Implications for their management

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    Foraging niche separation may be a mechanism to promote coexistence of two competing species by concentrating intraspecific competition relative to interspecific competition. The present study investigated foraging behaviour and microhabitat use of two coexisting species of invasive social wasps, Vespula germanica and Vespula vulgaris, when foraging for two different food resources. Also, we tested the attractiveness of traps baited with a synthetic lure for those two species. We found that V. germanica wasps prefer to forage at ground level regardless of the resource, while V. vulgaris prefers protein resources at the shrubland level given a choice between a protein bait at ground or at shrubland level. However, when baited with the synthetic lure, the species caught was not affected by the height at which traps were placed. That is, in a no choice scenario, the traps were sufficiently attractive to lure both species of wasps to both microhabitats (ground and shrubland levels). Thus, our results support the existence of spatial niche differentiation at least in protein foraging and suggest that the synthetic lure evaluated could be used to trap both species of Vespula wasps present in Argentina. These results could help to improve management strategies of these social wasps in an invaded area.Estación Experimental Agropecuaria BarilocheFil: Masciocchi, Maite. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituo de Investigaciones Forestales y Agropecuarias Bariloche. Grupo de Ecología de Poblaciones de Insectos; ArgentinaFil: Unelius, Carl Rikard. Linnaeus University. Faculty of Health and Life Sciences; SueciaFil: Buteler, Micaela. Universidad Nacional del Comahue. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones en Biodiversidad y Medio Ambiente; Argentin

    Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

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    For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin burn propagation into surrounding cold fuel, enabling the possibility of high energy gain. While scientific breakeven (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

    Epstein–Barr virus antibody level and gastric cancer risk in Korea: a nested case–control study

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    BACKGROUND: Few cohort studies have investigated Epstein-Barr virus (EBV) infection before the occurrence of gastric cancer. METHODS: Among 14 440 cohort participants, 100 incident gastric cancer cases were individually matched to two controls. Epstein-Barr virus antibodies IgG and IgA against viral capsid antigen (VCA), EBV nuclear antigen (EBNA) antibody IgG, and early antigen (EA) antibody IgG were measured using enzyme immunoassays (EIAs). RESULTS: The highest titres of VCA IgG (odds ratio (OR): 1.37, 95% confidence interval (CI): 0.62-3.06) or EBNA IgG (OR: 0.87, 95% CI: 0.51-1.46) were not associated with gastric cancer risk. CONCLUSION: Higher levels of VCA IgG or EBNA IgG were not associated with increased risk of gastric adenocarcinoma in Koreans.Akiba S, 2008, CANCER SCI, V99, P195, DOI 10.1111/j.1349-7006.2007.00674.xKoshiol J, 2007, BRIT J CANCER, V97, P1567, DOI 10.1038/sj.bjc.6604063Tedeschi R, 2007, AM J EPIDEMIOL, V165, P134, DOI 10.1093/aje/kwj332Gwack J, 2006, BRIT J CANCER, V95, P639, DOI 10.1038/sj.bjc.6603309Ouburg S, 2005, EUR J GASTROEN HEPAT, V17, P1213Chan D, 2005, J RES PRACT INF TECH, V37, P267HERRERAGOEPFERT R, 2005, WORLD J GASTROENTERO, V11, P6096CORREA P, 2004, GASTRIC CANCER, V7, P9Macsween KF, 2003, LANCET INFECT DIS, V3, P131Gartner BC, 2003, CLIN DIAGN LAB IMMUN, V10, P78, DOI 10.1128/CDLI.10.1.78-82.2003Burgess DE, 2002, BRIT J CANCER, V86, P702, DOI 10.1038/sj/bjc/6600107YOO KY, 2002, ASIAN PAC J CANCER P, V3, P85Chien YC, 2001, NEW ENGL J MED, V345, P1877Bruu AL, 2000, CLIN DIAGN LAB IMMUN, V7, P451Shinkura R, 2000, J MED VIROL, V60, P411Akre O, 1999, INT J CANCER, V82, P1Tokunaga M, 1998, CANCER EPIDEM BIOMAR, V7, P449*IARC, 1997, EPSTEINBARR VIR KAP, V8LEVINE PH, 1995, INT J CANCER, V60, P642LEHTINEN T, 1993, CANCER CAUSE CONTROL, V4, P187GESER A, 1982, INT J CANCER, V29, P397

    TRY plant trait database - enhanced coverage and open access

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    Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
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