214 research outputs found

    DIstributed VIRtual System (DIVIRS) Project

    Get PDF
    The development of Prospero moved from the University of Washington to ISI and several new versions of the software were released from ISI during the contract period. Changes in the first release from ISI included bug fixes and extensions to support the needs of specific users. Among these changes was a new option to directory queries that allows attributes to be returned for all files in a directory together with the directory listing. This change greatly improves the performance of their server and reduces the number of packets sent across their trans-pacific connection to the rest of the internet. Several new access method were added to the Prospero file method. The Prospero Data Access Protocol was designed, to support secure retrieval of data from systems running Prospero

    An Investigation Into Alternative Television Viewership Habits Of College Students

    Get PDF
    Television viewership through the use of digital video recorders (DVRs) and the Internet are affecting viewership statistics. The utilization of the Internet by students to view television programs mandates that future marketing efforts be directed more toward the Internet instead of traditional television advertisements.  Research focused on the television viewing habits of college students, current challenges in television advertising and marketing and the increasing use of DVRs and the Internet are investigated

    From network structure to network reorganization: implications for adult neurogenesis

    Full text link
    Networks can be dynamical systems that undergo functional and structural reorganization. One example of such a process is adult hippocampal neurogenesis, in which new cells are continuously born and incorporate into the existing network of the dentate gyrus region of the hippocampus. Many of these introduced cells mature and become indistinguishable from established neurons, joining the existing network. Activity in the network environment is known to promote birth, survival and incorporation of new cells. However, after epileptogenic injury, changes to the connectivity structure around the neurogenic niche are known to correlate with aberrant neurogenesis. The possible role of network-level changes in the development of epilepsy is not well understood. In this paper, we use a computational model to investigate how the structural and functional outcomes of network reorganization, driven by addition of new cells during neurogenesis, depend on the original network structure. We find that there is a stable network topology that allows the network to incorporate new neurons in a manner that enhances activity of the persistently active region, but maintains global network properties. In networks having other connectivity structures, new cells can greatly alter the distribution of firing activity and destroy the initial activity patterns. We thus find that new cells are able to provide focused enhancement of network only for small-world networks with sufficient inhibition. Network-level deviations from this topology, such as those caused by epileptogenic injury, can set the network down a path that develops toward pathological dynamics and aberrant structural integration of new cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85406/1/ph10_4_046008.pd

    The role of cell-cell adhesion in wound healing

    Full text link
    We present a stochastic model which describes fronts of cells invading a wound. In the model cells can move, proliferate, and experience cell-cell adhesion. We find several qualitatively different regimes of front motion and analyze the transitions between them. Above a critical value of adhesion and for small proliferation large isolated clusters are formed ahead of the front. This is mapped onto the well-known ferromagnetic phase transition in the Ising model. For large adhesion, and larger proliferation the clusters become connected (at some fixed time). For adhesion below the critical value the results are similar to our previous work which neglected adhesion. The results are compared with experiments, and possible directions of future work are proposed.Comment: to appear in Journal of Statistical Physic

    Arctic deep water ferromanganese-oxide deposits reflect the unique characteristics of the Arctic Ocean

    Get PDF
    Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 18 (2017): 3771–3800, doi:10.1002/2017GC007186.Little is known about marine mineral deposits in the Arctic Ocean, an ocean dominated by continental shelf and basins semi-closed to deep-water circulation. Here, we present data for ferromanganese crusts and nodules collected from the Amerasia Arctic Ocean in 2008, 2009, and 2012 (HLY0805, HLY0905, and HLY1202). We determined mineral and chemical compositions of the crusts and nodules and the onset of their formation. Water column samples from the GEOTRACES program were analyzed for dissolved and particulate scandium concentrations, an element uniquely enriched in these deposits. The Arctic crusts and nodules are characterized by unique mineral and chemical compositions with atypically high growth rates, detrital contents, Fe/Mn ratios, and low Si/Al ratios, compared to deposits found elsewhere. High detritus reflects erosion of submarine outcrops and North America and Siberia cratons, transport by rivers and glaciers to the sea, and distribution by sea ice, brines, and currents. Uniquely high Fe/Mn ratios are attributed to expansive continental shelves, where diagenetic cycling releases Fe to bottom waters, and density flows transport shelf bottom water to the open Arctic Ocean. Low Mn contents reflect the lack of a mid-water oxygen minimum zone that would act as a reservoir for dissolved Mn. The potential host phases and sources for elements with uniquely high contents are discussed with an emphasis on scandium. Scandium sorption onto Fe oxyhydroxides and Sc-rich detritus account for atypically high scandium contents. The opening of Fram Strait in the Miocene and ventilation of the deep basins initiated Fe-Mn crust growth ∼15 Myr ago.National Science Foundation Grant Numbers: 1434493, 1713677; NSF-OCE Grant Number: 15358542018-05-0

    Heterogenous mean-field analysis of a generalized voter-like model on networks

    Get PDF
    We propose a generalized framework for the study of voter models in complex networks at the the heterogeneous mean-field (HMF) level that (i) yields a unified picture for existing copy/invasion processes and (ii) allows for the introduction of further heterogeneity through degree-selectivity rules. In the context of the HMF approximation, our model is capable of providing straightforward estimates for central quantities such as the exit probability and the consensus/fixation time, based on the statistical properties of the complex network alone. The HMF approach has the advantage of being readily applicable also in those cases in which exact solutions are difficult to work out. Finally, the unified formalism allows one to understand previously proposed voter-like processes as simple limits of the generalized model

