WorldWideScience

Sample records for thin keplerian discs

  1. Secular Instabilities of Keplerian Stellar Discs

    Science.gov (United States)

    Kaur, Karamveer; Kazandjian, Mher; Sridhar, S.; Touma, Jihad

    2018-02-01

    We present idealized models of a razor-thin, axisymmetric, Keplerian stellar disc around a massive black hole, and study non-axisymmetric secular instabilities in the absence of either counter-rotation or loss cones. These discs are prograde mono-energetic waterbags, whose phase space distribution functions are constant for orbits within a range of eccentricities (e) and zero outside this range. The linear normal modes of waterbags are composed of sinusoidal disturbances of the edges of distribution function in phase space. Waterbags which include circular orbits (polarcaps) have one stable linear normal mode for each azimuthal wavenumber m. The m = 1 mode always has positive pattern speed and, for polarcaps consisting of orbits with e normal modes for each m, which can be stable or unstable. We derive analytical expressions for the instability condition, pattern speeds, growth rates and normal mode structure. Narrow bands are unstable to modes with a wide range in m. Numerical simulations confirm linear theory and follow the non-linear evolution of instabilities. Long-time integration suggests that instabilities of different m grow, interact non-linearly and relax collisionlessly to a coarse-grained equilibrium with a wide range of eccentricities.

  2. Excitation of nonaxisymmetric perturbations by the axisymmetric explosive magnetorotational instability in Keplerian discs

    Science.gov (United States)

    Shtemler, Yu.; Mond, M.; Liverts, E.

    2018-02-01

    The excitation of nonaxisymmetric quasi-resonant triads by clustering around a dominant axisymmetric explosively unstable magnetorotational instability (MRI) in Keplerian discs is investigated. Clustering, namely, the mutual interactions of a large number of quasi-resonant triads that are connected by a single dominant explosively unstable axisymmetric triad, is invoked in order to provide a viable mechanism for the stabilization of the explosive nature of the latter. The results, however, are of wider scope as the proposed clustering scenario also provides a strong mechanism for the excitation of high-amplitude nonaxisymmetric perturbations. The latter play a major role in the nonlinear evolution of the MRI on the route to fully developed turbulence.

  3. Radiation-pressure-driven sub-Keplerian rotation of the disc around the AGB star L2 Pup

    Science.gov (United States)

    Haworth, Thomas J.; Booth, Richard A.; Homan, Ward; Decin, Leen; Clarke, Cathie J.; Mohanty, Subhanjoy

    2018-01-01

    We study the sub-Keplerian rotation and dust content of the circumstellar material around the asymptotic giant branch (AGB) star L2 Puppis. We find that the thermal pressure gradient alone cannot explain the observed rotation profile. We find that there is a family of possible dust populations for which radiation pressure can drive the observed sub-Keplerian rotation. This set of solutions is further constrained by the spectral energy distribution (SED) of the system, and we find that a dust-to-gas mass ratio of ∼10-3 and a maximum grain size that decreases radially outwards can satisfy both the rotation curve and SED. These dust populations are dynamically tightly coupled to the gas azimuthally. However, grains larger than ∼ 0.5 μm are driven outwards radially by radiation pressure at velocities ∼5 km s-1, which implies a dust replenishment rate of ∼3 × 10-9 M⊙ yr-1. This replenishment rate is consistent with observational estimates to within uncertainties. Coupling between the radial motion of the dust and gas is weak and hence the gas does not share in this rapid outward motion. Overall, we conclude that radiation pressure is a capable and necessary mechanism to explain the observed rotation profile of L2 Pup, and offers other additional constraints on the dust properties.

  4. Line-driven ablation of circumstellar discs - I. Optically thin decretion discs of classical Oe/Be stars.

    Science.gov (United States)

    Kee, Nathaniel Dylan; Owocki, Stanley; Sundqvist, J O

    2016-05-21

    The extreme luminosities of massive, hot OB stars drive strong stellar winds through line-scattering of the star's UV continuum radiation. For OB stars with an orbiting circumstellar disc, we explore here the effect of such line-scattering in driving an ablation of material from the disc's surface layers, with initial focus on the marginally optically thin decretion discs of classical Oe and Be stars. For this we apply a multidimensional radiation-hydrodynamics code that assumes simple optically thin ray tracing for the stellar continuum, but uses a multiray Sobolev treatment of the line transfer; this fully accounts for the efficient driving by non-radial rays, due to desaturation of line-absorption by velocity gradients associated with the Keplerian shear in the disc. Results show a dense, intermediate-speed surface ablation, consistent with the strong, blueshifted absorption of UV wind lines seen in Be shell stars that are observed from near the disc plane. A key overall result is that, after an initial adjustment to the introduction of the disc, the asymptotic disc destruction rate is typically just an order-unity factor times the stellar wind mass-loss rate. For optically thin Be discs, this leads to a disc destruction time of order months to years, consistent with observationally inferred disc decay times. The much stronger radiative forces of O stars reduce this time to order days, making it more difficult for decretion processes to sustain a disc in earlier spectral types, and so providing a natural explanation for the relative rarity of Oe stars in the Galaxy. Moreover, the decrease in line-driving at lower metallicity implies both a reduction in the winds that help spin-down stars from near-critical rotation, and a reduction in the ablation of any decretion disc; together these provide a natural explanation for the higher fraction of classical Be stars, as well as the presence of Oe stars, in the lower metallicity Magellanic Clouds. We conclude with a

  5. Osculating Keplerian Elements for Highly Non-Keplerian Orbits

    Science.gov (United States)

    2017-03-27

    elements to non-Keplerian orbit geometry have been generated. These mappings have been derived in closed, analytical form. A sensitivity analysis has been...AFRL-AFOSR-UK-TR-2017-0026 Osculating Keplerian Elements for Highly Non-Keplerian Orbits Colin McInnes THE UNIVERSITY OF GLASGOW Final Report 03/27...of information if it does not display a currently valid OMB control number. UNIVERSITY OF GLASGOW SCHOOL OF ENGINEERING Osculating Keplerian

  6. Schrödinger evolution of self-gravitating discs

    Science.gov (United States)

    Batygin, Konstantin

    2018-04-01

    An understanding of the long-term evolution of self-gravitating discs ranks among the classic outstanding problems of astrophysics. In this work, we show that the secular inclination dynamics of a geometrically thin quasi-Keplerian disc, with a surface density profile that scales as the inverse square-root of the orbital radius, are described by the time-dependent Schrödinger equation. Within the context of this formalism, nodal bending waves correspond to the eigenmodes of a quasi-particle's wavefunction, confined in an infinite square well with boundaries given by the radial extent of the disc. We further show that external secular perturbations upon self-gravitating discs exhibit a mathematical similarity to quantum scattering theory. Employing this framework, we derive an analytic criterion for the gravitational rigidity of a nearly-Keplerian disc under external perturbations. Applications of the theory to circumstellar discs and Galactic nuclei are discussed.

  7. The Gaia-ESO Survey: the Galactic thick to thin disc transition

    NARCIS (Netherlands)

    Recio-Blanco, A.; de Laverny, P.; Kordopatis, G.; Helmi, A.; Hill, V.; Gilmore, G.; Wyse, R.; Adibekyan, V.; Randich, S.; Asplund, M.; Feltzing, S.; Jeffries, R.; Micela, G.; Vallenari, A.; Alfaro, E.; Allende Prieto, C.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Koposov, S. E.; Korn, A.; Lanzafame, A.; Pancino, E.; Smiljanic, R.; Jackson, R.; Lewis, J.; Magrini, L.; Morbidelli, L.; Prisinzano, L.; Sacco, G.; Worley, C. C.; Hourihane, A.; Bergemann, M.; Costado, M. T.; Heiter, U.; Joffre, P.; Lardo, C.; Lind, K.; Maiorca, E.

    Aims: The nature of the thick disc and its relation to the thin disc is presently an important subject of debate. In fact, the structural and chemo-dynamical transition between disc populations can be used as a test of the proposed models of Galactic disc formation and evolution. Methods: We used

  8. Thin viscoelastic disc subjected to radial non-stationary loading

    Directory of Open Access Journals (Sweden)

    Adámek V.

    2010-07-01

    Full Text Available The investigation of non-stationary wave phenomena in isotropic viscoelastic solids using analytical approaches is the aim of this paper. Concretely, the problem of a thin homogeneous disc subjected to radial pressure load nonzero on the part of its rim is solved. The external excitation is described by the Heaviside function in time, so the nonstationary state of stress is induced in the disc. Dissipative material behaviour of solid studied is represented by the discrete material model of standard linear viscoelastic solid in the Zener configuration. After the derivation of motion equations final form, the method of integral transforms in combination with the Fourier method is used for finding the problem solution. The solving process results in the derivation of integral transforms of radial and circumferential displacement components. Finally, the type of derived functions singularities and possible methods for their inverse Laplace transform are mentioned.

  9. Evaluation of Retinal Nerve Fiber Layer Thinning in Myopic Glaucoma: Impact of Optic Disc Morphology.

    Science.gov (United States)

    Na, Kyeong Ik; Lee, Won June; Kim, Young Kook; Park, Ki Ho; Jeoung, Jin Wook

    2017-12-01

    The purpose of this study was to investigate the role of optic disc torsion on the rate of progressive retinal nerve fiber layer (RNFL) thinning in patients with myopic open-angle glaucoma. We included 102 patients with myopic open-angle glaucoma accompanied by glaucomatous damage confined to a single hemiretina who were followed up over a 5-year period. We divided the subjects into three groups according to the presence or absence of optic disc torsion and the correspondence between the direction of optic disc torsion and the location of glaucomatous damage: torsion with reverse correspondence group (eyes showing inferior optic disc torsion with glaucomatous damage in the superior quadrant or eyes showing superior torsion with damage in the inferior quadrant), no torsion group, and torsion with correspondence group (eyes showing inferior optic disc torsion with glaucomatous damage in the inferior quadrant or eyes showing superior torsion with damage in the superior quadrant). Changes in the peripapillary RNFL thickness (pRNFLT), evaluated using linear mixed model analysis, were compared among the three groups to determine the relationship between optic disc torsion and pRNFLT changes. Among the total of 102 subjects, 13 eyes (12.7%) exhibited optic disc torsion with reverse correspondence, 59 (57.8%) did not exhibit optic disc torsion, and 30 (29.4%) exhibited optic disc torsion with correspondence. pRNFL thinning in the quadrant with glaucomatous damage was significantly faster in the torsion with correspondence group (-1.66 μm/y) than those in the no torsion (-1.14 μm/y; P = 0.032) and torsion with reverse correspondence (-0.50 μm/y; P optic disc torsion-glaucomatous damage correspondence is an important prognostic factor for patients with myopic open-angle glaucoma.

  10. The Gaia-ESO Survey: the Galactic thick to thin disc transition

    Science.gov (United States)

    Recio-Blanco, A.; de Laverny, P.; Kordopatis, G.; Helmi, A.; Hill, V.; Gilmore, G.; Wyse, R.; Adibekyan, V.; Randich, S.; Asplund, M.; Feltzing, S.; Jeffries, R.; Micela, G.; Vallenari, A.; Alfaro, E.; Allende Prieto, C.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Koposov, S. E.; Korn, A.; Lanzafame, A.; Pancino, E.; Smiljanic, R.; Jackson, R.; Lewis, J.; Magrini, L.; Morbidelli, L.; Prisinzano, L.; Sacco, G.; Worley, C. C.; Hourihane, A.; Bergemann, M.; Costado, M. T.; Heiter, U.; Joffre, P.; Lardo, C.; Lind, K.; Maiorca, E.

    2014-07-01

    Aims: The nature of the thick disc and its relation to the thin disc is presently an important subject of debate. In fact, the structural and chemo-dynamical transition between disc populations can be used as a test of the proposed models of Galactic disc formation and evolution. Methods: We used the atmospheric parameters, [α/Fe] abundances, and radial velocities, which were determined from the Gaia-ESO Survey GIRAFFE spectra of FGK-type stars (first nine months of observations) to provide a chemo-kinematical characterisation of the disc stellar populations. We focussed on a subsample of 1016 stars with high-quality parameters, covering the volume | Z | contamination by thin disc stars suggests a gradient up to 64 ± 9 km s-1 dex-1. The distributions of azimuthal velocity, vertical velocity, and orbital parameters are also analysed for the chemically separated samples. Concerning the gradients with galactocentric radius, we find, for the thin disc, a flat behaviour of the azimuthal velocity, a metallicity gradient equal to -0.058 ± 0.008 dex kpc-1 and a very small positive [α/Fe] gradient. For the thick disc, flat gradients in [M/H] and [α/Fe] are derived. Conclusions: Our chemo-kinematical analysis suggests a picture where the thick disc seems to have experienced a settling process, during which its rotation increased progressively and, possibly, the azimuthal velocity dispersion decreased. At [M/H] ≈ -0.25 dex and [α/Fe]≈ 0.1 dex, the mean characteristics of the thick disc in vertical distance to the Galactic plane, rotation, rotational dispersion, and stellar orbits' eccentricity agree with that of the thin disc stars of the same metallicity, suggesting a possible connection between these two populations at a certain epoch of the disc evolution. Finally, the results presented here, based only on the first months of the Gaia ESO Survey observations, confirm how crucial large high-resolution spectroscopic surveys outside the solar neighbourhood are today

  11. The structural evolution of galaxies with both thin and thick discs

    Science.gov (United States)

    Aumer, Michael; Binney, James

    2017-09-01

    We perform controlled N-body simulations of disc galaxies growing within live dark matter (DM) haloes to present-day galaxies that contain both thin and thick discs. We consider two types of models: (a) thick-disc initial conditions to which stars on near-circular orbits are continuously added over ˜10 Gyr, and (b) models in which the birth velocity dispersion of stars decreases continuously over the same time-scale. We show that both schemes produce double-exponential vertical profiles similar to that of the Milky Way (MW). We indicate how the spatial age structure of galaxies can be used to discriminate between scenarios. We show that the presence of a thick disc significantly alters and delays bar formation and thus makes possible models with a realistic bar and a high baryon-to-DM mass ratio in the central regions, as required by microlensing constraints. We examine how the radial mass distribution in stars and DM is affected by disc growth and non-axisymmetries. We discuss how bar buckling shapes the vertical age distribution of thin- and thick-disc stars in the bar region. The extent to which the combination of observationally motivated inside-out growth histories and cosmologically motivated dark halo properties leads to the spontaneous formation of non-axisymmetries that steer the models towards present-day MW-like galaxies is noteworthy.

  12. Interactive Visualization of a Thin Disc around a Schwarzschild Black Hole

    Science.gov (United States)

    Muller, Thomas; Frauendiener, Jorg

    2012-01-01

    In a first course in general relativity, the Schwarzschild spacetime is the most discussed analytic solution to Einstein's field equations. Unfortunately, there is rarely enough time to study the optical consequences of the bending of light for some advanced examples. In this paper, we present how the visual appearance of a thin disc around a…

  13. The absence of a thin disc in M81

    Science.gov (United States)

    Young, A. J.; McHardy, I.; Emmanoulopoulos, D.; Connolly, S.

