492 research outputs found

    Where were they from? Modelling the source stock of dolphins stranded after the Deepwater Horizon oil spill using genetic and stable isotope data

    Get PDF
    Understanding the source stock of common bottlenose dolphins Tursiops truncatus that stranded in the northern Gulf of Mexico subsequent to the Deepwater Horizon oil spill was essential to accurately quantify injury and apportion individuals to the appropriate stock. The aim of this study, part of the Natural Resource Damage Assessment (NRDA), was to estimate the proportion of the 932 recorded strandings between May 2010 and June 2014 that came from coastal versus bay, sound and estuary (BSE) stocks. Four sources of relevant information were available on overlapping subsets totaling 336 (39%) of the strandings: genetic stock assignment, stable isotope ratios, photo-ID and individual genetic-ID. We developed a hierarchical Bayesian model for combining these sources that weighted each data source for each stranding according to a measure of estimated precision: the effective sample size (ESS). The photo- and genetic-ID data were limited and considered to potentially introduce biases, so these data sources were excluded from analyses used in the NRDA. Estimates were calculated separately in 3 regions: East (of the Mississippi outflow), West (of the Mississippi outflow through Vermilion Bay, Louisiana) and Western Louisiana (west of Vermilion Bay to the Texas-Louisiana border); the estimated proportions of coastal strandings were, respectively 0.215 (95% CI: 0.169-0.263), 0.016 (0.036-0.099) and 0.622 (0.487-0.803). This method represents a general approach for integrating multiple sources of information that have differing uncertainties.Publisher PDFPeer reviewe

    Direct, biomimetic synthesis of (+)-artemone via a stereoselective, organocatalytic cyclization

    Get PDF
    We present a four-step synthesis of (+)-artemone from (–)- linalool, featuring iminium organocatalysis of a doubly diastereoselective conjugate addition reaction. The strategy follows a proposed biosynthetic pathway, rapidly generates stereochemical complexity, uses no protecting groups, and minimizes redox manipulations

    Characterizing the diverse cells that associate with the developing commissures of the zebrafish forebrain

    Get PDF
    During embryonic development of bilaterally symmetrical organisms, neurons send axons across the midline at specific points to connect the two halves of the nervous system with a commissure. Little is known about the cells at the midline that facilitate this tightly regulated process. We exploit the conserved process of vertebrate embryonic development in the zebrafish model system to elucidate the identity of cells at the midline that may facilitate postoptic (POC) and anterior commissure (AC) development. We have discovered that three different gfap+ astroglial cell morphologies persist in contact with pathfinding axons throughout commissure formation. Similarly, olig2+ progenitor cells occupy delineated portions of the postoptic and anterior commissures where they act as multipotent, neural progenitors. Moreover, we conclude that both gfap+ and olig2+ progenitor cells give rise to neuronal populations in both the telencephalon and diencephalon; however, these varied cell populations showed significant developmental timing differences between the telencephalon and diencephalon. Lastly, we also showed that fli1a+ mesenchymal cells migrate along the presumptive commissure regions before and during midline axon crossing. Furthermore, following commissure maturation, specific blood vessels formed at the midline of the POC and immediately ventral and parallel to the AC. This comprehensive account of the cellular populations that correlate with the timing and position of commissural axon pathfinding has supported the conceptual modeling and identification of the early forebrain architecture that may be necessary for proper commissure development

    The band structure of BeTe - a combined experimental and theoretical study

    Full text link
    Using angle-resolved synchrotron-radiation photoemission spectroscopy we have determined the dispersion of the valence bands of BeTe(100) along ΓX\Gamma X, i.e. the [100] direction. The measurements are analyzed with the aid of a first-principles calculation of the BeTe bulk band structure as well as of the photoemission peaks as given by the momentum conserving bulk transitions. Taking the calculated unoccupied bands as final states of the photoemission process, we obtain an excellent agreement between experimental and calculated spectra and a clear interpretation of almost all measured bands. In contrast, the free electron approximation for the final states fails to describe the BeTe bulk band structure along ΓX\Gamma X properly.Comment: 21 pages plus 4 figure

    The development of the British Red Cross' psychosocial framework: 'calmer'

    Get PDF
    This paper presents the history, development and approach of the new psychosocial framework which in 2008 was adopted by the British Red Cross, and a piece of research designed to review its fitness for purpose as an educational tool. The framework CALMER is a single, overarching approach for considering and delivering psychosocial services across all of the British Red Cross. It is being included in all relevant training programmes, such as within first aid and psychosocial support and within services in emergency response, event first aid, health and social care, international tracing and message and refugee services and across human resources. The framework includes six prompts which should be followed sequentially, with guidance on facilitative behaviours within each. The research considered the levels of confidence and worry of participants on one day training programmes delivered to three different groups of personnel in three different countries. While finding support for the CALMER framework, further recommendations are made for future research