    Neuronal wiring diagram of an adult brain

    Get PDF
    Connections between neurons can be mapped by acquiring and analysing electron microscopic brain images. In recent years, this approach has been applied to chunks of brains to reconstruct local connectivity maps that are highly informative1–6, but nevertheless inadequate for understanding brain function more globally. Here we present a neuronal wiring diagram of a whole brain containing 5 × 107 chemical synapses7 between 139,255 neurons reconstructed from an adult female Drosophila melanogaster8, 9. The resource also incorporates annotations of cell classes and types, nerves, hemilineages and predictions of neurotransmitter identities10–12. Data products are available for download, programmatic access and interactive browsing and have been made interoperable with other fly data resources. We derive a projectome—a map of projections between regions—from the connectome and report on tracing of synaptic pathways and the analysis of information flow from inputs (sensory and ascending neurons) to outputs (motor, endocrine and descending neurons) across both hemispheres and between the central brain and the optic lobes. Tracing from a subset of photoreceptors to descending motor pathways illustrates how structure can uncover putative circuit mechanisms underlying sensorimotor behaviours. The technologies and open ecosystem reported here set the stage for future large-scale connectome projects in other species

    Ecological, Economic and Policy Alternatives for Texas Rice Agriculture

    Get PDF
    An interdisciplinary research team, working in collaboration with and under the auspices of the Institute for Science, Technology and Public Policy in the George Bush School of Government and Public Service at Texas A&M University, conducted a two-year research project entitled Ecological, Economic, and Policy Alternatives for Texas Rice Agriculture. This project was sponsored by the Texas Water Resources Institute (TWRI). Principal investigators were Dr. Letitia T. Alston, Dr. Thomas E. Lacher, Dr. R. Douglas Slack, Dr. Arnold Vedlitz, and Dr. Richard T. Woodward. They were assisted by Dr. James C. Franklin, post-doctoral research associate, and the following research assistants: Nicole Canzoneri, April Ann Torres Conkey, Deborah F. Cowman, Jeanine Harris, April Henry, Elizabeth Iennedy, Michelle Irohn, Ielly Mizell, Jill Nicholson, Kelly Tierce, and Yong-Suhk Wui. The objectives of this research were: (1) to develop a reliable first estimate of the environmental consequences of reduction in rice acreage; (2) to analyze economic consequences of changes in rice acreage that may occur due to the changes in the system of price supports; and (3) to critically review existing policy and explore the kinds of institutional arrangements that might be developed to encourage the preservation of the environmental amenities provided by rice farming

    The Ol1mpiad: concordance of behavioural faculties of stage 1 and stage 3 Drosophila larvae

    Get PDF
    This publication hasn't any creative commons license associated. This article has a Company of Biologists User Licence 1.1. The deposited article version contains attached the supplementary materials within the pdf.Mapping brain function to brain structure is a fundamental task for neuroscience. For such an endeavour, the Drosophila larva is simple enough to be tractable, yet complex enough to be interesting. It features about 10,000 neurons and is capable of various taxes, kineses and Pavlovian conditioning. All its neurons are currently being mapped into a light-microscopical atlas, and Gal4 strains are being generated to experimentally access neurons one at a time. In addition, an electron microscopic reconstruction of its nervous system seems within reach. Notably, this electron microscope-based connectome is being drafted for a stage 1 larva - because stage 1 larvae are much smaller than stage 3 larvae. However, most behaviour analyses have been performed for stage 3 larvae because their larger size makes them easier to handle and observe. It is therefore warranted to either redo the electron microscopic reconstruction for a stage 3 larva or to survey the behavioural faculties of stage 1 larvae. We provide the latter. In a community-based approach we called the Ol1mpiad, we probed stage 1 Drosophila larvae for free locomotion, feeding, responsiveness to substrate vibration, gentle and nociceptive touch, burrowing, olfactory preference and thermotaxis, light avoidance, gustatory choice of various tastants plus odour-taste associative learning, as well as light/dark-electric shock associative learning. Quantitatively, stage 1 larvae show lower scores in most tasks, arguably because of their smaller size and lower speed. Qualitatively, however, stage 1 larvae perform strikingly similar to stage 3 larvae in almost all cases. These results bolster confidence in mapping brain structure and behaviour across developmental stages.Fundação para a Ciência e a Tecnologia grants: (SFRH/BPD/75993/2011EXPL/BEX-BID/0497/2013); Cluster of Excellence Cells in Motion; CiM International Max Planck research school; Spanish Ministry of Economy and Competitiveness; ‘Centro de Excelencia Severo Ochoa 2013-2017’ grant: (SEV-2012-0208); CERCA Programme/Generalitat de Catalunya; the ‘la Caixa’ International PhD Programme; Spanish Ministry of Science and Innovation grant: (BFU2011-26208); Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz; State of Sachsen-Anhalt; Center for Behavioral Brain Sciences Magdeburg; Otto von Guericke Universität Magdeburg; Deutsche Forschungsgemeinschaft grants: (CRC 779 Motivated behaviour: B11; GE1091/4-1, SPP 1926, Next generation optogenetics, SO1337/2-1, CRC 779 Motivated behaviour: B15; YA272/2-1, PA 787/7-1, (TH1584/1-1, TH1584/3-1); European Commission grant: (FP7-ICT project Miniature Insect Model for Active Learning MINIMAL); Howard Hughes Medical Institute; European Research Council grant: (ERC-2012-StG 309832-PhotoNaviNet); Swiss National Science Foundation grant: (31003A_169993); Landesforschungsförderung Hamburg grant: (LFF-FV27); Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz; State of Sachsen-Anhalt; Center for Behavioral Brain Sciences Magdeburg; Cluster of Excellence ImmunoSensation; Baden-Württemberg Stiftung; Zukunftskolleg of the University of Konstanz.info:eu-repo/semantics/publishedVersio
    • …
    corecore