    2018-03-01

    We present the results of simultaneous Suzaku and NuSTAR observations of the nearest Low-Luminosity Active Galactic Nucleus (LLAGN), M81*. The spectrum is well described by a cut-off power law plus narrow emission lines from Fe Kα, Fe XXV and Fe XXVI. There is no evidence of Compton reflection from an optically thick disc, and we obtain the strongest constraint on the reflection fraction in M81* to date, with a best-fit value of R = 0.0 with an upper limit of R limit.

  14. Reduction of some perturbed Keplerian problems

    International Nuclear Information System (INIS)

    Inarrea, Manuel; Lanchares, Victor; Palacian, Jesus F.; Pascual, Ana I.; Salas, J. Pablo; Yanguas, Patricia

    2006-01-01

    Perturbed Hamiltonian Keplerian systems enjoying some discrete and continuous symmetries can be brought to a one degree of freedom system containing the main qualitative features of the original one. This reduced system is defined in a compact set of the plane where the qualitative dynamics can be studied in a systematic way

  15. Optical coherence tomography detection of characteristic retinal nerve fiber layer thinning in nasal hypoplasia of the optic disc.

    Science.gov (United States)

    Haruta, M; Kodama, R; Yamakawa, R

    2017-12-01

    PurposeTo determine the clinical usefulness of optical coherence tomography (OCT) for detecting thinning of the retinal nerve fiber layer (RNFL) in eyes with nasal hypoplasia of the optic discs (NHOD).Patients and methodsThe medical records of five patients (eight eyes) with NHOD were reviewed. The ratio of the disc-macula distance to the disc diameter (DM/DD) and the disc ovality ratio of the minimal to maximal DD were assessed using fundus photographs. The RNFL thicknesses of the temporal, superior, nasal, and inferior quadrants were evaluated using OCT quadrant maps.ResultsAll eight eyes had temporal visual field defects that respected the vertical meridians that needed to be differentiated from those related to chiasmal compression. The mean DM/DD ratio was 3.1 and the mean disc ovality ratio was 0.81. The mean RNFL thicknesses of the temporal, superior, nasal, and inferior quadrants were 90.3, 103.1, 34.8, and 112.8 microns, respectively.ConclusionSmall optic discs and tilted discs might be associated with NHOD. Measurement of the RNFL thickness around the optic disc using OCT scans clearly visualized the characteristic RNFL thinning of the nasal quadrants corresponding to the temporal sector visual field defects in eyes with NHOD. OCT confirmed the presence of NHOD and might differentiate eyes with NHOD from those with chiasmal compression.

  16. Optically thin core accretion: how planets get their gas in nearly gas-free discs

    Science.gov (United States)

    Lee, Eve J.; Chiang, Eugene; Ferguson, Jason W.

    2018-05-01

    Models of core accretion assume that in the radiative zones of accreting gas envelopes, radiation diffuses. But super-Earths/sub-Neptunes (1-4 R⊕, 2-20 M⊕) point to formation conditions that are optically thin: their modest gas masses are accreted from short-lived and gas-poor nebulae reminiscent of the transparent cavities of transitional discs. Planetary atmospheres born in such environments can be optically thin to both incident starlight and internally generated thermal radiation. We construct time-dependent models of such atmospheres, showing that super-Earths/sub-Neptunes can accrete their ˜1 per cent-by-mass gas envelopes, and super-puffs/sub-Saturns their ˜20 per cent-by-mass envelopes, over a wide range of nebular depletion histories requiring no fine tuning. Although nascent atmospheres can exhibit stratospheric temperature inversions affected by atomic Fe and various oxides that absorb strongly at visible wavelengths, the rate of gas accretion remains controlled by the radiative-convective boundary (rcb) at much greater pressures. For dusty envelopes, the temperature at the rcb Trcb ≃ 2500 K is still set by H2 dissociation; for dust-depleted envelopes, Trcb tracks the temperature of the visible or thermal photosphere, whichever is deeper, out to at least ˜5 au. The rate of envelope growth remains largely unchanged between the old radiative diffusion models and the new optically thin models, reinforcing how robustly super-Earths form as part of the endgame chapter in disc evolution.

  17. Schwarzschild black hole encircled by a rotating thin disc: Properties of perturbative solution

    Science.gov (United States)

    Kotlařík, P.; Semerák, O.; Čížek, P.

    2018-04-01

    Will [Astrophys. J. 191, 521 (1974), 10.1086/152992] solved the perturbation of a Schwarzschild black hole due to a slowly rotating light concentric thin ring, using Green's functions expressed as infinite-sum expansions in multipoles and in the small mass and rotational parameters. In a previous paper [P. Čížek and O. Semerák, Astrophys. J. Suppl. Ser. 232, 14 (2017), 10.3847/1538-4365/aa876b], we expressed the Green functions in closed form containing elliptic integrals, leaving just summation over the mass expansion. Such a form is more practical for numerical evaluation, but mainly for generalizing the problem to extended sources where the Green functions have to be integrated over the source. We exemplified the method by computing explicitly the first-order perturbation due to a slowly rotating thin disc lying between two finite radii. After finding basic parameters of the system—mass and angular momentum of the black hole and of the disc—we now add further properties, namely those which reveal how the disc gravity influences geometry of the black-hole horizon and those of circular equatorial geodesics (specifically, radii of the photon, marginally bound and marginally stable orbits). We also realize that, in the linear order, no ergosphere occurs and the central singularity remains pointlike, and check the implications of natural physical requirements (energy conditions and subluminal restriction on orbital speed) for the single-stream as well as counter-rotating double-stream interpretations of the disc.

  18. The Gaia-ESO Survey: Lithium enrichment histories of the Galactic thick and thin disc

    Science.gov (United States)

    Fu, X.; Romano, D.; Bragaglia, A.; Mucciarelli, A.; Lind, K.; Delgado Mena, E.; Sousa, S. G.; Randich, S.; Bressan, A.; Sbordone, L.; Martell, S.; Korn, A. J.; Abia, C.; Smiljanic, R.; Jofré, P.; Pancino, E.; Tautvaišienė, G.; Tang, B.; Magrini, L.; Lanzafame, A. C.; Carraro, G.; Bensby, T.; Damiani, F.; Alfaro, E. J.; Flaccomio, E.; Morbidelli, L.; Zaggia, S.; Lardo, C.; Monaco, L.; Frasca, A.; Donati, P.; Drazdauskas, A.; Chorniy, Y.; Bayo, A.; Kordopatis, G.

    2018-02-01

    Lithium abundance in most of the warm metal-poor main sequence stars shows a constarnt plateau (A(Li) 2.2 dex) and then the upper envelope of the lithium vs. metallicity distribution increases as we approach solar metallicity. Meteorites, which carry information about the chemical composition of the interstellar medium (ISM) at the solar system formation time, show a lithium abundance A(Li) 3.26 dex. This pattern reflects the Li enrichment history of the ISM during the Galaxy lifetime. After the initial Li production in big bang nucleosynthesis, the sources of the enrichment include asymptotic giant branch (AGB) stars, low-mass red giants, novae, type II supernovae, and Galactic cosmic rays. The total amount of enriched Li is sensitive to the relative contribution of these sources. Thus different Li enrichment histories are expected in the Galactic thick and thin disc. We investigate the main sequence stars observed with UVES in Gaia-ESO Survey iDR4 catalogue and find a Li-anticorrelation independent of [Fe/H], Teff, and log(g). Since in stellar evolution different α enhancements at the same metallicity do not lead to a measurable Li abundance change, the anticorrelation indicates that more Li is produced during the Galactic thin disc phase than during the Galactic thick disc phase. We also find a correlation between the abundance of Li and s-process elements Ba and Y, and they both decrease above the solar metallicity, which can be explained in the framework of the adopted Galactic chemical evolution models. The full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A38

  19. kW-class picosecond thin-disc prepulse laser Perla for efficient EUV generation

    Czech Academy of Sciences Publication Activity Database

    Endo, Akira; Smrž, Martin; Mužík, Jiří; Novák, Ondřej; Chyla, Michal; Mocek, Tomáš

    2017-01-01

    Roč. 16, č. 4 (2017), s. 1-6, č. článku 041011. ISSN 1932-5150 R&D Projects: GA MŠk LO1602; GA ČR GA16-12960S; GA MŠk LM2015086 EU Projects: European Commission(XE) 739573 - HiLASE CoE Grant - others:OP VVV - HiLASE-CoE(XE) CZ.02.1.01/0.0/0.0/15_006/0000674 Institutional support: RVO:68378271 Keywords : EUV source * laser produced plasma * FEL * prepulse * thin-disc laser Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 1.350, year: 2016

  20. Metrics in Keplerian orbits quotient spaces

    Science.gov (United States)

    Milanov, Danila V.

    2018-03-01

    Quotient spaces of Keplerian orbits are important instruments for the modelling of orbit samples of celestial bodies on a large time span. We suppose that variations of the orbital eccentricities, inclinations and semi-major axes remain sufficiently small, while arbitrary perturbations are allowed for the arguments of pericentres or longitudes of the nodes, or both. The distance between orbits or their images in quotient spaces serves as a numerical criterion for such problems of Celestial Mechanics as search for common origin of meteoroid streams, comets, and asteroids, asteroid families identification, and others. In this paper, we consider quotient sets of the non-rectilinear Keplerian orbits space H. Their elements are identified irrespective of the values of pericentre arguments or node longitudes. We prove that distance functions on the quotient sets, introduced in Kholshevnikov et al. (Mon Not R Astron Soc 462:2275-2283, 2016), satisfy metric space axioms and discuss theoretical and practical importance of this result. Isometric embeddings of the quotient spaces into R^n, and a space of compact subsets of H with Hausdorff metric are constructed. The Euclidean representations of the orbits spaces find its applications in a problem of orbit averaging and computational algorithms specific to Euclidean space. We also explore completions of H and its quotient spaces with respect to corresponding metrics and establish a relation between elements of the extended spaces and rectilinear trajectories. Distance between an orbit and subsets of elliptic and hyperbolic orbits is calculated. This quantity provides an upper bound for the metric value in a problem of close orbits identification. Finally the invariance of the equivalence relations in H under coordinates change is discussed.

  1. Fabrication and characteristics of thin disc piezoelectric transformers based on piezoelectric buzzers with gap circles.

    Science.gov (United States)

    Chang, Kuo-Tsai; Lee, Chun-Wei

    2008-04-01

    This paper investigates design, fabrication and test of thin disc piezoelectric transformers (PTs) based on piezoelectric buzzers with gap circles at different diameters of the gap circles. The performance test is focused on characteristics of voltage gains, including maximum voltage gains and maximum-gain frequencies, for each piezoelectric transformer under different load conditions. Both a piezoelectric buzzer and a gap circle on a silver electrode of the buzzer are needed to build any type of the PTs. Here, the gap circle is used to form a ring-shaped input electrode and a circle-shaped output electrode for each piezoelectric transformer. To do so, both structure and connection of a PT are first expressed. Then, operating principle of a PT and its related vibration mode observed by a carbon-power imaging technique are described. Moreover, an experimental setup for characterizing each piezoelectric transformer is constructed. Finally, effects of diameters of the gap circles on characteristics of voltage gains at different load resistances are discussed.

  2. Instability of warped discs

    Science.gov (United States)

    Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.

    2018-01-01

    Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which in general yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term which would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.

  3. Angular Momentum Transport in Quasi-Keplerian Accretion Disks ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Keplerian accretion disk yield results that are inconsistent with the generally accepted model. If correct, the ideas proposed by Hayashi &. Matsuda would radically alter our understanding of the nature of the angular momentum transport in the disk, ...

  4. The Cluster Orbits With Perturbations of Keplerian Elements (COWPOKE) Equations

    National Research Council Canada - National Science Library

    Sabol, Chris

    2004-01-01

    .... Given mean Keplerian elements and element differences, the COWPOKE equations describe spherical radial, cross-track, and along-track separations of the satellites as an explicit function of time...

  5. Angular Momentum Transport in Quasi-Keplerian Accretion Disks

    Indian Academy of Sciences (India)

    We reexamine arguments advanced by Hayashi & Matsuda (2001), who claim that several simple, physically motivated derivations based on mean free path theory for calculating the viscous torque in a quasi-Keplerian accretion disk yield results that are inconsistent with the generally accepted model. If correct, the ideas ...

  6. Instability of warped discs

    Science.gov (United States)

    Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.

    2018-05-01

    Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further, if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which, in general, yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term that would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ < 0) but is here modified by the warp to include ∂(ν1|ψ|)/∂|ψ| < 0, and (2) a similar condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.

  7. Loop-Mediated Isothermal Amplification Using a Lab-on-a-Disc Device with Thin-film Phase Change Material.

    Science.gov (United States)

    Ko, Junguk; Yoo, Jae-Chern

    2018-03-05

    The design and fabrication of temperature measurement systems that facilitate successful realization of DNA amplification using a lab-on-a-disc (LOD) device are a highly challenging task. The major challenge lies in the fact that such a system must be directly attached to a heating chamber in a way that enables the accurate measurement of temperature of the chamber while allowing the LOD to rotate. This paper presents a temperature control system for implementing isothermal amplification of DNA samples using an LOD device. The proposed system utilizes a thin-film phase change material and non-contact heating system to remotely measure the actual temperature of the chamber and, if required, rapidly heat it to the desired temperature. The results of the experiments performed in this study demonstrate that the proposed system provides an automated platform for molecular amplification and exhibits an operational performance comparable to that of traditional microcentrifuge tube-based isothermal amplification systems.

  8. Thin-section CT in the examination of cervical disc herniation. A prospective study with 1-mm axial and helical images

    Energy Technology Data Exchange (ETDEWEB)

    Ilkko, E. [Dept. of Diagnostic Radiology, Oulu Univ. Central Hospital (Finland); Laehde, S. [Dept. of Diagnostic Radiology, Oulu Univ. Central Hospital (Finland); Heiskari, M. [Dept. of Neurosurgery, Oulu Univ. Central Hospital (Finland)

    1996-03-01

    The aim of the investigation was to determine whether thin-section high-resolution CT imaging could replace MR imaging and/or myelography in preoperative evaluation of radiculopathy and/or myelopathy. A total of 120 patients, referred for cervical myelography (n=107) or MR imaging (n=13), were further examined with 1-mm non-contrast CT of the suspected disc space, including at least the next cephalic and caudal interspaces. Thirty-seven patients underwent Cloward`s operation, at which 32 were found to have disc herniation. The sensitivities of CT (n=37), myelography (n=29), and MR imaging (n=8) were 66%, 84%, and 86%, respectively. The corresponding figures for false-positives were 8%, 10%, and 13%. Artefacts caused by wide shoulders in the 1-mm CT images were estimated to have contributed to a false-negative finding in 8 cases. The remaining 3 false-negatives were retrospectively considered evaluation errors. The true-positive CT findings usually presented with a local disc bulge measuring over 80 HU in density. Local ligamentous hypertropy presented an indistinguishable finding in 3 cases, yielding false-positive CT findings. Conventional thin-section CT is considered a usable alternative for the evaluation of suspected cervical disc herniations in selected patients. Stocky patients with wide shoulders and a short neck are not suitable candidates, even when new generation equipment is available. (orig.).