    A new degree of freedom for memory allocation in clusters

    Full text link
    Improvements in parallel computing hardware usually involve increments in the number of available resources for a given application such as the number of computing cores and the amount of memory. In the case of shared-memory computers, the increase in computing resources and available memory is usually constrained by the coherency protocol, whose overhead rises with system size, limiting the scalability of the final system. In this paper we propose an efficient and cost-effective way to increase the memory available for a given application by leveraging free memory in other computers in the cluster. Our proposal is based on the observation that many applications benefit from having more memory resources but do not require more computing cores, thus reducing the requirements for cache coherency and allowing a simpler implementation and better scalability. Simulation results show that, when additional mechanisms intended to hide remote memory latency are used, execution time of applications that use our proposal is similar to the time required to execute them in a computer populated with enough local memory, thus validating the feasibility of our proposal. We are currently building a prototype that implements our ideas. The first results from real executions in this prototype demonstrate not only that our proposal works but also that it can efficiently execute applications that make use of remote memory resources. © 2011 Springer Science+Business Media, LLC.This work has been supported by PROMETEO from Generalitat Valenciana (GVA) under Grant PROMETEO/2008/060.Montaner Mas, H.; Silla Jiménez, F.; Fröning, H.; Duato Marín, JF. (2012). A new degree of freedom for memory allocation in clusters. Cluster Computing. 15(2):101-123. https://doi.org/10.1007/s10586-010-0150-7S1011231523leaf Systems: http://www.3leafsystems.comAcharya, A., Setia, S.: Availability and utility of idle memory in workstation clusters. ACM SIGMETRICS Perform. Eval. Rev. 27(1), 35–46 (1999). doi: 10.1145/301464.301478Anderson, T., Culler, D., Patterson, D.: A case for NOW (Networks of Workstations). IEEE MICRO 15(1), 54–64 (1995). doi: 10.1109/40.342018HyperTransport Technology Consortium. HyperTransport I/O Link Specification Revision 3.10 (2008). Available at http://www.hypertransport.orgBienia, C., Kumar, S., et al.: The parsec benchmark suite: Characterization and architectural implications. In: Proceedings of the 17th PACT (2008)Chapman, M., Heiser, G.: vNUMA: A virtual shared-memory multiprocessor. In: Proceedings of the 2009 USENIX Annual Technical Conference, San Diego, USA, 2000, pp. 349–362. (2009)Charles, P., Grothoff, C., Saraswat, V., et al.: X10: an object-oriented approach to non-uniform cluster computing. ACM SIGPLAN Not. 40(10), 519–538 (2005)Consortium, H.: HyperTransport High Node Count, Slides. http://www.hypertransport.org/default.cfm?page=HighNodeCountSpecificationConway, P., Hughes, B.: The AMD opteron northbridge architecture. IEEE MICRO 27(2), 10–21 (2007). doi: 10.1109/MM.2007.43Conway, P., Kalyanasundharam, N., Donley, G., et al.: Blade computing with the AMD Opteron processor (Magny-Cours). Hot chips 21 (2009)Duato, J., Silla, F., Yalamanchili, S., et al.: Extending HyperTransport protocol for improved scalability. First International Workshop on HyperTransport Research and Applications (2009)Feeley, M.J., Morgan, W.E., Pighin, E.P., Karlin, A.R., Levy, H.M., Thekkath, C.A.: Implementing global memory management in a workstation cluster. In: SOSP ’95: Proceedings of the Fifteenth ACM Symposium on Operating Systems Principles, pp. 201–212. ACM, New York (1995). doi: 10.1145/224056.224072Fröning, H., Litz, H.: Efficient hardware support for the partitioned global address space. In: 10th Workshop on Communication Architecture for Clusters (2010)Fröning, H., Nuessle, M., Slogsnat, D., Litz, H., Brüening, U.: The HTX-board: a rapid prototyping station. In: 3rd annual FPGAworld Conference (2006)Garcia-Molina, H., Salem, K.: Main memory database systems: an overview. IEEE Trans. Knowl. Data Eng. 4(6), 509–516 (1992). doi: 10.1109/69.180602Gaussian 03: http://www.gaussian.comGray, J., Liu, D.T., Nieto-Santisteban, M., et al.: Scientific data management in the coming decade. SIGMOD Rec. 34(4), 34–41 (2005). doi: 10.1145/1107499.1107503IBM journal of Research and Development staff: Overview of the IBM Blue Gene/P project. IBM J. Res. Dev. 52(1/2), 