5,087 research outputs found

    Chemoanatomical organization of the noradrenergic input from locus coeruleus to the olfactory bulb of the adult rat.

    No full text
    The locus coeruleus contains noradrenergic neurons which project widely throughout the CNS. A major target of locus coeruleus projections in the rat is the olfactory bulb (Shipley et al.: Brain Res. 329:294–299, '85) but the organization of the projections within the bulb has not been systematically examined. In this study, the laminar distribution and densities of locus coeruleus-noradrenergic fibers in the main and accessory olfactory bulbs were determined with anterograde tracing and immunocytochemical techniques. Following iontophoretic injections of 1% wheat germ agglutinin-horseradish peroxidase into the locus coeruleus, the densest anterograde label in the accessory olfactory bulb was observed in the external plexiform layer, granule cell layer, and especially in the internal part of the mitral cell layer. Virtually no label was observed in the glomerular layer. In the main olfactory bulb, labelled axons were observed in the granule cell layer, in the internal and external plexiform layers, occasionally in the mitral cell layer, and least often in the glomerular layer. Noradrenergic fibers in the olfactory bulb were identified by using immunocytochemistry with an antibody to dopamine-β-hydroxylase. Laminar patterns and densities of noradrenergic innervation were determined with quantitative image analysis. In the accessory olfactory bulb, the densest innervation was in the innermost portion of the mitral cell layer followed by the granule cell layer, the superficial part of the mitral cell layer, and the external plexiform layer. The density of fibers in the glomerular layer was least. The laminar pattern of noradrenergic fiber distribution in the main olfactory bulb was similar to that in accessory olfactory bulb. The present studies demonstrate that locus coeruleus-noradrenergic fibers terminate preferentially in the internal plexiform, granule cell, and external plexiform layers. This suggests that the major influence of the locus coeruleus input to both the main and accessory the olfactory bulbs is on the predominant neuronal element in those layers, the granule cells. Additional studies are needed to resolve how this input influences specific olfactory bulb circuits

    Final State Interactions in Hadronic D decays

    Full text link
    We show that the large corrections due to final state interactions (FSI) in the D^+\to \pi^-\pi^+\pi^+, D^+_s\to \pi^-\pi^+\pi^+, and D^+\to K^-\pi^+\pi^+ decays can be accounted for by invoking scattering amplitudes in agreement with those derived from phase shifts studies. In this way, broad/overlapping resonances in S-waves are properly treated and the phase motions of the transition amplitudes are driven by the corresponding scattering matrix elements determined in many other experiments. This is an important step forward in resolving the puzzle of the FSI in these decays. We also discuss why the \sigma and \kappa resonances, hardly visible in scattering experiments, are much more prominent and clearly visible in these decays without destroying the agreement with the experimental \pi\pi and K\pi low energy S-wave phase shifts.Comment: 22 pages, 6 figures, 5 tables. Minor changes. We extend the discusion when quoting a reference and we include a new one. Some typos are fixe

    Strong Decays of Strange Quarkonia

    Get PDF
    In this paper we evaluate strong decay amplitudes and partial widths of strange mesons (strangeonia and kaonia) in the 3P0 decay model. We give numerical results for all energetically allowed open-flavor two-body decay modes of all nsbar and ssbar strange mesons in the 1S, 2S, 3S, 1P, 2P, 1D and 1F multiplets, comprising strong decays of a total of 43 resonances into 525 two-body modes, with 891 numerically evaluated amplitudes. This set of resonances includes all strange qqbar states with allowed strong decays expected in the quark model up to ca. 2.2 GeV. We use standard nonrelativistic quark model SHO wavefunctions to evaluate these amplitudes, and quote numerical results for all amplitudes present in each decay mode. We also discuss the status of the associated experimental candidates, and note which states and decay modes would be especially interesting for future experimental study at hadronic, e+e- and photoproduction facilities. These results should also be useful in distinguishing conventional quark model mesons from exotica such as glueballs and hybrids through their strong decays.Comment: 69 pages, 5 figures, 39 table

    Experimental results for nulling the effective thermal expansion coefficient of fused silica fibres under a static stress

    Get PDF
    We have experimentally demonstrated that the effective thermal expansion coefficient of a fused silica fibre can be nulled by placing the fibre under a particular level of stress. Our technique involves heating the fibre and measuring how the fibre length changes with temperature as the stress on the fibre was systematically varied. This nulling of the effective thermal expansion coefficient should allow for the complete elimination of thermoelastic noise and is essential for allowing second generation gravitational wave detectors to reach their target sensitivity. To our knowledge this is the first time that the cancelation of the thermal expansion coefficient with stress has been experimentally observed

