254 research outputs found

    Understanding the Brain through Neuroinformatics

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    INCF -- new capability for global coordination in neuroinformatics

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    The Global Science Forum (GSF) of the OECD has initiated a new international organization, INCF, to further the development of Neuroinformatics as a global effort with the support of all ministers of research within OECD. This presentation explains the background for the establishment of the INCF, outlines some of the goals, and defines the operations of the INCF Secretariat in relation the INCF National nodes and the general neuroscience community

    Topography of the complete corticopontine projection: From experiments to principal Maps

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    The mammalian brain is characterized by orderly spatial distribution of its cellular components, commonly referred to as topographical organization. The topography of cortical and subcortical maps is thought to represent functional or computational properties. In the present investigation, we have studied map transformations and organizing principles in the projections from the cerebral cortex to the pontine nuclei, with emphasis on the mapping of the cortex as a whole onto the pontine nuclei. Following single or multiple axonal tracer injections into different cortical regions, three-dimensional (3-D) distributions of anterogradely labeled axons in the pontine nuclei were mapped. All 3-D reconstructed data sets were normalized to a standardized local coordinate system for the pontine nuclei and uploaded in a database application (FACCS, Functional Anatomy of the Cerebro-Cerebellar System, available via The Rodent Brain Workbench, http://www.rbwb.org). The database application allowed flexible use of the data in novel combinations, and use of a previously published data sets. Visualization of different combinations of data was used to explore alternative principles of organization. As a result of these analyses, a principal map of the topography of corticopontine projections was developed. This map followed the organization of early spatiotemporal gradients present in the cerebral cortex and the pontine nuclei. With the principal map for corticopontine projections, a fairly accurate prediction of pontine target area can be made for any site of origin in the cerebral cortex. The map and the underlying shared data sets represent a basis for modeling of topographical organization and structure–function relationships in this system

    Understanding and engineering two-dimensional electron gases in complex oxides

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    The next generation of electronic devices faces the challenge of adequately containing and controlling extremely high charge densities within structures of nanometer dimensions. Atomic-scale transistors must be thin and be able to control extremely high charge densities (>10e13/cm^2). Silicon devices typically have two-dimensional electron gas (2DEG) densities around 10e12/cm^2. Nitride-based devices can sustain densities an order of magnitude higher. The "complex oxides" have recently emerged as an attractive materials system to support these developments. The demonstration of a 2DEG at the SrTiO3/LaAlO3 interface has triggered an avalanche of research, including the unprecedentedly high density of 3x10e14/cm^2 at SrTiO3/GdTiO3 and SrTiO3/SmTiO3 interfaces. Metal-insulator (Mott) transitions that are inherent to some of these complex oxides could offer even greater prospects for enhanced functionality or novel device concepts.The materials and heterostructures that have been explored to date are clearly only a small subset of the vast number of materials combinations that could lead to interesting phenomena. In this work we use first-principles methods to build greater understanding of the interface phenomena, so that searches can be better informed and more focused. We also develop a set of criteria that the materials and their heterostructures should satisfy to develop a high-performance 2DEG-based device. We focus in particular on the band alignment, calculating it for a variety of different potential materials. Next, we study GdTiO3/SrTiO3/GdTiO3 heterostructures in depth, where each interface contributes excess electrons into the SrTiO3. We calculate the 2DEG formation for a superlattice containing six layers of SrTiO3, and compare with angle-resolved photoemission spectroscopy results. Together, the experimental and theoretical results conclusively show that the 2DEG results from the interface itself, and does not originate from a secondary source such as oxygen vacancies. These heterostructures also exhibit a metal-to-insulator transition as the SrTiO3 layer thickness decreases, which could possibly be used as a "Mott field effect transistor" - the system is very close to a metal-to-insulator transition, and modulating a small fraction of the electron density would lead to switching between the metallic and insulating phases. The mechanism behind this transition is unraveled, and we construct a bulk model of the transition based on the surprising observation that SrTiO3 itself can become a Mott insulator when doped with an extremely high density of electrons.Building on our study of the SrTiO3/GdTiO3 interfaces, we investigate the electronic structure of GdTiO3 in detail - our calculated band gap differs markedly from past experimental values, but is consistent with recent photoluminescence measurements. We find that the presence of small hole polarons leads to a feature in the optical absorption spectrum which was previously interpreted to be the band gap. Since small hole polarons are present in all the rare-earth titanates, not only GdTiO3, the values of the band gaps (also based on optical absorption measurements) across the series will likely have to be revised. Lastly, to understand the formation of small hole polarons in the rare-earth titanates, we study point defects and impurities in GdTiO3. We also investigate how defects may impact the behavior of GdTiO3 in electronic devices