  9. Thin-section CT in the examination of cervical disc herniation. A prospective study with 1-mm axial and helical images

    International Nuclear Information System (INIS)

    Ilkko, E.; Laehde, S.; Heiskari, M.

    1996-01-01

    The aim of the investigation was to determine whether thin-section high-resolution CT imaging could replace MR imaging and/or myelography in preoperative evaluation of radiculopathy and/or myelopathy. A total of 120 patients, referred for cervical myelography (n=107) or MR imaging (n=13), were further examined with 1-mm non-contrast CT of the suspected disc space, including at least the next cephalic and caudal interspaces. Thirty-seven patients underwent Cloward's operation, at which 32 were found to have disc herniation. The sensitivities of CT (n=37), myelography (n=29), and MR imaging (n=8) were 66%, 84%, and 86%, respectively. The corresponding figures for false-positives were 8%, 10%, and 13%. Artefacts caused by wide shoulders in the 1-mm CT images were estimated to have contributed to a false-negative finding in 8 cases. The remaining 3 false-negatives were retrospectively considered evaluation errors. The true-positive CT findings usually presented with a local disc bulge measuring over 80 HU in density. Local ligamentous hypertropy presented an indistinguishable finding in 3 cases, yielding false-positive CT findings. Conventional thin-section CT is considered a usable alternative for the evaluation of suspected cervical disc herniations in selected patients. Stocky patients with wide shoulders and a short neck are not suitable candidates, even when new generation equipment is available. (orig.)

  10. Local study of helical magnetorotational instability in viscous Keplerian disks

    Science.gov (United States)

    MahdaviGharavi, M.; Hajisharifi, K.; Mehidan, H.

    2018-03-01

    In this paper, regarding the recent detection of significant azimuthal magnetic field in some accretion disks such as protostellar (Donati et al. in Nature 438:466, 2005), the multi-fluid model has been employed to analysis the stability of Keplerian rotational viscous dusty plasma system in a current-free helical magnetic field structure. Using the fluid-Maxwell equations, the general dispersion relation of the excited modes in the system has been obtained by applying the local approximation method in the linear perturbation theory. The typical numerical analysis of the obtained dispersion relation in the high-frequency regime shows that the presence of azimuthal magnetic field component in Keplerian flow has a considerable role in the stability conditions of the system. It also shows that the magnetic field helicity has a stabilization role against the magnetorotational instability (MRI) in the system due to contraction of the unstable wavelength region and decreasing the maximum growth rate of the instability. In this sense, the stabilization role of the viscosity term is more considerable for HMRI (instability in the presence of azimuthal magnetic field component) than the corresponding MRI (instability in the absence of azimuthal magnetic field component). Moreover, considering the discovered azimuthal magnetic field in these systems, the MRI can be arisen in the over-all range of dust grains construction values in contract with traditional MRI. This investigation can greatly contribute to better understanding the physics of some astrophysical phenomena, such as the main source of turbulence and angular momentum transport in protostellar and the other sufficiently ionized astrophysical disks, where the azimuthal magnetic field component in these systems can play a significant role.

  11. Optimal BLS: Optimizing transit-signal detection for Keplerian dynamics

    Science.gov (United States)

    Ofir, Aviv

    2015-08-01

    Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years. We optimize the search for transit signals for both detection and computational efficiencies by assuming that the searched systems can be described by Keplerian, and propagating the effects of different system parameters to the detection parameters. Importnantly, we mainly consider the information content of the transit signal and not any specific algorithm - and use BLS (Kovács, Zucker, & Mazeh 2002) just as a specific example.We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star's size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually.By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the transit signal parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available.

  12. Analytical solution of transient in-plane vibration of a thin viscoelastic disc and its multi-precision evaluation

    Czech Academy of Sciences Publication Activity Database

    Adámek, V.; Valeš, František

    2012-01-01

    Roč. 85, NOV 2012 (2012), s. 34-44 ISSN 0378-4754 R&D Projects: GA ČR(CZ) GAP101/11/0288 Institutional support: RVO:61388998 Keywords : transient vibration * viscoelastic disc * analytical solution Subject RIV: BI - Acoustics Impact factor: 0.836, year: 2012 http://www.sciencedirect.com/science/article/pii/S037847541200225X

  13. VizieR Online Data Catalog: Li enrichment histories of the thick/thin disc (Fu+, 2018)

    Science.gov (United States)

    Fu, X.; Romano, D.; Bragaglia, A.; Mucciarelli, A.; Lind, K.; Delgado Mena, E.; Sousa, S. G.; Randich, S.; Bressan, A.; Sbordone, L.; Martell, S.; Korn, A. J.; Abia, C.; Smiljanic, R.; Jofre, P.; Pancino, E.; Tautvaisiene, G.; Tang, B.; Lanzafame, A. C.; Magrini, L.; Carraro, G.; Bensby, T.; Damiani, F.; Alfaro, E. J.; Flaccomio, E.; Morbidelli, L.; Zaggia, S.; Lardo, C.; Monaco, L.; Frasca, A.; Donati, P.; Drazdauskas, A.; Chorniy, Y.; Bayo, A.; Kordopatis, G.

    2017-11-01

    To investigate the Galactic lithium enrichment history we se- lect well-measured main sequence field stars with UVES spectra from the GES iDR4 catalogue. In our selection, 1884 UVES stars are marked as field stars, including those of the Galactic disc and halo designated as MW (GEMW) fields, standard CoRoT (GES D_CR) field, standard radial velocity (GES DRV) field, and stars to the Galactic Bulge direction (GEMWBL). (1 data file).

  14. Are galaxy discs optically thick?

    International Nuclear Information System (INIS)

    Disney, Michael; Davies, Jonathan; Phillipps, Steven

    1989-01-01

    We re-examine the classical optical evidence for the low optical depths traditionally assigned to spiral discs and argue that it is highly model-dependent and unconvincing. In particular, layered models with a physically thin but optically thick dust layer behave like optically thin discs. The opposite hypotheses, that such discs are optically thick is then examined in the light of modern evidence. We find it to be consistent with the near-infrared and IRAS observations, with the surface brightnesses, with the HI and CO column densities and with the Hα measurements. (author)

  15. Fractal geometry of angular momentum evolution in near-Keplerian systems

    NARCIS (Netherlands)

    Gürkan, M.A.

    2012-01-01

    In this Letter, we propose a method to study the nature of resonant relaxation in near-Keplerian systems. Our technique is based on measuring the fractal dimension of the angular momentum trails and we use it to analyse the outcome of N-body simulations. With our method, we can reliably determine

  16. Polarimetric microlensing of circumstellar discs

    Science.gov (United States)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  17. Artificial Disc Replacement

    Science.gov (United States)

    ... Spondylolisthesis BLOG FIND A SPECIALIST Treatments Artificial Disc Replacement (ADR) Patient Education Committee Jamie Baisden The disc ... Disc An artificial disc (also called a disc replacement, disc prosthesis or spine arthroplasty device) is a ...

  18. A KEPLERIAN-LIKE DISK AROUND THE FORMING O-TYPE STAR AFGL 4176

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Katharine G.; Hoare, Melvin G. [School of Physics and Astronomy, E.C. Stoner Building, The University of Leeds, Leeds LS2 9JT (United Kingdom); Robitaille, Thomas P.; Beuther, Henrik; Linz, Hendrik; Kuiper, Rolf; Boekel, Roy van [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Boley, Paul [Ural Federal University, Astronomical Observatory, 51 pr. Lenina, Ekaterinburg (Russian Federation); Keto, Eric, E-mail: k.g.johnston@leeds.ac.uk [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-11-01

    We present Atacama Large Millimeter/submillimeter Array line and continuum observations at 1.2 mm with ∼0.″3 resolution that uncover a Keplerian-like disk around the forming O-type star AFGL 4176. The continuum emission from the disk at 1.21 mm (source mm1) has a deconvolved size of 870 ± 110 AU × 330 ± 300 AU and arises from a structure ∼8 M{sub ⊙} in mass, calculated assuming a dust temperature of 190 K. The first-moment maps, pixel-to-pixel line modeling, assuming local thermodynamic equilibrium (LTE), and position–velocity diagrams of the CH{sub 3}CN J = 13–12 K-line emission all show a velocity gradient along the major axis of the source, coupled with an increase in velocity at small radii, consistent with Keplerian-like rotation. The LTE line modeling shows that where CH{sub 3}CN J = 13–12 is excited, the temperatures in the disk range from ∼70 to at least 300 K and that the H{sub 2} column density peaks at 2.8 × 10{sup 24} cm{sup −2}. In addition, we present Atacama Pathfinder Experiment {sup 12}CO observations that show a large-scale outflow from AFGL 4176 perpendicular to the major axis of mm1, supporting the disk interpretation. Finally, we present a radiative transfer model of a Keplerian disk surrounding an O7 star, with a disk mass and radius of 12 M{sub ⊙} and 2000 AU that reproduces the line and continuum data, further supporting our conclusion that our observations have uncovered a Keplerian-like disk around an O-type star.

  19. Evolutionary Dynamics While Trapped in Resonance: A Keplerian Binary System Perturbed by Gravitational Radiation

    OpenAIRE

    Chicone, Carmen; Mashhoon, Bahram; Retzloff, David

    1996-01-01

    The method of averaging is used to investigate the phenomenon of capture into resonance for a model that describes a Keplerian binary system influenced by radiation damping and external normally incident periodic gravitational radiation. The dynamical evolution of the binary orbit while trapped in resonance is elucidated using the second order partially averaged system. This method provides a theoretical framework that can be used to explain the main evolutionary dynamics of a physical system...

  20. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Olivares, Marco [Universidad Diego Portales, Avenida Ejercito Libertador 441, Facultad de Ingenieria, Santiago (Chile)

    2015-11-15

    Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics. (orig.)

  1. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J. R., E-mail: jose.villanuevalob@uv.cl [Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Valparaíso (Chile); Centro de Astrofísica de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso (Chile); Olivares, Marco, E-mail: marco.olivaresr@mail.udp.cl [Facultad de Ingeniería, Universidad Diego Portales, Avenida Ejército Libertador 441, Casilla 298–V, Santiago (Chile)

    2015-11-27

    Properties of the motion of electrically charged particles in the background of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41–48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.

  2. Forming spectroscopic massive protobinaries by disc fragmentation

    Science.gov (United States)

    Meyer, D. M.-A.; Kuiper, R.; Kley, W.; Johnston, K. G.; Vorobyov, E.

    2018-01-01

    The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary companions which will later strongly influence the star's future evolution in the Hertzsprung-Russel diagram. We present three-dimensional gravitation-radiation-hydrodynamic numerical simulations of 100 M⊙ pre-stellar cores. We find that accretion discs of young massive stars violently fragment without preventing the (highly variable) accretion of gaseous clumps on to the protostars. While acquiring the characteristics of a nascent low-mass companion, some disc fragments migrate on to the central massive protostar with dynamical properties showing that its final Keplerian orbit is close enough to constitute a close massive protobinary system, having a young high- and a low-mass components. We conclude on the viability of the disc fragmentation channel for the formation of such short-period binaries, and that both processes - close massive binary formation and accretion bursts - may happen at the same time. FU-Orionis-type bursts, such as observed in the young high-mass star S255IR-NIRS3, may not only indicate ongoing disc fragmentation, but also be considered as a tracer for the formation of close massive binaries - progenitors of the subsequent massive spectroscopic binaries - once the high-mass component of the system will enter the main-sequence phase of its evolution. Finally, we investigate the Atacama Large (sub-)Millimeter Array observability of the disc fragments.

  3. On the Dynamical Structure of the Jet System in the Disk with the Keplerian Rotation

    Directory of Open Access Journals (Sweden)

    Kyung-Sook Jeong

    1989-06-01

    Full Text Available The classical sloar wind theory proposed by Parker(1963 explains well the dynamics of the wind pheonomena such as stellar wind accretion disk. While the stellar wind system like the solar wind has the spherically symmetric wind structure, there are various jet phenomena which collimate the system into the narrow space. We can find these dynamical structures in SS433, in the optical jet of M87, and around the active galactic nulei. We present the dynamical structure of the jet system in disks, which conserves the angular momentum, with the Keplerian rotation and the strong relation between the geometrical cross section and the physical change of the jet stream on the basis of the hydrodynamic equations.

  4. SAT-LAB: A MATLAB Graphical User Interface for simulating and visualizing Keplerian satellite orbits

    Science.gov (United States)

    Piretzidis, Dimitrios; Sideris, Michael G.

    2017-04-01

    SAT-LAB is a MATLAB-based Graphical User Interface (GUI), developed for simulating and visualizing satellite orbits. The primary purpose of SAT-LAB is to provide software with a user-friendly interface that can be used for both academic and scientific purposes. For the simulation of satellite orbits, a simple Keplerian propagator is used. The user can select the six Keplerian elements, and the simulation and visualization of the satellite orbit is performed simultaneously, in real time. The satellite orbit and the state vector, i.e., satellite position and velocity, at each epoch is given in the Inertial Reference Frame (IRF) and the Earth-Fixed Reference Frame (EFRF). For the EFRF, both the 3D Cartesian coordinates and the ground tracks of the orbit are provided. Other visualization options include selection of the appearance of the Earth's coastline and topography/bathymetry, the satellite orbit, position, velocity and radial distance, and the IRF and EFRF axes. SAT-LAB is also capable of predicting and visualizing orbits of operational satellites. The software provides the ability to download orbital elements and other information of operational satellites in the form of Two-Line Element sets. The user can choose among 41 satellite categories, including geodetic, communications, navigation, and weather satellites, as well as space debris from past satellite missions or collisions. Real-time tracking of the position of operational satellites is also available. All the capabilities of SAT-LAB software are demonstrated by providing simulation examples of geostationary, highly elliptical and near polar orbits. Also, visualization examples of operational satellite orbits, such as GNSS and LEO satellites, are given.

  5. Herniated lumbar disc

    OpenAIRE

    Jordon, Jo; Konstantinou, Kika; O'Dowd, John

    2009-01-01

    Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30-50 years, with a male to female ratio of 2:1.

  6. Herniated lumbar disc

    OpenAIRE

    Jordan, Jo; Konstantinou, Kika; O'Dowd, John

    2011-01-01

    Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1.

  7. Viscous Effects on the Interaction between the Coplanar Decretion Disc and the Neutron Star in Be/X-Ray Binaries

    OpenAIRE

    Okazaki, A. T.; Bate, M. R.; Ogilvie, G. I.; Pringle, J. E.

