50 research outputs found
Geniculo-Cortical Projection Diversity Revealed within the Mouse Visual Thalamus
This is the final version of the article. It was first available from PLOS via http://dx.doi.org/10.1371/journal.pone.0144846All dLGN cell co-ordinates, V1 injection sites, dLGN boundary coordinates, experimental protocols and analysis scripts are available for download from figshare at https://figshare.com/s/36c6d937b1844eec80a1.The mouse dorsal lateral geniculate nucleus (dLGN) is an intermediary between retina and primary visual cortex (V1). Recent investigations are beginning to reveal regional complexity in mouse dLGN. Using local injections of retrograde tracers into V1 of adult and neonatal mice, we examined the developing organisation of geniculate projection columns: the population of dLGN-V1 projection neurons that converge in cortex. Serial sectioning of the dLGN enabled the distribution of labelled projection neurons to be reconstructed and collated within a common standardised space. This enabled us to determine: the organisation of cells within the dLGN-V1 projection columns; their internal organisation (topology); and their order relative to V1 (topography). Here, we report parameters of projection columns that are highly variable in young animals and refined in the adult, exhibiting profiles consistent with shell and core zones of the dLGN. Additionally, such profiles are disrupted in adult animals with reduced correlated spontaneous activity during development. Assessing the variability between groups with partial least squares regression suggests that 4?6 cryptic lamina may exist along the length of the projection column. Our findings further spotlight the diversity of the mouse dLGN?an increasingly important model system for understanding the pre-cortical organisation and processing of visual information. Furthermore, our approach of using standardised spaces and pooling information across many animals will enhance future functional studies of the dLGN.Funding was provided by a Wellcome Trust grant jointly awarded to IDT and SJE (083205, www.wellcome.ac.uk), and by MRC PhD Studentships awarded to MNL and ACH (http://www.mrc.ac.uk/)
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ICH antenna development on the ORNL RF Test Facility
A compact resonant loop antenna is installed on the ORNL Radio Frequency Test Facility (RFTF). Facility characteristics include a steady-state magnetic field of {approx} 0.5 T at the antenna, microwave-generated plasmas with n{sub e} {approx} 10{sup 12} cm{sup {minus}3} and T{sub e} {approx} 8 eV, and 100 kW of 25-MHz rf power. The antenna is tunable from {approximately}22--75 MHz, is designed to handle {ge}1 MW of rf power, and can be moved 5 cm with respect to the port flange. Antenna characteristics reported and discussed include the effect of magnetic field on rf voltage breakdown at the capacitor, the effects of magnetic field and plasma on rf voltage breakdown between the radiating element and the Faraday shield, the effects of graphite on Faraday shield losses, and the efficiency of coupling to the plasma. 2 refs., 4 figs
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Characterization of actinide physics specimens for the US/UK joint experiment in the Dounreay Prototype Fast Reactor
The United States and the United Kingdom are engaged in a joint research program in which samples of the higher actinides are irradiated in the Dounreay Prototype Fast Reactor in Scotland. The purpose of the porogram is (1) to study the materials behavior of selected higher actinide fuels and (2) to determine the integral cross sections of a wide variety of the higher actinide isotopes. Samples of the actinides are incorporated in fuel pins inserted in the core. For the fuel study, the actinides selected are /sup 241/Am and /sup 244/Cm in the form of Am/sub 2/O/sub 3/, Cm/sub 2/O/sub 3/, and Am/sub 6/Cm(RE)/sub 7/O/sub 21/, where (RE) represents a mixture of lanthanides. For the cross-section determinations, the samples are milligram quantities of actinide oxides of /sup 248/Cm, /sup 246/Cm, /sup 244/Cm, /sup 243/Cm, /sup 243/Am, /sup 241/Am, /sup 244/Pu, /sup 242/Pu, /sup 241/Pu, /sup 240/Pu, /sup 239/Pu, /sup 238/Pu, /sup 237/Np, /sup 238/U, /sup 236/U, /sup 235/U, /sup 234/U, /sup 233/U, /sup 232/Th, /sup 230/Th, and /sup 231/Pa encapsulated in vanadium. Coincident with the irradiations, neutron flux and energy spectral measurements are made with vanadium-encapsulated dosimeter materials located within the same fuel pins
Protecting an estuary from floods: A policy analysis of the Oosterschelde. Vol 2: Assessment of security from flooding
The second volume in a series of reports describing the methodology and results of a joint research venture between RAND and the Netherlands Rijkswaterstaat. The POLANO project was founded to help the Dutch government analyze the different alternatives (open, closed, and storm-surge barrier cases) for protecting the Oosterschelde region from North Sea floods. Volume II describes the methodology developed to estimate the likelihood and severity of flood damage to people, property, and land under each of the alternatives. These are subjected to many simulated threats expressed in terms of storm water levels. The methodology's damage estimates compared favorably with the actual damage observed in a severe 1953 storm. Also assessed is the reliability of the storm-surge barrier. The report demonstrates how security varies, in both the long-run and construction periods, with changes in the alternatives and assumptions.Polan