    Digital Atlas of Anatomical Subdivisions and Boundaries of the Rat Hippocampal Region

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    The rat hippocampal region is frequently studied in relation to learning and memory processes and brain diseases. The region is complex, consisting of multiple subdivisions that are challenging to delineate anatomically. Published atlases of the rat brain typically lack the underlying histological criteria necessary to identify boundaries, and textbooks descriptions of the region are often inadequately illustrated and thus difficult to relate to experimental data. An overview of both anatomical features and criteria used to delineate boundaries is required to assign location to experimental material from the hippocampal region. To address this issue, we have developed a web-based atlas application in which images of histological sections are integrated with new and up-to-date criteria for subdividing the rat hippocampus formation, fasciola, and associated parahippocampal regions. The atlas application consists of an interactive image viewer with high-resolution images of an extensive series of sections stained for NeuN, calbindin, and parvalbumin, and an index of structures with detailed descriptions of the criteria used to define the boundaries. Images can be inspected with a graphical overlay of selected subregions. Bi-directional links between images and the index of structures are provided. In summary, we provide a novel content-rich digital atlas resource facilitating identification of morphological features relevant for delineating the anatomical subdivisions of the rat hippocampal region. The atlas application is available at http://www.rbwb.org

    Structural investigation of the bilayer iridate Sr_3Ir_2O_7

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    A complete structural solution of the bilayer iridate compound Sr_3Ir_2O_7 presently remains outstanding. Previously reported structures for this compound vary and all fail to explain weak structural violations observed in neutron scattering measurements as well as the presence of a net ferromagnetic moment in the basal plane. In this paper, we present single crystal neutron diffraction and rotational anisotropy second harmonic generation measurements unveiling a lower, monoclinic symmetry inherent to Sr_3Ir_2O_7. Combined with density functional theory, our measurements identify the correct structural space group as No. 15 (C2/c) and provide clarity regarding the local symmetry of Ir^(4+) cations within this spin-orbit Mott material

    PENGEMBANGAN JOBSHEET TRAINER PLC SEBAGAI SUMBER PEMBELAJARAN PRAKTIKUM OTOMASI INDUSTRI

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    Penelitian ini bertujuan untuk mengembangkan sebuah media pembelajaran sebagai sumber belajar mahasiswa berupa jobsheet praktikum Otomasi Industri. Selain itu, penelitian ini bertujuan untuk mengetahui kelayakan dari jobsheet yang telah dikembangkan serta melihat hasil implementasi jobsheet setelah digunakan oleh para mahasiswa. Penelitian ini dirasa perlu dilakukan untuk membuat sebuah sumber belajar yang layak serta dapat memberikan manfaat lebih khususnya mahasiswa Elektronika Indsutri. Metodologi yang digunakan oleh penulis pada penelitian ini menggunakan penelitian campuran dengan model rancangan campuran sekuensial eksploratori, menggunakan pendekatan penelitian dan pengembangan (Research and Development). Berdasarkan hasil penelitian yang telah dilakukan didapatkan hasil bahwa jobsheet trainer PLC Phoenix Contact ILC 130/131 Starterkit telah dikembangkan sesuai tahapan penelitian dan layak digunakan serta dapat diimplementasikan dalam praktikum Otomasi Industri.---This study aims to develop learning media as a source of students learning in form of practical Industrial Automation jobsheet. Besides, this study aims to prove the feasibility of jobsheet that has been developed and the result of jobsheet implementation by students. This study is considered important to create a decent learning resource and provide benefits, especially for Electronics Industries Students, Department of Electrical Engineering Education, Faculty of Technology and Vocational Skills Education. The methodology used by the authors in this study is mixed research model with exploratory sequences, using a research and development approach (research and development). Based on study results, trainer jobsheet of PLC Phoenix Contact ILC 130/131 Starterkit feasible to be used and can be implemented in practice Industrial Automation
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