    2002-01-01

    We study the viscous effects on the interaction between the coplanar Be-star disc and the neutron star in Be/X-ray binaries, using a three-dimensional, smoothed particle hydrodynamics code. For simplicity, we assume the Be disc to be isothermal at the temperature of half the stellar effective temperature. In order to mimic the gas ejection process from the Be star, we inject particles with the Keplerian rotation velocity at a radius just outside the star. Both Be star and neutron star are tre...

  8. Exact Delaunay normalization of the perturbed Keplerian Hamiltonian with tesseral harmonics

    Science.gov (United States)

    Mahajan, Bharat; Vadali, Srinivas R.; Alfriend, Kyle T.

    2018-03-01

    A novel approach for the exact Delaunay normalization of the perturbed Keplerian Hamiltonian with tesseral and sectorial spherical harmonics is presented in this work. It is shown that the exact solution for the Delaunay normalization can be reduced to quadratures by the application of Deprit's Lie-transform-based perturbation method. Two different series representations of the quadratures, one in powers of the eccentricity and the other in powers of the ratio of the Earth's angular velocity to the satellite's mean motion, are derived. The latter series representation produces expressions for the short-period variations that are similar to those obtained from the conventional method of relegation. Alternatively, the quadratures can be evaluated numerically, resulting in more compact expressions for the short-period variations that are valid for an elliptic orbit with an arbitrary value of the eccentricity. Using the proposed methodology for the Delaunay normalization, generalized expressions for the short-period variations of the equinoctial orbital elements, valid for an arbitrary tesseral or sectorial harmonic, are derived. The result is a compact unified artificial satellite theory for the sub-synchronous and super-synchronous orbit regimes, which is nonsingular for the resonant orbits, and is closed-form in the eccentricity as well. The accuracy of the proposed theory is validated by comparison with numerical orbit propagations.

  9. Transverse Cascade and Sustenance of Turbulence in Keplerian Disks with an Azimuthal Magnetic Field

    Science.gov (United States)

    Gogichaishvili, D.; Mamatsashvili, G.; Horton, W.; Chagelishvili, G.; Bodo, G.

    2017-10-01

    The magnetorotational instability (MRI) in the sheared rotational Keplerian explains fundamental problems for both astrophysics and toroidal laboratory plasmas. The turbulence occurs before the threshold for the linear eigen modes. The work shows the turbulence occurs in nonzero toroidal magnetic field with a sheared toroidal flow velocity. We analyze the turbulence in Fourier k-space and x-space each time step to clarify the nonlinear energy-momentum transfers that produce the sustenance in the linearly stable plasma. The nonlinear process is a type 3D angular redistribution of modes in Fourier space - a transverse cascade - rather than the direct/inverse cascades. The turbulence is sustained an interplay of the linear transient growth from the radial gradient of the toroidal velocity (which is the only energy supply for the turbulence) and the transverse cascade. There is a relatively small ``vital area in Fourier space'' is crucial for the sustenance. Outside the vital area the direct cascade dominates. The interplay of the linear and nonlinear processes is generally too intertwined in k-space for a classical turbulence characterization. Subcycles occur from the interactions that maintain self-organization nonlinear turbulence. The spectral characteristics in four simulations are similar showing the universality of the sustenance mechanism of the shear flow driven MHDs-turbulence. Funded by the US Department of Energy under Grant DE-FG02-04ER54742 and the Space and Geophysics Laboratory at the University of Texas at Austin. G. Mamatsashvili is supported by the Alexander von Humboldt Foundation, Germany.

  10. Population synthesis to constrain Galactic and stellar physics. I. Determining age and mass of thin-disc red-giant stars

    Science.gov (United States)

    Lagarde, N.; Robin, A. C.; Reylé, C.; Nasello, G.

    2017-05-01

    Context. The cornerstone mission of the European Space Agency, Gaia, together with forthcoming complementary surveys (CoRoT, Kepler, K2, APOGEE, and Gaia-ESO), will revolutionize our understanding of the formation and history of our Galaxy, providing accurate stellar masses, radii, ages, distances, as well as chemical properties for a very large sample of stars across different Galactic stellar populations. Aims: Using an improved population synthesis approach and new stellar evolution models we attempt to evaluate the possibility of deriving ages and masses of clump stars from their chemical properties. Methods: A new version of the Besançon Galaxy models (BGM) is used in which new stellar evolutionary tracks are computed from the stellar evolution code STAREVOL. These provide global, chemical, and seismic properties of stars from the pre-main sequence to the early-AGB. For the first time, the BGM can explore the effects of an extra-mixing occurring in red-giant stars. In particular we focus on the effects of thermohaline instability on chemical properties as well as on the determination of stellar ages and masses using the surface [C/N] abundance ratio. Results: The impact of extra-mixing on 3He, 12C/13C, nitrogen, and [C/N] abundances along the giant branch is quantified. We underline the crucial contribution of asteroseismology to discriminate between evolutionary states of field giants belonging to the Galactic disc. The inclusion of thermohaline instability has a significant impact on 12C/13C, 3He as well as on the [C/N] values. We clearly show the efficiency of thermohaline mixing at different metallicities and its influence on the determined stellar mass and age from the observed [C/N] ratio. We then propose simple relations to determine ages and masses from chemical abundances according to these models. Conclusions: We emphasize the usefulness of population synthesis tools to test stellar models and transport processes inside stars. We show that transport

  11. The reports of thick discs' deaths are greatly exaggerated. Thick discs are NOT artefacts caused by diffuse scattered light

    Science.gov (United States)

    Comerón, S.; Salo, H.; Knapen, J. H.

    2018-02-01

    Recent studies have made the community aware of the importance of accounting for scattered light when examining low-surface-brightness galaxy features such as thick discs. In our past studies of the thick discs of edge-on galaxies in the Spitzer Survey of Stellar Structure in Galaxies - the S4G - we modelled the point spread function as a Gaussian. In this paper we re-examine our results using a revised point spread function model that accounts for extended wings out to more than 2\\farcm5. We study the 3.6 μm images of 141 edge-on galaxies from the S4G and its early-type galaxy extension. Thus, we more than double the samples examined in our past studies. We decompose the surface-brightness profiles of the galaxies perpendicular to their mid-planes assuming that discs are made of two stellar discs in hydrostatic equilibrium. We decompose the axial surface-brightness profiles of galaxies to model the central mass concentration - described by a Sérsic function - and the disc - described by a broken exponential disc seen edge-on. Our improved treatment fully confirms the ubiquitous occurrence of thick discs. The main difference between our current fits and those presented in our previous papers is that now the scattered light from the thin disc dominates the surface brightness at levels below μ 26 mag arcsec-2. We stress that those extended thin disc tails are not physical, but pure scattered light. This change, however, does not drastically affect any of our previously presented results: 1) Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 2) Thick discs have masses comparable to those of thin discs in low-mass galaxies - with circular velocities vc< 120 km s-1 - whereas they are typically less massive than the thin discs in high-mass galaxies. 3) Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir. 4) Approximately 50% of the up

  12. Herniated Cervical Disc

    Science.gov (United States)

    ... and inflammation that occur as a result of disc herniation. These include aspirin, ibuprofen, naproxen and a variety ... many factors including the exact location of the disc herniation and the experience and preference of the surgeon. ...

  13. Quasi-static transient thermal stresses in a thick annular disc

    Indian Academy of Sciences (India)

    in a thin annular disc. Also Deshmukh 2002 studied transient heat conduction problem in a thin hollow cylinder and determined thermal stresses. ... containers for hot gases or liquids, in the foundations for furnaces, etc. 2. Formulation of the problem. Consider a thick a annular disc of thickness 2h occupying space D defined ...

  14. Radially truncated galactic discs

    NARCIS (Netherlands)

    Grijs, R. de; Kregel, M.; Wesson, K H

    2000-01-01

    Abstract: We present the first results of a systematic analysis of radially truncatedexponential discs for four galaxies of a sample of disc-dominated edge-onspiral galaxies. Edge-on galaxies are very useful for the study of truncatedgalactic discs, since we can follow their light distributions out

  15. Design of an Annular Disc Subject to Thermomechanical Loading

    Directory of Open Access Journals (Sweden)

    Sergei Alexandrov

    2012-01-01

    Full Text Available Two solutions to design a thin annular disc of variable thickness subject to thermomechanical loading are proposed. It is assumed that the thickness of the disc is everywhere sufficiently small for the stresses to be averaged through the thickness. The state of stress is plane. The initiation of plastic yielding is controlled by Mises yield criterion. The design criterion for one of the solutions proposed requires that the distribution of stresses is uniform over the entire disc. In this case there is a relation between optimal values of the loading parameters at the final stage. The specific shape of the disc corresponds to each pair of such parameters. The other solution is obtained under the additional requirement that the distribution of strains is uniform. This solution exists for the disc of constant thickness at specific values of the loading parameters.

  16. Disc operational system

    International Nuclear Information System (INIS)

    Veretenov, V.Yu.; Volkov, A.I.; Gurevich, M.I.; Kozik, V.S.; Pod'yachev, E.I.; Shapiro, M.L.

    1974-01-01

    A disc operational system is proposed, which is based on the file structure and designed for use in a BESM-6 computer with the software system comprising a dispatcher DD-73 and a monitor 'Dubna'. The main distinguishing feature of the disc operational system is the decentralization of the file system. Each disc package is an independent file unaffected by the state of the other disc packages. The use of several disc packages is allowed. The above feature of the disc operational system makes it possible to simplify the language of communication with the system, to give the user the opportunity of controlling the file quite independently, and to simplify the maintenance of the discs by the computer personnel. One and the same disc can be simultaneously addressed by all problems in the processor (both mathematical and service). A single file, however, may be used in the recording mode by only one problem. The description presented is the instruction for users. It also describes special possibilities open to the system programmers [ru

  17. Intratracheal Seal Disc

    DEFF Research Database (Denmark)

    Christiansen, Karen J; Moeslund, Niels; Lauridsen, Henrik

    2017-01-01

    21, CT was repeated before euthanasia. The trachea and epidermis were excised en bloc for histopathological evaluation. RESULTS: Insertion and correct placement of the disc was unproblematic in all animals. CT at day 14 confirmed a clear airway, appropriate placement of the disc, and full closure...

  18. Simple discs with flat roatation curves

    Science.gov (United States)

    Evans, N. W.; Collett, J. L.

    1993-09-01

    The aim of this paper is to understand why the squared axial ratio of the velocity ellipse, σphi_^2^/σ_R_^2^, of old disc stars in the Galaxy is less than 1/2. To this end, two infinitesimally thin steady-state axisymmetric discs with asymptotically flat circular velocity curves are presented. The first model - which we designate the Rybicki disc has surface density decaying inversely with radius. The second model is Freeman's exponential disc, which is immersed in the gravity field of the halo simulated by Mestel's potential. For both discs, we provide an infinite family of simple distribution functions, which form a sequence of increasing pressure support. In the Rybicki disc, the stellar streaming velocity increases outwards with radius, which typically causes σphi_^2^/σ_R_^2^ to be greater than 1/2. For our exponential disc distribution functions, the stellar streaming velocity declines outwards with radius, which typically causes σphi^2^/σ_R_^2^ to be less than 1/2. Our exponential disc distribution functions have the property that σ_R_^2^ decays only inversely with galactocentric radius R. If the diminution is faster, the ratio σphi_^2^/σ_R_^2^ rises above 1/2 at the Sun as the mean streaming velocity declines only in the inner disk. To investigate this, exponential discs with exponentially falling radial velocity dispersion are built. These are in conflict with the observations on the axial ratio, even allowing for a mismatch in the photometric and kinematic scalelengths. There are a number of possible resolutions of the contradiction: (1) the galactic disc is not in a steady state or is non-axisymmetric; (2) the circular velocity curve is locally declining; (3) the description of all stellar populations by a single distribution function is invalid; (4) the radial velocity dispersion does not drop off exponentially fast, but much more slowly; (5) the sampling of moving clusters and transient associations of stars creates a biased data set.

  19. Structure of protoplanetary discs with magnetically driven winds

    Science.gov (United States)

    Khajenabi, Fazeleh; Shadmehri, Mohsen; Pessah, Martin E.; Martin, Rebecca G.

    2018-04-01

    We present a new set of analytical solutions to model the steady-state structure of a protoplanetary disc with a magnetically driven wind. Our model implements a parametrization of the stresses involved and the wind launching mechanism in terms of the plasma parameter at the disc midplane, as suggested by the results of recent, local magnetohydrodynamical simulations. When wind mass-loss is accounted for, we find that its rate significantly reduces the disc surface density, particularly in the inner disc region. We also find that models that include wind mass-loss lead to thinner dust layers. As an astrophysical application of our models, we address the case of HL Tau, whose disc exhibits a high accretion rate and efficient dust settling at its midplane. These two observational features are not easy to reconcile with conventional accretion disc theory, where the level of turbulence needed to explain the high accretion rate would prevent a thin dust layer. Our disc model that incorporates both mass-loss and angular momentum removal by a wind is able to account for HL Tau observational constraints concerning its high accretion rate and dust layer thinness.

  20. An affine model of the dynamics of astrophysical discs

    Science.gov (United States)

    Ogilvie, Gordon I.

    2018-03-01

    Thin astrophysical discs are very often modelled using the equations of two-dimensional hydrodynamics. We derive an extension of this model that describes more accurately the behaviour of a thin disc in the absence of self-gravity, magnetic fields and complex internal motions. The ideal fluid theory is derived directly from Hamilton's Principle for a three-dimensional fluid after making a specific approximation to the deformation gradient tensor. We express the equations in Eulerian form after projection on to a reference plane. The disc is thought of as a set of fluid columns, each of which is capable of a time-dependent affine transformation, consisting of a translation together with a linear transformation in three dimensions. Therefore, in addition to the usual two-dimensional hydrodynamics in the reference plane, the theory allows for a deformation of the midplane (as occurs in warped discs) and for the internal shearing motions that accompany such deformations. It also allows for the vertical expansions driven in non-circular discs by a variation of the vertical gravitational field around the horizontal streamlines, or by a divergence of the horizontal velocity. The equations of the affine model embody conservation laws for energy and potential vorticity, even for non-planar discs. We verify that they reproduce exactly the linear theories of three-dimensional warped and eccentric discs in a secular approximation. However, the affine model does not rely on any secular or small-amplitude assumptions and should be useful in more general circumstances.

  1. Solar neighbourhood and Galactic disc(s: New constraints

    Directory of Open Access Journals (Sweden)

    Schönrich R.

