43 research outputs found

    Antiproton Production in p+Ap+A Collisions at AGS Energies

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    Inclusive and semi-inclusive measurements are presented for antiproton (pˉ\bar{p}) production in proton-nucleus collisions at the AGS. The inclusive yields per event increase strongly with increasing beam energy and decrease slightly with increasing target mass. The pˉ\bar{p} yield in 17.5 GeV/c p+Au collisions decreases with grey track multiplicity, NgN_g, for Ng>0N_g>0, consistent with annihilation within the target nucleus. The relationship between NgN_g and the number of scatterings of the proton in the nucleus is used to estimate the pˉ\bar{p} annihilation cross section in the nuclear medium. The resulting cross section is at least a factor of five smaller than the free pˉ−p\bar{p}-p annihilation cross section when assuming a small or negligible formation time. Only with a long formation time can the data be described with the free pˉ−p\bar{p}-p annihilation cross section.Comment: 8 pages, 6 figure

    Semi-Inclusive Lambda and Kshort Production in p-Au Collisions at 17.5 GeV/c

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    The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Lambda and Kshort dn/dy distributions from 17.5 GeV/c p-Au collisions are shown as a function of "grey" track multiplicity and the estimated number of collisions, nu, made by the proton. The nu dependence of the Lambda yield deviates from a scaling of p-p data by the number of participants, increasing faster than this scaling for nu<=5 and saturating for larger nu. A slower growth in Kshort multiplicity with nu is observed, consistent with a weaker nu dependence of K-Kbar production than Y-K production.Comment: 5 pages, 3 figures, formatted with RevTex, current version has enlarged figure catpion

    Slit2–Robo4 signalling promotes vascular stability by blocking Arf6 activity

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    Slit–Roundabout (Robo) signalling has a well-understood role in axon guidance1–5. Unlike in the nervous system, however, Slitdependent activation of an endothelial-specific Robo, Robo4, does not initiate a guidance program. Instead, Robo4 maintains the barrier function of the mature vascular network by inhibiting neovascular tuft formation and endothelial hyperpermeability induced by pro-angiogenic factors 6. In this study, we used cell biological and biochemical techniques to elucidate the molecular mechanism underlying the maintenance of vascular stability by Robo4. Here, we demonstrate that Robo4 mediates Slit2-dependent suppression of cellular protrusive activity through direct interaction with the intracellular adaptor protein paxillin and its paralogue, Hic-5. Formation of a Robo4–paxillin complex at the cell surface blocks activation of the small GTPase Arf6 and, consequently, Rac by recruitment of Arf-GAPs (ADP-ribosylation factor- directed GTPase-activating proteins) such as GIT1. Consistent with these in vitro studies, inhibition of Arf6 activity in vivo phenocopies Robo4 activation by reducing pathologic angiogenesis in choroidal and retinal vascular disease and VEGF-165 (vascular endothelial growth factor-165)-induced retinal hyperpermeability. These data reveal that a Slit2–Robo4–paxillin–GIT1 network inhibits the cellular protrusive activity underlying neovascularization and vascular leak, and identify a new therapeutic target for ameliorating diseases involving the vascular system

    The PHENIX Experiment at RHIC

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    The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

    Deliverable 1.1 review document on the management of marine areas with particular regard on concepts, objectives, frameworks and tools to implement, monitor, and evaluate spatially managed areas

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    The main objectives if this document were to review the existing information on spatial management of marine areas, identifying the relevant policy objectives, to identify parameters linked to the success or failure of the various Spatially Managed marine Areas (SMAs) regimes, to report on methods and tools used in monitoring and evaluation of the state of SMAs, and to identify gaps and weaknesses in the existing frameworks in relation to the implementation, monitoring, evaluation and management of SMAs. The document is naturally divided in two sections: Section 1 reviews the concepts, objectives, drivers, policy and management framework, and extraneous factors related to the design, implementation and evaluation of SMAs; Section 2 reviews the tools and methods to monitor and evaluate seabed habitats and marine populations.peer-reviewe

    Deliverable 3.6 zoning plan of case studies : evaluation of spatial management options for the case studies

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    Within MESMA, nine case studies (CS) represent discrete marine European spatial entities, at different spatial scales, where a spatial marine management framework is in place, under development or considered. These CS (described in more details below) are chosen in such a way (MESMA D. 3.1 ) that they encompass the complexity of accommodating the various user functions of the marine landscape in various regions of the European marine waters. While human activities at sea are competing for space, there is also growing awareness of the possible negative effects of these human activities on the marine ecosystem. As such, system specific management options are required, satisfying current and future sectoral needs, while safeguarding the marine ecosystem from further detoriation. This integrated management approach is embedded in the concept of ecosystem based management (EBM). The goal of marine EBM is to maintain marine ecosystems in a healthy, productive and resilient condition, making it possible that they sustain human use and provide the goods and services required by society (McLeod et al. 2005). Therefore EBM is an environmental mangagement approach that recognises the interactions within a marine ecosystem, including humans. Hence, EBM does not consider single issues, species or ecosystems good and services in isolation. Operationalisation of EBM can be done through place-based or spatial management approaches (Lackey 1998), such as marine spatial planning (MSP). MSP is a public process of analysing and allocating the spatial and temporal distribution of human activities aiming at achieving ecological, economic and social objectives. These objectives are usually formulated through political processes (Douvere et al. 2007, Douvere 2008). Within MESMA, a spatially managed area (SMA) is then defined as “a geographical area within which marine spatial planning initiatives exist in the real world”. Marine spatial planning initiatives refer to existing management measures actually in place within a defined area, or in any stage of a process of putting management in place, e.g. plans or recommendations for a particular area. Management can include management for marine protection (e.g. in MPAs), or management for sectoral objectives (e.g. building a wind farm to meet renewable energy objectives). Within MESMA, SMAs can have different spatial scales. A SMA can be a small, specific area that is managed/planned to be managed for one specific purpose, but it can also be a larger area within which lots of plans or ‘usage zones’ exist. This definition is different from the definition mentioned in the DoW (page 60). The original definition was adapted during a CS leader workshop (2-4 May 2012 in Gent, Belgium) and formally accepted by the MESMA ExB during the ExB meeting in Cork (29-30 May 2012). MSP should result in a marine spatial management plan that will produce the desired future trough explicit decisions about the location and timing of human activities. Ehler & Douvere (2009) consider this spatial management as a beginning toward the the implementation of desired goals and objectives. They describe the spatial management plan as a comprehensive, strategic document that provides the framework and direction for marine spatial management decisions. The plan should identify when, where and how goals and objectives will be met. Zoning (the development of zoning plans) is often an important management measure to implement spatial management plans. The purpose of a zoning plan (Ehler & Douvere 2009) is: To provide protection for biologically and ecologically important habitats, ecosystems, and ecological processes. To seperate conflicting human activities, or to combine compatible activities. To protect the natural values of the marine management area (in MESMA terminology: the SMA) while allowing reasonable human uses of the area. To allocate areas for reasonable human uses while minimising the effects of these human uses on each other, and nature. To preserve some areas of the SMA in their natural state undisturbed by humans except for scientific and educational purposes.peer-reviewe
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