199–220 (2008)IBM z Series: http://www.ibm.com/systems/zIn-Memory Database Systems (IMDSs) Beyond the Terabyte Size Boudary: http://www.mcobject.com/130/EmbeddedDatabaseWhitePapers.htmKeltcher, C., McGrath, K., Ahmed, A., Conway, P.: The AMD opteron processor for multiprocessor servers. Micro IEEE 23(2), 66–76 (2003). doi: 10.1109/MM.2003.1196116Kottapalli, S., Baxter, J.: Nehalem-EX CPU architecture. Hot chips 21 (2009)Liang, S., Noronha, R., Panda, D.: Swapping to remote memory over infiniband: an approach using a high performance network block device. In: Cluster Computing, 2005. IEEE International, pp. 1–10. (2005) doi: 10.1109/CLUSTR.2005.347050Litz, H., Fröning, H., Nuessle, M., Brüening, U.: A hypertransport network interface controller for ultra-low latency message transfers. HyperTransport Consortium White Paper (2007)Litz, H., Fröning, H., Nuessle, M., Brüening, U.: VELO: A novel communication engine for ultra-low latency message transfers. In: 37th International Conference on Parallel Processing, 2008. ICPP ’08, pp. 238–245 (2008). doi: 10.1109/ICPP.2008.85Magnusson, P., Christensson, M., Eskilson, J., et al.: Simics: a full system simulation platform. Computer 35(2), 50–58 (2002). doi: 10.1109/2.982916Martin, M., Sorin, D., Beckmann, B., et al.: Multifacet’s general execution-driven multiprocessor simulator (GEMS) toolset. ACM SIGARCH Comput. Archit. News 33(4), 92–99 (2005) doi: 10.1145/1105734.1105747MBA3 NC Series Catalog: http://www.fujitsu.com/global/services/computing/storage/hdd/ehdd/mba3073nc-mba3300nc.htmlMcCalpin, J.D.: Memory bandwidth and machine balance in current high performance computers. In: IEEE Computer Society Technical Committee on Computer Architecture (TCCA) Newsletter, pp. 19–25 (1995)NUMAChip: http://www.numachip.com/Oguchi, M., Kitsuregawa, M.: Using available remote memory dynamically for parallel data mining application on ATM-connected PC cluster. In: IPDPS 2000. Proceedings, 14th International, pp. 411–420 (2000). doi: 10.1109/IPDPS.2000.846014Oleszkiewicz, J., Xiao, L., Liu, Y.: Parallel network RAM: effectively utilizing global cluster memory for large data-intensive parallel programs. In: International Conference on Parallel Processing, 2004. ICPP 2004, vol. 1, pp. 353–360 (2004). doi: 10.1109/ICPP.2004.1327942Ronstrom, M., Thalmann, L.: MySQL cluster architecture overview. Technical White Paper. MySQL (2004)ScaleMP: http://www.scalemp.comSGI: Technical advances in the SGI Altix UV architecture, White Paper. http://www.sgi.com/products/servers/altix/uv/Slogsnat, D., Giese, A., Nüssle, M., Brüning, U.: An open-source HyperTransport core. ACM Trans. Reconfigurable Technol. Syst. 1(3), 1–21 (2008). doi: 10.1007/s10586-010-0150-7Szalay, A.S., Gray, J., vandenBerg, J.: Petabyte Scale Data Mining: Dream or Reality? CoRR cs.DB/0208013 (2002)Tuck, J., Ceze, L., Torrellas, J.: Scalable cache miss handling for high memory-level parallelism. In: Microarchitecture, 2006. MICRO-39. 39th Annual IEEE/ACM International Symposium on (2006)Violin Memory: http://violin-memory.comDynamic Logical Partitioning. White Paper: http://www.ibm.com/systems/p/hardware/whitepapers/dlpar.htmlYelick, K.: Computer architecture: Opportunities and challenges for scalable applications. Sandia CSRI Workshop on Next-generation scalable applications: When MPI-only is not enough (2008)Yelick, K.: Programming models: Opportunities and challenges for scalable applications. Sandia CSRI Workshop on Next-generation scalable applications: When MPI-only is not enough (2008

    Binding Energy of Charged Excitons in ZnSe-based Quantum Wells

    Full text link
    Excitons and charged excitons (trions) are investigated in ZnSe-based quantum well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of magneto-optical spectroscopy. Binding energies of negatively () and positively (X+) charged excitons are measured as functions of quantum well width, free carrier density and in external magnetic fields up to 47 T. The binding energy of shows a strong increase from 1.4 to 8.9 meV with decreasing quantum well width from 190 to 29 A. The binding energies of X+ are about 25% smaller than the binding energy in the same structures. The magnetic field behavior of and X+ binding energies differ qualitatively. With growing magnetic field strength, increases its binding energy by 35-150%, while for X+ it decreases by 25%. Zeeman spin splittings and oscillator strengths of excitons and trions are measured and discussed
    corecore