    2012-02-01

    Full Text Available We present a re-analysis of the Geneva-Copenhagen survey, based on improved effective temperature and metallicity scales, which also provide a better match to theoretical isochrones. The latter are used for a Bayesian investigation on stellar ages. With respect to previous analyses, our stars are on average 100 K hotter and 0.1 dex more metal rich, which shifts the peak of the metallicity distribution function around the solar value. From Strömgren photometry we are able to derive for the first time a proxy for alpha elements, which enables us to perform a tentative dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha-enhanced population that extends to super solar metallicities, in agreement with spectroscopic studies. Our analysis suggests a strong interplay among ages, abundances and kinematics of stars.

  2. Optic disc oedema

    DEFF Research Database (Denmark)

    Nielsen, Marianne Kromann; Hamann, Steffen

    2014-01-01

    Optic disc oedema describes the nonspecific, localized swelling of the optic nerve head regardless of aetiology. Therefore, differentiating among the various aetiologies depends on a thorough history and knowledge of the clinical characteristics of the underlying conditions. Papilloedema strictly...... refers to optic disc oedema as a consequence of elevated intracranial pressure. It is usually a bilateral condition and visual function is preserved until late. Optic disc oedema caused by an anterior optic neuropathy is usually unilateral and accompanied by the loss of visual function....

  3. The effects of a hot gaseous halo on disc thickening in galaxy minor mergers

    Science.gov (United States)

    Moster, Benjamin P.; Macciò, Andrea V.; Somerville, Rachel S.; Naab, Thorsten; Cox, T. J.

    2012-07-01

    We employ hydrodynamical simulations to study the effects of dissipational gas physics on the vertical heating and thickening of disc galaxies during minor mergers. For the first time we present a suite of simulations that includes a diffuse, rotating, cooling, hot gaseous halo, as predicted by cosmological hydrodynamical simulations as well as models of galaxy formation. We study the effect of this new gaseous component on the vertical structure of a Milky Way-like stellar disc during 1:10 and 1:5 mergers. For 1:10 mergers, we find no increased final thin disc scale height compared to the isolated simulation, leading to the conclusion that thin discs can be present even after a 1:10 merger if a reasonable amount of hot gas is present. The reason for this is the accretion of new cold gas, leading to the formation of a massive new thin stellar disc that dominates the surface brightness profile. In a previous study, in which we included only cold gas in the disc, we showed that the presence of cold gas decreased the thickening by a minor merger relative to the no-gas case. Here, we show that the evolution of the scale height in the presence of a cooling hot halo is dominated by the formation of the new stellar disc. In this scenario, the thick disc is the old stellar disc that has been thickened in a minor merger at z≳ 1, while the thin disc is the new stellar disc that reforms after this merger. When galactic winds are also considered, the final scale height is larger due to two effects. First, the winds reduce the star formation rate, leading to a less massive new stellar disc, such that the thickened old disc still dominates. Secondly, the winds exert a pressure force on the gas in the disc, leading to a shallower gas profile and thus to a thicker new stellar disc. In addition, we study the evolution of the scale height during a 1:5 merger and find that a thin disc can be present even after this merger, provided enough hot gas is available. The final scale

  4. Pseudoenhancement of intervertebral disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Y.; Ootani, M.; Furukawa, T.; Tsukaguchi, I. (Dept. of Radiology, Osaka Rosai Hospital (Japan)); Mitomo, M. (Dept. of Radiology, Osaka Univ. Medical School (Japan))

    1992-08-01

    Two patients with intervertebral disc herniation appeared to demonstrate abnormally diffuse and intense enhancement of the disc after intravenous administration of gadolinium-DTPA for MRI. Surgery disclosed a dilated epidural venous plexus in one and vascular granulation tissue in the other, associated with the herniated disc material. The mechanism of this 'pseudoenhancement' of the disc appears to be a partial volume effect of disc material and the adjacent veins or granulation tissue. Pseudoenhancement of a herniated disc should be included in the differential diagnosis of a diffusely enhancing epidural mass. (orig.).

  5. Cervical intervertebral disc replacement.

    Science.gov (United States)

    Cason, Garrick W; Herkowitz, Harry N

    2013-02-06

    Symptomatic adjacent-level disease after cervical fusion has led to the development and testing of several disc-replacement prostheses. Randomized controlled trials of cervical disc replacement (CDR) compared with anterior cervical discectomy and fusion (ACDF) have demonstrated at least equivalent clinical results for CDR with similar or lower complication rates. Biomechanical, kinematic, and radiographic studies of CDR reveal that the surgical level and adjacent vertebral level motion and center of rotation more closely mimic the native state. Lower intradiscal pressures adjacent to CDR may help decrease the incidence of adjacent spinal-level disease, but long-term follow-up is necessary to evaluate this theory.

  6. Isolated Optic Disc Tuberculosis

    Science.gov (United States)

    Mansour, Ahmad M.; Tabbara, Khalid F.; Tabbarah, Zuhair

    2015-01-01

    We present a healthy male subject who developed progressive visual loss in the left eye initially diagnosed as optic neuritis. Upon suspicion of infectious etiology, testing was positive for tuberculosis. There were no signs or symptoms of active systemic tuberculosis infection. The patient responded swiftly to antimycobacterial therapy with return of vision and resolution of disc swelling. Positive purified protein derivative skin test, negative chest radiograph, negative systemic workup, negative workup for other causes of unilateral optic neuritis and quick response to mycobacterial therapy reaffirm the entity of isolated optic disc tuberculosis similar to isolated choroidal tuberculosis without systemic manifestation. PMID:26483675

  7. Isolated Optic Disc Tuberculosis

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour

    2015-09-01

    Full Text Available We present a healthy male subject who developed progressive visual loss in the left eye initially diagnosed as optic neuritis. Upon suspicion of infectious etiology, testing was positive for tuberculosis. There were no signs or symptoms of active systemic tuberculosis infection. The patient responded swiftly to antimycobacterial therapy with return of vision and resolution of disc swelling. Positive purified protein derivative skin test, negative chest radiograph, negative systemic workup, negative workup for other causes of unilateral optic neuritis and quick response to mycobacterial therapy reaffirm the entity of isolated optic disc tuberculosis similar to isolated choroidal tuberculosis without systemic manifestation.

  8. Observing the On-going Formation of Planets and its Effects on Their Parent Discs

    Science.gov (United States)

    Willson, Matthew Alexander

    2017-06-01

    immediately outside of a ring of dusty material largely responsible for the NIR comment of the disc SED, similar to TW Hya b located in a shallow gap in the dust disc outside another ring of over-dense dusty material which bounds a deep but narrow gap. Both of these companion candidates maybe migrating cores which are feeding from the enriched ring of material. I conducted a more extensive study of the pre-transitional disc, V1247 Ori, covering three epochs and the H-, K- and L-wavebands. Complementary observations with VLT/SPHERE in Hα and continuum plus SMA observations in CO (2-1) and continuum were performed. The orientation and geometry of the outer disc was recovered with the SMA data and determine the direction of rotation. We image the inner rim of the outer disc in L-band SAM data, recovering the rim in all three epochs. Combining all three data sets together we form a detailed image of the rim. In H- and K-band SAM data we observe the motion of a close-in companion candidate. This motion was found to be too large to be adequately explained through a near-circular Keplerian orbit within the plane of the disc around the central star. Hence an alternate hypothesis had to be developed. I postulated that the fitted position of the companion maybe influenced by the emission from the disc rim seen in the L-band SAM data. I constructed a suite of model SAM data sets of a companion and a disc rim and found that under the right conditions the fitted separation of a companion will be larger than the true separation. Under these conditions we find the motion of the companion candidate to be consistent with a near-circular Keplerian orbit within the plane of the disc at a semi-major axis of ˜6 au. The Hα data lack the necessary resolution to confirm the companion as an accreting body, but through the high contrast sensitivities enabled by the state of the art SPHERE instrument I was able to rule out any other accreting body within the gap, unless deeply embedded by the sparse

  9. Magnetized advective accretion flows: formation of magnetic barriers in Magnetically Arrested Discs

    Science.gov (United States)

    Mondal, Tushar; Mukhopadhyay, Banibrata

    2018-02-01

    We discuss the importance of large scale strong magnetic field in the removal of angular momentum outward, as well as the possible origin of different kinds of magnetic barrier in advective, geometrically thick, sub-Keplerian accretion flows around black holes. The origin of this large scale strong magnetic field near the event horizon is due to the advection of the magnetic flux by the accreting gas from the environment, say, the interstellar medium or a companion star, because of flux freezing. In this simplest vertically averaged, 1.5 -dimensional disc model, we choose the maximum upper limit of the magnetic field, which the disc around a black hole can sustain. In this so called magnetically arrested disc (MAD) model, the accreting gas either decelerates or faces the magnetic barrier near the event horizon by the accumulated magnetic field depending on the geometry. The magnetic barrier may knock the matter to infinity. We suggest that these types of flow are the building block to produce jets and outflows in the accreting system. We also find that in some cases, when matter is trying to go back to infinity after knocking the barrier, matter is prevented being escaped by the cumulative action of strong gravity and the magnetic tension, hence by another barrier. In this way, magnetic field can lock the matter in between these two barriers and it might be a possible explanation for the formation of episodic jet.

  10. Magnetized advective accretion flows: formation of magnetic barriers in magnetically arrested discs

    Science.gov (United States)

    Mondal, Tushar; Mukhopadhyay, Banibrata

    2018-05-01

    We discuss the importance of large-scale strong magnetic field in the removal of angular momentum outward, as well as the possible origin of different kinds of magnetic barrier in advective, geometrically thick, sub-Keplerian accretion flows around black holes. The origin of this large-scale strong magnetic field near the event horizon is due to the advection of the magnetic flux by the accreting gas from the environment, say, the interstellar medium or a companion star, because of flux freezing. In this simplest vertically averaged, 1.5-dimensional disc model, we choose the maximum upper limit of the magnetic field, which the disc around a black hole can sustain. In this so called magnetically arrested disc model, the accreting gas either decelerates or faces the magnetic barrier near the event horizon by the accumulated magnetic field depending on the geometry. The magnetic barrier may knock the matter to infinity. We suggest that these types of flow are the building block to produce jets and outflows in the accreting system. We also find that in some cases, when matter is trying to go back to infinity after knocking the barrier, matter is prevented being escaped by the cumulative action of strong gravity and the magnetic tension, hence by another barrier. In this way, magnetic field can lock the matter in between these two barriers and it might be a possible explanation for the formation of episodic jet.

  11. Tracing Planets in Circumstellar Discs

    Directory of Open Access Journals (Sweden)

    Uribe Ana L.

    2013-04-01

    Full Text Available Planets are assumed to form in circumstellar discs around young stellar objects. The additional gravitational potential of a planet perturbs the disc and leads to characteristic structures, i.e. spiral waves and gaps, in the disc density profile. We perform a large-scale parameter study on the observability of these planet-induced structures in circumstellar discs in the (submm wavelength range for the Atacama Large (SubMillimeter Array (ALMA. On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disc-planet models we calculate the disc temperature structure and (submm images of these systems. These are used to derive simulated ALMA maps. Because appropriate objects are frequent in the Taurus-Auriga region, we focus on a distance of 140 pc and a declination of ≈ 20°. The explored range of star-disc-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses, nine disc sizes with outer radii ranging from 9 AU to 225 AU, 15 total disc masses in the range between 2.67·10-7 M⊙ and 4.10·10-2 M⊙, six different central stars and two different grain size distributions, resulting in 10 000 disc models. At almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disc structures induced by planet-disc interaction or the influence of magnetic fields in the wavelength range between 0.4...2.0 mm. In most cases, the optimum angular resolution is limited by the sensitivity of ALMA. However, within the range of typical masses of protoplane tary discs (0.1 M⊙...0.001 M⊙ the disc mass has a minor impact on the observability. At the distance of 140 pc it is possible to resolve discs down to 2.67·10-6 M⊙ and trace gaps in discs with 2.67·10-4 M⊙ with a signal-to-noise ratio greater than three. In general, it is more likely to trace planet-induced gaps in magneto-hydrodynamical disc models, because gaps are wider in the presence of

  12. The DISC Quotient

    Science.gov (United States)

    Elliott, John R.; Baxter, Stephen

    2012-09-01

    D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

  13. Optic disc drusen

    DEFF Research Database (Denmark)

    Fledelius, Hans C

    2017-01-01

    , which, in view of the small disc at risk, may seem a paradox. METHODS: This is an observational retrospective study on an eye clinic series (n = 49), focusing on visual acuity, kinetic/static perimetry, and longitudinal trends, to include the question of eventual visual incapacity. RESULTS: Forty...

  14. LUMBAR DISC HERNIATION

    Science.gov (United States)

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  15. Wave disc engine apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Norbert; Piechna, Janusz; Sun, Guangwei; Parraga, Pablo-Francisco

    2018-01-02

    A wave disc engine apparatus is provided. A further aspect employs a constricted nozzle in a wave rotor channel. A further aspect provides a sharp bend between an inlet and an outlet in a fluid pathway of a wave rotor, with the bend being spaced away from a peripheral edge of the wave rotor. A radial wave rotor for generating electricity in an automotive vehicle is disclosed in yet another aspect.

  16. Cervical Total Disc Arthroplasty

    OpenAIRE

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc...

  17. Total disc replacement.

    Science.gov (United States)

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Anterolateral Approach for Central Thoracic Disc Prolapse-Surgical Strategies Used to Tackle Differing Operative Findings: 3-Dimensional Operative Video.

    Science.gov (United States)

    Patel, Krunal; Budohoski, Karol P; Kenyon, Olivia R P; Barone, Damiano G; Santarius, Thomas; Kirollos, Ramez W; Mannion, Richard J; Trivedi, Rikin A

    2018-04-02

    Thoracic disc prolapses causing cord compression can be challenging. For compressive central disc protrusions, a posterior approach is not suitable due to an unacceptable level of cord manipulation. An anterolateral transthoracic approach provides direct access to the disc prolapse allowing for decompression without disturbing the spinal cord. In this video, we describe 2 cases of thoracic myelopathy from a compressive central thoracic disc prolapse. In both cases, informed consent was obtained. Despite similar radiological appearances of heavy calcification, intraoperatively significant differences can be encountered. We demonstrate different surgical strategies depending on the consistency of the disc and the adherence to the thecal sac. With adequate exposure and detachment from adjacent vertebral bodies, soft discs can be, in most instances, separated from the theca with minimal cord manipulation. On the other hand, largely calcified discs often present a significantly greater challenge and require thinning the disc capsule before removal. In cases with significant adherence to dura, in order to prevent cord injury or cerebrospinal fluid leak a thinned shell can be left, providing total detachment from adjacent vertebrae can be achieved. Postoperatively, the first patient, with a significantly calcified disc, developed a transient left leg weakness which recovered by 3-month follow-up. This video outlines the anatomical considerations and operative steps for a transthoracic approach to a central disc prolapse, whilst demonstrating that computed tomography appearances are not always indicative of potential operative difficulties.

  19. [Temporomandibular joint disc surgery].