    Spin-Parity Analysis of the Centrally produced KsKs system at 800 GeV

    Get PDF
    Results are presented of the spin-parity analysis on a sample of centrally produced mesons in the reaction (p p -> p_{slow} K_s K_s p_{fast}) with 800 GeV protons on liquid hydrogen. The spin-parity analysis in the mass region between threshold and 1.58 GeV/c^2 shows that the (K_s K_s) system is produced mainly in S-wave. The f_0(1500) is clearly observed in this region. Above 1.58 GeV/c^2 two solutions are possible, one with mainly S-wave and another with mainly D-wave. This ambiguity prevents a unique determination of the spin of the f_J(1710) meson.Comment: 6 pages, including 6 figures. LaTex, uses 'espcrc2.sty'. To appear in LEAP'96 proceeding

    Small optic suspensions for Advanced LIGO input optics and other precision optical experiments

    Get PDF
    We report on the design and performance of small optic suspensions developed to suppress seismic motion of out-of-cavity optics in the Input Optics subsystem of the Advanced LIGO interferometric gravitational wave detector. These compact single stage suspensions provide isolation in all six degrees of freedom of the optic, local sensing and actuation in three of them, and passive damping for the other three

    The Electromagnetic Mass Differences of Pions and Kaons

    Get PDF
    We use the Cottingham method to calculate the pion and kaon electromagnetic mass differences with as few model dependent inputs as possible. The constraints of chiral symmetry at low energy, QCD at high energy and experimental data in between are used in the dispersion relation. We find excellent agreement with experiment for the pion mass difference. The kaon mass difference exhibits a strong violation of the lowest order prediction of Dashen's theorem, in qualitative agreement with several other recent calculations.Comment: 40 pages, Latex, needs axodraw. and psfig. macros, 4 figure

    Bifurcations of periodic orbits with spatio-temporal symmetries

    Get PDF
    Motivated by recent analytical and numerical work on two- and three-dimensional convection with imposed spatial periodicity, we analyse three examples of bifurcations from a continuous group orbit of spatio-temporally symmetric periodic solutions of partial differential equations. Our approach is based on centre manifold reduction for maps, and is in the spirit of earlier work by Iooss (1986) on bifurcations of group orbits of spatially symmetric equilibria. Two examples, two-dimensional pulsating waves (PW) and three-dimensional alternating pulsating waves (APW), have discrete spatio-temporal symmetries characterized by the cyclic groups Z_n, n=2 (PW) and n=4 (APW). These symmetries force the Poincare' return map M to be the nth iterate of a map G: M=G^n. The group orbits of PW and APW are generated by translations in the horizontal directions and correspond to a circle and a two-torus, respectively. An instability of pulsating waves can lead to solutions that drift along the group orbit, while bifurcations with Floquet multiplier +1 of alternating pulsating waves do not lead to drifting solutions. The third example we consider, alternating rolls, has the spatio-temporal symmetry of alternating pulsating waves as well as being invariant under reflections in two vertical planes. This leads to the possibility of a doubling of the marginal Floquet multiplier and of bifurcation to two distinct types of drifting solutions. We conclude by proposing a systematic way of analysing steady-state bifurcations of periodic orbits with discrete spatio-temporal symmetries, based on applying the equivariant branching lemma to the irreducible representations of the spatio-temporal symmetry group of the periodic orbit, and on the normal form results of Lamb (1996). This general approach is relevant to other pattern formation problems, and contributes to our understanding of the transition from ordered to disordered behaviour in pattern-forming systems

    Towards modelling language innovation acceptance in online social networks

    Get PDF
    Language change and innovation is constant in online and offline communication, and has led to new words entering people’s lexicon and even entering modern day dictionaries, with recent additions of ‘e-cig’ and ‘vape’. However the manual work required to identify these ‘innovations’ is both time consuming and subjective. In this work we demonstrate how such innovations in language can be identified across two different OSN’s (Online Social Networks) through the operationalisation of known language acceptance models that incorporate relatively simplistic statistical tests. From grounding our work in language theory, we identified three statistical tests that can be applied, variation in; frequency, form and meaning; each showing different success rates across the two networks (Geo-bound Twitter sample and a sample of Reddit). These tests were also applied to different community levels within the two networks allow- ing for different innovations to be identified across different community structures over the two networks, for instance: identifying regional variation across Twitter, and variation across groupings of Subreddits, where identified example in- novations included ‘casualidad’ and ‘cym’
    corecore