    Science.gov (United States)

    Potier, J; Maes, J-M; Nicot, R; Dumousseau, T; Cotelle, M; Ferri, J

    2016-09-01

    Temporomandibular joint (TMJ) disorders are a common disease and may be responsible for major functional and painful repercussions. Treatment is not consensual. The literature highlights the role of conservative treatments (physiotherapy, analgesics, splints) in a first attempt. Minimally invasive surgical techniques (arthroscopy, arthrocentesis) have developed rapidly in recent decades. They have proven effective and reliable, especially in patients suffering from irreducible or reducible anterior disc dislocation or presenting with arthopathies. The goal of our work was to make an update about disk surgery. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  20. Herniated lumbar disc: injection interventions for sciatica

    OpenAIRE

    Jordan, Joanne L; Konstantinou, Kika; O'Dowd, John

    2016-01-01

    Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosus) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1.

  1. Gravitating discs around black holes

    International Nuclear Information System (INIS)

    Karas, V; Hure, J-M; Semerak, O

    2004-01-01

    Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole-disc system using analytical solutions of stationary, axially symmetric Einstein equations. Then, more detailed considerations are focused to the middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate. Within general relativity, only a static case has been analysed in detail. Results are often very inspiring. However, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging are completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the surrounding environment. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star-disc interactions, which can be recognized in observational properties, such as the relation between the central mass and stellar velocity dispersion. (topical review)

  2. Radicular interdural lumbar disc herniation

    Science.gov (United States)

    Boulahroud, Omar; Elasri, Abad; Elmostarchid, Brahim; Boucetta, Mohammed

    2009-01-01

    Intraradicular lumbar disc herniation is a rare complication of disc disease that is generally diagnosed only during surgery. The mechanism for herniated disc penetration into the intradural space is not known with certainty, but adhesion between the radicular dura and the posterior longitudinal ligament was suggested as the most important condition. The authors report the first case of an intraradicular lumbar disc herniation without subdural penetration; the disc hernia was lodged between the two radicular dura layers. The patient, a 34-year-old soldier, was admitted with a 12-month history of low back pain and episodic left sciatica. Neurologic examination showed a positive straight leg raising test on the left side without sensory, motor or sphincter disturbances. Spinal CT scan and MRI exploration revealed a left posterolateral osteophyte formation at the L5–S1 level with an irregular large disc herniation, which migrated superiorly. An intradural extension was suspected. A left L5 hemilaminectomy and S1 foraminotomy were performed. The exploration revealed a large fragment of disc material located between the inner and outer layers of the left S1 radicular dura. The mass was extirpated without cerebrospinal fluid outflow. The postoperative course was uneventful. Radicular interdural lumbar disc herniation should be suspected when a swollen, hard and immobile nerve root is present intraoperatively. PMID:19888608

  3. Closed-Form and Numerically-Stable Solutions to Problems Related to the Optimal Two-Impulse Transfer Between Specified Terminal States of Keplerian Orbits

    Science.gov (United States)

    Senent, Juan

    2011-01-01

    The first part of the paper presents some closed-form solutions to the optimal two-impulse transfer between fixed position and velocity vectors on Keplerian orbits when some constraints are imposed on the magnitude of the initial and final impulses. Additionally, a numerically-stable gradient-free algorithm with guaranteed convergence is presented for the minimum delta-v two-impulse transfer. In the second part of the paper, cooperative bargaining theory is used to solve some two-impulse transfer problems when the initial and final impulses are carried by different vehicles or when the goal is to minimize the delta-v and the time-of-flight at the same time.

  4. The velocity ellipsoid in the Galactic disc using Gaia DR1

    Science.gov (United States)

    Anguiano, Borja; Majewski, Steven R.; Freeman, Kenneth C.; Mitschang, Arik W.; Smith, Martin C.

    2018-02-01

    The stellar velocity ellipsoid of the solar neighbour (d Gaia DR1. We find the average velocity dispersion values for the three space velocity components for the thin and thick discs of (σU, σV, σW)thin = (33 ± 4, 28 ± 2, 23 ± 2) and (σU, σV, σW)thick = (57 ± 6, 38 ± 5, 37 ± 4) km s-1, respectively. The mean values of the ratio between the semi-axes of the velocity ellipsoid for the thin disc are found to be σV/σU = 0.70 ± 0.13 and σW/σU is 0.64 ± 0.08, while for the thick disc σV/σU = 0.67 ± 0.11 and σW/σU is 0.66 ± 0.11. Inputting these dispersions into the linear Strömberg relation for the thin disc groups, we find the Sun's velocity with respect to the Local Standard of Rest in Galactic rotation to be V⊙ = 13.9 ± 3.4 km s-1. A relation is found between the vertex deviation and the chemical abundances for the thin disc, ranging from -5 to +40° as iron abundance increases. For the thick disc we find a vertex deviation of luv ˜- 15°. The tilt angle (luw) in the U-W plane for the thin disc groups ranges from -10 to +15°, but there is no evident relation between luw and the mean abundances. However, we find a weak relation for luw as a function of iron abundances and α-elements for most of the groups in the thick disc, where the tilt angle decreases from -5 to -20° when [Fe/H] decreases and [α/Fe] increases. The velocity anisotropy parameter is independent of the chemical group abundances and its value is nearly constant for both discs (β ˜ 0.5), suggesting that the combined disc is dynamically relaxed.

  5. Elasticplastic discs under plane stress conditions

    CERN Document Server

    Alexandrov, Sergey

    2015-01-01

    This Volume presents a unified approach to calculate the plane stress distribution of stress and strain in thin elastic/plastic discs subject to various loading conditions. There is a vast amount of literature on analytical and semi-analytical solutions for such discs obeying Tresca’s yield criterion and its associated flow rule. On the other hand, most of analytical and semi-analytical solutions for Mises yield criterion are based on the deformation theory of plasticity. A distinguished feature of the solutions given in the present volume is that the flow theory of plasticity and Mises yield criterion are adopted. The solutions are semi-analytical in the sense that numerical methods are only necessary to evaluate ordinary integrals and solve transcendental equations. The book shows that under certain conditions solutions based on the deformation and flow theories of plasticity coincide. All the solutions are illustrated with numerical examples. The goal of the book is to provide the reader with a vision an...

  6. Is the disc thermal state controlling the Blandford & Znajek/Blandford & Payne jet dichotomy?

    Directory of Open Access Journals (Sweden)

    Ferreira Jonathan

    2013-12-01

    Full Text Available It is generally assumed that Blandford & Payne jets can carry a significant fraction of the accretion power released in the underlying disc. But this fraction actually strongly depends on the disc aspect ratio h/r, hence on the disc thermal properties. In fact, Jet Emitting discs (JEDs cannot power BP-like jets if they are thicker than h/r ≃ 0.2. On the other hand, the power of Blandford & Znajek jets depends mostly on the magnitude of the vertical magnetic field Bz. If this magnetic field is dragged in by the accretion flow, then its magnitude depends also on the disc aspect ratio and the BZ jet maximum power is achieved with Magnetically Arrested Discs (MADs. If the innermost disc regions are geometrically thin or slim, they are in a JED state with both BP and BZ jets launched. It is shown that the BZ jet acts only as a highly relativistic and shinning spine, carrying a tiny fraction of the overall jet power. If the innermost disc regions are geometrically thick, they are in a MAD state where only BZ jets are allowed. We expect quite di↵erent jet morphologies in the two cases.

  7. The innate origin of radial and vertical gradients in a simulated galaxy disc

    Science.gov (United States)

    Navarro, Julio F.; Yozin, Cameron; Loewen, Nic; Benítez-Llambay, Alejandro; Fattahi, Azadeh; Frenk, Carlos S.; Oman, Kyle A.; Schaye, Joop; Theuns, Tom

    2018-02-01

    We examine the origin of radial and vertical gradients in the age/metallicity of the stellar component of a galaxy disc formed in the APOSTLE cosmological hydrodynamical simulations. Some of these gradients resemble those in the Milky Way, where they have sometimes been interpreted as due to internal evolution, such as scattering off giant molecular clouds, radial migration driven by spiral patterns, or orbital resonances with a bar. Secular processes play a minor role in the simulated galaxy, which lacks strong spiral or bar patterns, and where such gradients arise as a result of the gradual enrichment of a gaseous disc that is born thick but thins as it turns into stars and settles into centrifugal equilibrium. The settling is controlled by the feedback of young stars; which links the star formation, enrichment, and equilibration timescales, inducing radial and vertical gradients in the gaseous disc and its descendent stars. The kinematics of coeval stars evolve little after birth and provide a faithful snapshot of the gaseous disc structure at the time of their formation. In this interpretation, the age-velocity dispersion relation would reflect the gradual thinning of the disc rather than the importance of secular orbit scattering; the outward flaring of stars would result from the gas disc flare rather than from radial migration; and vertical gradients would arise because the gas disc gradually thinned as it enriched. Such radial and vertical trends might just reflect the evolving properties of the parent gaseous disc, and are not necessarily the result of secular evolutionary processes.

  8. On total disc replacement.

    Science.gov (United States)

    Berg, Svante

    2011-02-01

    Low back pain consumes a large part of the community's resources dedicated to health care and sick leave. Back disorders also negatively affect the individual leading to pain suffering, decreased quality-of-life and disability. Chronic low back pain (CLBP) due to degenerative disc disease (DDD) is today often treated with fusion when conservative treatment has failed and symptoms are severe. This treatment is as successful as arthroplasty is for hip arthritis in restoring the patient's quality of life and reducing disability. Even so, there are some problems with this treatment, one of these being recurrent CLBP from an adjacent segment (ASD) after primarily successful surgery. This has led to the development of alternative surgical treatments and devices that maintain or restore mobility, in order to reduce the risk for ASD. Of these new devices, the most frequently used are the disc prostheses used in Total Disc Replacement (TDR). This thesis is based on four studies comparing total disc replacement with posterior fusion. The studies are all based on a material of 152 patients with DDD in one or two segments, aged 20-55 years that were randomly treated with either posterior fusion or TDR. The first study concerned clinical outcome and complications. Follow-up was 100% at both one and two years. It revealed that both treatment groups had a clear benefit from treatment and that patients with TDR were better in almost all outcome scores at one-year follow-up. Fusion patients continued to improve during the second year. At two-year follow-up there was a remaining difference in favour of TDR for back pain. 73% in the TDR group and 63% in the fusion group were much better or totally pain-free (n.s.), while twice as many patients in the TDR group were totally pain free (30%) compared to the fusion group (15%). Time of surgery and total time in hospital were shorter in the TDR group. There was no difference in complications and reoperations, except that seventeen of the

  9. Comparison of Animal Discs Used in Disc Research to Human Lumbar Disc: Torsion Mechanics and Collagen Content

    Science.gov (United States)

    Showalter, Brent L.; Beckstein, Jesse C.; Martin, John T.; Beattie, Elizabeth E.; Orías, Alejandro A. Espinoza; Schaer, Thomas P.; Vresilovic, Edward J.; Elliott, Dawn M.

    2012-01-01

    Study Design Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these to the human disc. Objective To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. Summary of Background Data There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Methods Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar, and cow, rat, and mouse caudal. Collagen content was measured and normalized by dry weight for the same discs except the rat and mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Results Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Conclusion Disc torsion mechanics are comparable to human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented is useful for selecting and interpreting results for animal models of the disc. Structural composition of the disc, such as initial fiber angle, may explain the differences that were noted between species after geometric normalization. PMID:22333953

  10. Lumbar disc excision through fenestration

    Directory of Open Access Journals (Sweden)

    Sangwan S

    2006-01-01

    Full Text Available Background : Lumbar disc herniation often causes sciatica. Many different techniques have been advocated with the aim of least possible damage to other structures while dealing with prolapsed disc surgically in the properly selected and indicated cases. Methods : Twenty six patients with clinical symptoms and signs of prolapsed lumbar intervertebral disc having radiological correlation by MRI study were subjected to disc excision by interlaminar fenestration method. Results : The assessment at follow-up showed excellent results in 17 patients, good in 6 patients, fair in 2 patients and poor in 1 patient. The mean preoperative and postoperative Visual Analogue Scores were 9.34 ±0.84 and 2.19 ±0.84 on scale of 0-10 respectively. These were statistically significant (p value< 0.001, paired t test. No significant complications were recorded. Conclusion : Procedures of interlaminar fenestration and open disc excision under direct vision offers sufficient adequate exposure for lumbar disc excision with a smaller incision, lesser morbidity, shorter convalescence, early return to work and comparable overall results in the centers where recent laser and endoscopy facilities are not available.

  11. Disc piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power.

  12. On gyroscopic effects in vibrating and axially rotating solid and annular discs

    CSIR Research Space (South Africa)

    Joubert, SV

    2007-05-01

    Full Text Available are negligible. Our model is formulated in general terms and then compared to a formulation in terms of Novozhilov-Arnold-Warbur-ton’s theory of thin shells. The system of equations of motion of the disc is separated and transformed into a pair of wave equations...

  13. Thermal distortion of disc-shaped ductile iron castings in vertically parted moulds

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Rasmussen, Jakob; Tiedje, Niels Skat

    2015-01-01

    A disc-shaped casting with an inner boss and an outer rim, separated by a thin walled section, was examined. This measurable deformation varied with the feeding modulus. The influence of alloy composition, particularly Si content, was examined with a pearlitic ductile iron (EN-GJS-500-7) and a fu...

  14. Experimental investigation of wake evolution behind a couple of flat discs in a hydrochannel

    DEFF Research Database (Denmark)

    Naumov, I.V.; Litvinov, I.V.; Mikkelsen, Robert Flemming

    2016-01-01

    The decay of a far wake and its turbulent fluctuations behind two thin discs of the same diameter D, oriented normal to the incident flow, have been studied using the Particle Image Velocimetry (PIV). The experimental study was carried out in a water flume (Re ≈ 2·105) with varying distances betw...

  15. Dipole-exchange spin waves in perpendicularly magnetized discs: Role of the Oersted field

    Science.gov (United States)

    Arias, R. E.; Mills, D. L.

    2007-06-01

    We develop the theory of the exchange dipole spin waves in thin circular discs for the case where the magnetization is nominally perpendicular to the plane. Our interest is in the circumstance where a transport current is injected into the disc, with current also perpendicular to the plane of the disc. Such a current creates an azimuthal magnetic field, referred to often as the Oersted field. We develop the theory of the influence of the Oersted field on the spin-wave spectrum of the disc. This field produces a vortex state. We suggest that this vortex state is stable down to zero applied field. If the external applied field H0 is in the +z direction, perpendicular to the plane of the disc, the vortex state has magnetization at the center of the disc also parallel to +z always. This is the case even when H0<4πMS , where the magnetization at the center of the disc is antiparallel to the local field H0-4πMS there. We present calculations of the current dependence of spin-wave frequencies of several modes as a function of applied magnetic field. We also address an issue overlooked in previous studies of spin waves in thin discs. This is that for quantitative purposes, it is not sufficient to describe internal dipole fields generated by the spin motions simply by adding an effective internal field -4πmzẑ to the equations of motion, with mz the component of dynamic magnetization normal to the surface. For samples of present interest, we derive terms we call gradient corrections, and these play a role quantitatively comparable to exchange itself in the analysis of the spin-wave frequencies. Quantitative studies of spin dynamics in such samples thus must include the gradient corrections.

  16. Vertebral osteomyelitis without disc involvement

    Energy Technology Data Exchange (ETDEWEB)

    Kamani, I.; Syed, I.; Saifuddin, A. E-mail: asaifuddin@aol.com; Green, R.; MacSweeney, F

    2004-10-01

    Vertebral osteomyelitis is most commonly due to pyogenic or granulomatous infection and typically results in the combined involvement of the intervertebral disc and adjacent vertebral bodies. Non-infective causes include the related conditions of chronic recurrent multifocal osteomyelitis (CRMO) and SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome. Occasionally, these conditions may present purely within the vertebral body, resulting in various combinations of vertebral marrow oedema and sclerosis, destructive lesions of the vertebral body and pathological vertebral collapse, thus mimicking neoplastic disease. This review illustrates the imaging features of vertebral osteomyelitis without disc involvement, with emphasis on magnetic resonance imaging (MRI) findings.

  17. Intervertebral disc degeneration : Studies in the loaded disc culture system

    NARCIS (Netherlands)

    Paul, C.P.L.

    2018-01-01

    In dit proefschrift wordt een model beschreven, het Loaded Disc Culture System (LDCS), voor het ex vivo bestuderen van de effecten van mechanische belasting op de tussenwervelschijf. In hoofdstuk 2 laten we zien dat een zekere dosis aan dagelijkse belasting nodig is om de cellen van de

  18. Dead discs, unstable discs and the stars they surround

    Directory of Open Access Journals (Sweden)

    D’Angelo Caroline

    2014-01-01

    Full Text Available Strong stellar magnetic fields significantly alter the behaviour of surrounding accretion discs. Recent work has demonstrated that at low accretion rates a large amount of mass can remain confined in the disc, contrary to the standard assumption that the magnetic field will expel the disc in an outflow (the “propeller regime”. These “dead discs” often become unstable, causing cycles of accretion onto the central star. Here I present the main predictions of this model, and argue that it provides a good explanation for the peculiar behaviour seen in several accreting sources with strong magnetic fields. I will focus in particular on three accreting millisecond X-ray pulsars: SAX J1808.4-3658, NGC 6440 X-2 and IGR J00291+5934. These sources all show low-frequency quasi-periodic oscillations consistent with a variable accretion rate, as well as unusual outburst patterns that suggest gas is confined in the inner disc regions during quiescence.

  19. Generation of inclined protoplanetary discs and misaligned planets through mass accretion - I. Coplanar secondary discs

    Science.gov (United States)

    Xiang-Gruess, M.; Kroupa, P.

    2017-10-01

    We study the three-dimensional (3D) evolution of a viscous protoplanetary disc that accretes gas material from a second protoplanetary disc during a close encounter in an embedded star cluster. The aim is to investigate the capability of the mass accretion scenario to generate strongly inclined gaseous discs that could later form misaligned planets. We use smoothed particle hydrodynamics to study mass transfer and disc inclination for passing stars and circumstellar discs with different masses. We explore different orbital configurations to find the parameter space that allows significant disc inclination generation. Thies et al. suggested that significant disc inclination and disc or planetary system shrinkage can generally be produced by the accretion of external gas material with a different angular momentum. We found that this condition can be fulfilled for a large range of gas mass and angular momentum. For all encounters, mass accretion from the secondary disc increases with decreasing mass of the secondary proto-star. Thus, higher disc inclinations can be attained for lower secondary stellar masses. Variations of the secondary disc's orientation relative to the orbital plane can alter the disc evolution significantly. The results taken together show that mass accretion can change the 3D disc orientation significantly resulting in strongly inclined discs. In combination with the gravitational interaction between the two star-disc systems, this scenario is relevant for explaining the formation of highly inclined discs that could later form misaligned planets.

  20. Spontaneous regression of an intraspinal disc cyst

    Energy Technology Data Exchange (ETDEWEB)

    Demaerel, P.; Eerens, I.; Wilms, G. [University Hospital, Leuven (Belgium). Dept. of Radiology; Goffin, J. [Dept. of Neurosurgery, University Hospitals, Leuven (Belgium)

    2001-11-01

    We present a patient with a so-called disc cyst. Its location in the ventrolateral epidural space and its communication with the herniated disc are clearly shown. The disc cyst developed rapidly and regressed spontaneously. This observation, which has not been reported until now, appears to support focal degeneration with cyst formation as the pathogenesis. (orig.)

  1. Thermochemical modelling of brown dwarf discs

    NARCIS (Netherlands)

    Greenwood, A. J.; Kamp, I.; Waters, L. B. F. M.; Woitke, P.; Thi, W.-F.; Rab, Ch.; Aresu, G.; Spaans, M.

    The physical properties of brown dwarf discs, in terms of their shapes and sizes, are still largely unexplored by observations. ALMA has by far the best capabilities to observe these discs in sub-mm CO lines and dust continuum, while also spatially resolving some discs. To what extent brown dwarf

  2. 46 CFR 64.61 - Rupture disc.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc...

  3. Novel therapeutic strategies for degenerative disc disease: Review of cell biology and intervertebral disc cell therapy.

    Science.gov (United States)

    Fernandez-Moure, Joseph; Moore, Caitlyn A; Kim, Keemberly; Karim, Azim; Smith, Kevin; Barbosa, Zonia; Van Eps, Jeffrey; Rameshwar, Pranela; Weiner, Bradley

    2018-01-01

    Intervertebral disc degeneration is a disease of the discs connecting adjoining vertebrae in which structural damage leads to loss of disc integrity. Degeneration of the disc can be a normal process of ageing, but can also be precipitated by other factors. Literature has made substantial progress in understanding the biological basis of intervertebral disc, which is reviewed here. Current medical and surgical management strategies have shortcomings that do not lend promise to be effective solutions in the coming years. With advances in understanding the cell biology and characteristics of the intervertebral disc at the molecular and cellular level that have been made, alternative strategies for addressing disc pathology can be discovered. A brief overview of the anatomic, cellular, and molecular structure of the intervertebral disc is provided as well as cellular and molecular pathophysiology surrounding intervertebral disc degeneration. Potential therapeutic strategies involving stem cell, protein, and genetic therapy for intervertebral disc degeneration are further discussed.

  4. EXTREMELY LARGE AND HOT MULTILAYER KEPLERIAN DISK AROUND THE O-TYPE PROTOSTAR W51N: THE PRECURSORS OF THE HCH II REGIONS?

    International Nuclear Information System (INIS)

    Zapata, Luis A.; Tang, Ya-Wen; Leurini, Silvia

    2010-01-01

    We present sensitive high angular resolution (0.''57-0.''78) SO, SO 2 , CO, C 2 H 5 OH, HC 3 N, and HCOCH 2 OH line observations at millimeter and submillimeter wavelengths of the young O-type protostar W51 North made with the Submillimeter Array. We report the presence of a large (about 8000 AU) and hot molecular circumstellar disk around this object, which connects the inner dusty disk with the molecular ring or toroid reported recently and confirms the existence of a single bipolar outflow emanating from this object. The molecular emission from the large disk is observed in layers with the transitions characterized by high excitation temperatures in their lower energy states (up to 1512 K) being concentrated closer to the central massive protostar. The molecular emission from those transitions with low or moderate excitation temperatures is found in the outermost parts of the disk and exhibits an inner cavity with an angular size of around 0.''7. We modeled all lines with a local thermodynamic equilibrium (LTE) synthetic spectrum. A detailed study of the kinematics of the molecular gas together with an LTE model of a circumstellar disk shows that the innermost parts of the disk are also Keplerian plus a contracting velocity. The emission of the HCOCH 2 OH reveals the possible presence of a warm 'companion' located to the northeast of the disk, however its nature is unclear. The emission of the SO and SO 2 is observed in the circumstellar disk as well as in the outflow. We suggest that the massive protostar W51 North appears to be in a phase before the presence of a hypercompact or an ultracompact H II (HC/UCH II) region and propose a possible sequence on the formation of the massive stars.

  5. Extremely Large and Hot Multilayer Keplerian Disk Around the O-type Protostar W51N: The Precursors of the HCH II Regions?

    Science.gov (United States)

    Zapata, Luis A.; Tang, Ya-Wen; Leurini, Silvia

    2010-12-01

    We present sensitive high angular resolution (0farcs57-0farcs78) SO, SO2, CO, C2H5OH, HC3N, and HCOCH2OH line observations at millimeter and submillimeter wavelengths of the young O-type protostar W51 North made with the Submillimeter Array. We report the presence of a large (about 8000 AU) and hot molecular circumstellar disk around this object, which connects the inner dusty disk with the molecular ring or toroid reported recently and confirms the existence of a single bipolar outflow emanating from this object. The molecular emission from the large disk is observed in layers with the transitions characterized by high excitation temperatures in their lower energy states (up to 1512 K) being concentrated closer to the central massive protostar. The molecular emission from those transitions with low or moderate excitation temperatures is found in the outermost parts of the disk and exhibits an inner cavity with an angular size of around 0farcs7. We modeled all lines with a local thermodynamic equilibrium (LTE) synthetic spectrum. A detailed study of the kinematics of the molecular gas together with an LTE model of a circumstellar disk shows that the innermost parts of the disk are also Keplerian plus a contracting velocity. The emission of the HCOCH2OH reveals the possible presence of a warm "companion" located to the northeast of the disk, however its nature is unclear. The emission of the SO and SO2 is observed in the circumstellar disk as well as in the outflow. We suggest that the massive protostar W51 North appears to be in a phase before the presence of a hypercompact or an ultracompact H II (HC/UCH II) region and propose a possible sequence on the formation of the massive stars.

  6. Electromagnetic Levitation of a Disc

    Science.gov (United States)

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  7. Intervertebral disc degeneration in dogs

    NARCIS (Netherlands)

    Bergknut, Niklas

    Back pain is common in both dogs and humans, and is often associated with intervertebral disc (IVD) degeneration. The IVDs are essential structures of the spine and degeneration can ultimately result in diseases such as IVD herniation or spinal instability. In order to design new treatments halting

  8. Intervertebral disc degeneration in dogs

    NARCIS (Netherlands)

    Bergknut, N.|info:eu-repo/dai/nl/314418059

    2011-01-01

    Back pain is common in both dogs and humans, and is often associated with intervertebral disc (IVD) degeneration. The IVDs are essential structures of the spine and degeneration can ultimately result in diseases such as IVD herniation or spinal instability. In order to design new treatments halting

  9. Episodic cauda equina compression from an intradural lumbar herniated disc: a case of 'floppy disc'.

    Science.gov (United States)

    Nagaria, J; Chan, Cc; Kamel, Mh; McEvoy, L; Bolger, C

    2011-09-01

    Intradural disc herniation (IDDH) is a rare complication of intervertebral disc disease and comprises 0.26-0.30% of all herniated discs, with 92% of them located in the lumbar region (1). We present a case of IDDH that presented with intermittent symptoms and signs of cauda equina compression. We were unable to find in the literature, any previously described cases of intermittent cauda equina compression from a herniated intradural disc fragment leading to a "floppy disc syndrome". © JSCR.

  10. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level

    OpenAIRE

    Hakan, Tayfun; G?rcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain ...

  11. MR imaging findings of a sequestered disc in the lumbar spine: a comparison with an extruded disc

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Su Youn; Park, Ji Seon; Ryu, Kyung Nam [Kyung Hee University Medical Center, Seoul (Korea, Republic of); Jin, Wook [Kyung Hee University East-west Neo Medical Center, Seoul (Korea, Republic of)

    2007-10-15

    To compare the MR findings of a sequestered disc with an extruded disc. MR images of 28 patients with a sequestered disc and 18 patients with an extruded disc were retrospectively reviewed. Patients with sequestered discs were divided into two groups whether definite separation from the parent disc was or was not seen. In the latter group (definite separation not seen) and the extruded disc group of patients, the signal intensities of the herniated discs were compared with the signal intensities of the parent discs and were evaluated on T1-and T2-weighted images. We also assessed the presence of a notch within the herniated disc. In the sequestered disc group of patients (28 discs), only 5 discs (18%) showed obvious separation from the parent disc. Among the remaining 23 discs with indefinite separation, the notch was visible in 14 discs (61%) and 9 discs (39%) had no notch. In the extruded disc group (18 discs), the notch was visible in 2 (11%) discs and the difference between the two groups was statistically significant ({rho} 0.0002). The signal intensities of the herniated discs on T1-weighted images were isointense in both the sequestered and extruded discs. The difference of incidence of high signal intensities on T2-weighted images was not statistically significant ({rho} = 0.125). It is necessary to consider the possibility of the presence of a sequestered disc when a herniated disc material shows a notch.

  12. MR imaging findings of a sequestered disc in the lumbar spine: a comparison with an extruded disc

    International Nuclear Information System (INIS)

    Sim, Su Youn; Park, Ji Seon; Ryu, Kyung Nam; Jin, Wook

    2007-01-01

    To compare the MR findings of a sequestered disc with an extruded disc. MR images of 28 patients with a sequestered disc and 18 patients with an extruded disc were retrospectively reviewed. Patients with sequestered discs were divided into two groups whether definite separation from the parent disc was or was not seen. In the latter group (definite separation not seen) and the extruded disc group of patients, the signal intensities of the herniated discs were compared with the signal intensities of the parent discs and were evaluated on T1-and T2-weighted images. We also assessed the presence of a notch within the herniated disc. In the sequestered disc group of patients (28 discs), only 5 discs (18%) showed obvious separation from the parent disc. Among the remaining 23 discs with indefinite separation, the notch was visible in 14 discs (61%) and 9 discs (39%) had no notch. In the extruded disc group (18 discs), the notch was visible in 2 (11%) discs and the difference between the two groups was statistically significant (ρ 0.0002). The signal intensities of the herniated discs on T1-weighted images were isointense in both the sequestered and extruded discs. The difference of incidence of high signal intensities on T2-weighted images was not statistically significant (ρ = 0.125). It is necessary to consider the possibility of the presence of a sequestered disc when a herniated disc material shows a notch

  13. Intervertebral disc calcifications in children.

    Science.gov (United States)

    Beluffi, G; Fiori, P; Sileo, C

    2009-03-01

    This study was done to assess the presence of both asymptomatic and symptomatic intervertebral disc calcifications in a large paediatric population. We retrospectively reviewed the radiographs taken during the past 26 years in children (age 0-18 years) undergoing imaging of the spine or of other body segments in which the spine was adequately depicted, to determine possible intervertebral disc calcifications. The following clinical evaluation was extrapolated from the patients' charts: presence of spinal symptoms, history of trauma, suspected or clinically evident scoliosis, suspected or clinically evident syndromes, bone dysplasias, and pre- or postoperative chest or abdominal X-rays. We detected intervertebral disc calcifications in six patients only. Five calcifications were asymptomatic (one newborn baby with Patau syndrome; three patients studied to rule out scoliosis, hypochondroplasia and syndromic traits; one for dyspnoea due to sunflower seeds inhalation). Only one was symptomatic, with acute neck pain. Calcifications varied in number from one in one patient to two to five in the others. Apart from the calcification in the patient with cervical pain, all calcifications were asymptomatic and constituted an incidental finding (particularly those detected at the thoracic level in the patient studied for sunflower-seed inhalation). Calcification shapes were either linear or round. Our series confirms that intervertebral disc calcifications are a rare finding in childhood and should not be a source of concern: symptomatic calcifications tend to regress spontaneously within a short time with or without therapy and immobilisation, whereas asymptomatic calcifications may last for years but disappear before the age of 20 years. Only very few cases, such as those of medullary compression or severe dysphagia due to anterior herniation of cervical discs, may require surgical procedures.

  14. Disc degeneration: current surgical options

    Directory of Open Access Journals (Sweden)

    C Schizas

    2010-10-01

    Full Text Available Chronic low back pain attributed to lumbar disc degeneration poses a serious challenge to physicians. Surgery may be indicated in selected cases following failure of appropriate conservative treatment. For decades, the only surgical option has been spinal fusion, but its results have been inconsistent. Some prospective trials show superiority over usual conservative measures while others fail to demonstrate its advantages. In an effort to improve results of fusion and to decrease the incidence of adjacent segment degeneration, total disc replacement techniques have been introduced and studied extensively. Short-term results have shown superiority over some fusion techniques. Mid-term results however tend to show that this approach yields results equivalent to those of spinal fusion. Nucleus replacement has gained some popularity initially, but evidence on its efficacy is scarce. Dynamic stabilisation, a technique involving less rigid implants than in spinal fusion and performed without the need for bone grafting, represents another surgical option. Evidence again is lacking on its superiority over other surgical strategies and conservative measures. Insertion of interspinous devices posteriorly, aiming at redistributing loads and relieving pain, has been used as an adjunct to disc removal surgery for disc herniation. To date however, there is no clear evidence on their efficacy. Minimally invasive intradiscal thermocoagulation techniques have also been tried, but evidence of their effectiveness is questioned. Surgery using novel biological solutions may be the future of discogenic pain treatment. Collaboration between clinicians and basic scientists in this multidisciplinary field will undoubtedly shape the future of treating symptomatic disc degeneration.

  15. The temporal evolution of neutron-capture elements in the Galactic discs

    Science.gov (United States)

    Spina, Lorenzo; Meléndez, Jorge; Karakas, Amanda I.; dos Santos, Leonardo; Bedell, Megan; Asplund, Martin; Ramírez, Ivan; Yong, David; Alves-Brito, Alan; Bean, Jacob L.; Dreizler, Stefan

    2018-02-01

    Important insights into the formation and evolution of the Galactic disc(s) are contained in the chemical compositions of stars. We analysed high-resolution and high signal-to-noise HARPS spectra of 79 solar twin stars in order to obtain precise determinations of their atmospheric parameters, ages (σ ˜0.4 Gyr) and chemical abundances (σ Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd and Dy). This valuable data set allows us to study the [X/Fe]-age relations over a time interval of ˜10 Gyr and among stars belonging to the thin and thick discs. These relations show that (i) the s-process has been the main channel of nucleosynthesis of n-capture elements during the evolution of the thin disc; (ii) the thick disc is rich in r-process elements which suggests that its formation has been rapid and intensive. In addition, the heavy (Ba, La, Ce) and light (Sr, Y, Zr) s-process elements revealed details on the dependence between the yields of AGB stars and the stellar mass or metallicity. Finally, we confirmed that both [Y/Mg] and [Y/Al] ratios can be employed as stellar clocks, allowing ages of solar twin stars to be estimated with an average precision of ˜0.5 Gyr.

  16. CT findings of lumbar intervertebral disc: II. Disc herniation (HNP)

    International Nuclear Information System (INIS)

    Yang, W. J.; Lee, J. M.; Bahk, Y. W.

    1984-01-01

    In lumbar region the epidural fat pad is relatively abundant so that CT can provides sufficient information in diagnosis of lumbar HNP. Many authors have reported on the CT findings of HNP such as focal nodular protrusion of the posterior disc margin, obliteration of epidural fat pad, impingement of dural sac and nerve root, swelling of nerve root, soft tissue density in the spinal canal and calcification of disc. However there was so previous report describing incidence and reliability of the findings. It is the purpose of the present study to survey the frequency, reliability, and limitation of these CT findings. The clinical material was consisted of 30 operatively proven cases of HNP of the lumbar spine. Each lumbar CT scan was reviewed retrospectively and the findings were analysed by two radiologists independently. There were 20 males and 10 females and the mean age was 36.7 years. Involvement of L4-S5 level was 2.3 times more frequent than that of L5-S1 level. Of 30 cases, 22 were unilateral posterolateral types and 8 cases central or unilateral far lateral types. CT findings observed were nodular protrusion of the posterior margin of the disc, obliteration of epidural fat pad, impingement of dural sac or nerve root, soft tissue density in the spinal canal and calcification in the posterior portion of the protruded disc, in order of decreasing frequency. The conclusions are follows: 1. Nodular protrusion of the posterior disc margin accompanied by obliteration of epidural fat pad was observed in every case. The former findings was designated as direct sign and the latter indirect. 2. Obliteration of the epidural fat appears to be significant in lateral recesses especially when it occurs unilaterally. This was not true, however, in the centrally located fat pad. 3. Impingement of the dural sac and nerve root were observed in 90% and 67%, respectively, and were very helpful in establishing HNP diagnosis when the direct and indirect signs were equivocal

  17. The age-velocity dispersion relation of the Galactic discs from LAMOST-Gaia data

    Science.gov (United States)

    Yu, Jincheng; Liu, Chao

    2018-03-01

    We present the age-velocity dispersion relation (AVR) in three dimensions in the solar neighbourhood using 3564 commonly observed sub-giant/red giant branch stars selected from The Large Sky Area Multi-Object Fiber Spectroscopic Telescope, which gives the age and radial velocity, and Gaia, which measures the distance and proper motion. The stars are separated into metal-poor ([Fe/H] -0.2 dex) groups, so that the metal-rich stars are mostly α-poor, while the metal-poor group are mostly contributed by α-enhanced stars. Thus, the old and metal-poor stars likely belong to the chemically defined thick disc population, while the metal-rich sample is dominated by the thin disc. The AVR for the metal-poor sample shows an abrupt increase at ≳7 Gyr, which is contributed by the thick disc component. On the other hand, most of the thin disc stars with [Fe/H] > -0.2 dex display a power-law-like AVR with indices of about 0.3-0.4 and 0.5 for the in-plane and vertical dispersions, respectively. This is consistent with the scenario that the disc is gradually heated by the spiral arms and/or the giant molecular clouds. Moreover, the older thin disc stars (>7 Gyr) have a rounder velocity ellipsoid, i.e. σϕ/σz is close to 1.0, probably due to the more efficient heating in vertical direction. Particularly for the old metal-poor sample located with |z| > 270 pc, the vertical dispersion is even larger than its azimuthal counterpart. Finally, the vertex deviations and the tilt angles are plausibly around zero with large uncertainties.

  18. Factors that influence recurrent lumbar disc herniation.

    Science.gov (United States)

    Yaman, M E; Kazancı, A; Yaman, N D; Baş, F; Ayberk, G

    2017-06-01

    The most common cause of poor outcome following lumbar disc surgery is recurrent herniation. Recurrence has been noted in 5% to 15% of patients with surgically treated primary lumbar disc herniation. There have been many studies designed to determine the risk factors for recurrent lumbar disc herniation. In this study, we retrospectively analysed the influence of disc degeneration, endplate changes, surgical technique, and patient's clinical characteristics on recurrent lumbar disc herniation. Patients who underwent primary single-level L4-L5 lumbar discectomy and who were reoperated on for recurrent L4-L5 disc herniation were retrospectively reviewed. All these operations were performed between August 2004 and September 2009 at the Neurosurgery Department of Ataturk Education and Research Hospital in Ankara, Turkey. During the study period, 126 patients were reviewed, with 101 patients underwent primary single-level L4-L5 lumbar discectomy and 25 patients were reoperated on for recurrent L4-L5 disc herniation. Preoperative higher intervertebral disc height (Pdisc herniation had preoperative higher disc height and higher body mass index. Modic endplate changes had a higher tendency for recurrence of lumbar disc herniation. Well-planned and well-conducted large-scale prospective cohort studies are needed to confirm this and enable convenient treatment modalities to prevent recurrent disc pathology.

  19. Three-level cervical disc herniation

    Directory of Open Access Journals (Sweden)

    St. Iencean Andrei

    2015-09-01

    Full Text Available Multilevel cervical degenerative disc disease is well known in the cervical spine pathology, with radicular syndromes or cervical myelopathy. One or two level cervical herniated disc is common in adult and multilevel cervical degenerative disc herniation is common in the elderly, with spinal stenosis, and have the same cause: the gradual degeneration of the disc. We report the case of a patient with two level cervical disc herniation (C4 – C5 and C5 – C6 treated by anterior cervical microdiscectomy both levels and fusion at C5 – C6; after five years the patient returned with left C7 radiculopathy and MRI provided the image of a left C6 – C7 disc herniation, he underwent an anterior microsurgical discectomy with rapid relief of symptoms. Three-level cervical herniated disc are rare in adults, and the anterior microdiscectomy with or without fusion solve this pathology.

  20. Migrated herniated disc mimicking a neoplasm.

    Science.gov (United States)

    Hoch, Benjamin; Hermann, George

    2010-12-01

    Disc sequestration is defined as migration of a herniated disc fragment into the epidural space such that it is completely separated from the parent disc. We report a case of a migrated herniated disc that was initially pathologically diagnosed as a cartilage neoplasm. In addition to confounding morphological features, this interpretation may have been influenced by an initial radiological interpretation that did not include herniated disc in the differential diagnosis of a spinal lesion with prominent peripheral contrast enhancement. MR imaging is most helpful in considering other lesions in the differential diagnosis including abscess, hematoma, and primary or metastatic neoplasms. Pathologically, degenerative changes in herniated discs, including clustering of chondrocytes and neovascularization, may be severe resulting in a pseudoneoplastic appearance. Increased awareness of the radiological and pathological features of migrated herniated disc should limit confusion with other tumors.

  1. Retina image–based optic disc segmentation

    Directory of Open Access Journals (Sweden)

    Ching-Lin Wang

    2016-05-01

    Full Text Available The change of optic disc can be used to diagnose many eye diseases, such as glaucoma, diabetic retinopathy and macular degeneration. Moreover, retinal blood vessel pattern is unique for human beings even for identical twins. It is a highly stable pattern in biometric identification. Since optic disc is the beginning of the optic nerve and main blood vessels in retina, it can be used as a reference point of identification. Therefore, optic disc segmentation is an important technique for developing a human identity recognition system and eye disease diagnostic system. This article hence presents an optic disc segmentation method to extract the optic disc from a retina image. The experimental results show that the optic disc segmentation method can give impressive results in segmenting the optic disc from a retina image.

  2. Gravitating discs around black holes

    Czech Academy of Sciences Publication Activity Database

    Karas, Vladimír; Huré, J.-M.; Semerák, O.

    2004-01-01

    Roč. 21, č. 7 (2004), R1-R5 ISSN 0264-9381 R&D Projects: GA ČR GA205/03/0902; GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1003909 Keywords : black holes * accretion discs * general relativity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.941, year: 2004

  3. The PANDA Endcap Disc DIRC

    Science.gov (United States)

    Föhl, K.; Ali, A.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Böhm, M.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Düren, M.; Etzelmüller, E.; Hayrapetyan, A.; Kreutzfeld, K.; Merle, O.; Rieke, J.; Schmidt, M.; Wasem, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

    2018-02-01

    Positively identifying charged kaons in the PANDA forward endcap solid angle range can be achieved with the Endcap Disc DIRC, allowing kaon-pion separation from 1 up to 4 GeV/c with a separation power of at least 3 standard deviations. Design, performance, and components of this DIRC are given, including the recently introduced TOFPET-ASIC based read-out. Results of a prototype operated in a test beam at DESY in 2016 are shown.

  4. Post-Keplerian perturbations of the orbital time shift in binary pulsars: an analytical formulation with applications to the galactic center

    Energy Technology Data Exchange (ETDEWEB)

    Iorio, Lorenzo [Ministero dell' Istruzione, Univ. Ricerca (M.I.U.R.)-Istruzione, Bari (Italy)

    2017-07-15

    We develop a general approach to analytically calculate the perturbations Δδτ p of the orbital component of the change δτ{sub p} of the times of arrival of the pulses emitted by a binary pulsar p induced by the post-Keplerian accelerations due to the mass quadrupole Q{sub 2}, and the post-Newtonian gravitoelectric (GE) and Lense-Thirring (LT) fields. We apply our results to the so-far still hypothetical scenario involving a pulsar orbiting the supermassive black hole in the galactic center at Sgr A*. We also evaluate the gravitomagnetic and quadrupolar Shapiro-like propagation delays δτ{sub prop}. By assuming the orbit of the existing main sequence star S2 and a time span as long as its orbital period P{sub b}, we obtain vertical stroke Δδτ{sub p}{sup GE} vertical stroke

  5. Optic Disc Identification Methods for Retinal Images

    Directory of Open Access Journals (Sweden)

    Florin Rotaru

    2014-07-01

    Full Text Available Presented are the methods proposed by authors to identify and model the optic disc in colour retinal images. The first three our approaches localized the optic disc in two steps: a in the green component of RGB image the optic disc area is detected based on texture indicators and pixel intensity variance analysis; b on the segmented area the optic disc edges are extracted and the resulted boundary is approximated by a Hough transform. The last implemented method identifies the optic disc area by analysis of blood vessels network extracted in the green channel of the original image. In the segmented area the optic disc edges are obtained by an iterative Canny algorithm and are approximated by a circle Hough transform.

  6. Biomaterials for intervertebral disc regeneration and repair.

    Science.gov (United States)

    Bowles, Robert D; Setton, Lori A

    2017-06-01

    The intervertebral disc contributes to motion, weight bearing, and flexibility of the spine, but is susceptible to damage and morphological changes that contribute to pathology with age and injury. Engineering strategies that rely upon synthetic materials or composite implants that do not interface with the biological components of the disc have not met with widespread use or desirable outcomes in the treatment of intervertebral disc pathology. Here we review bioengineering advances to treat disc disorders, using cell-supplemented materials, or acellular, biologically based materials, that provide opportunity for cell-material interactions and remodeling in the treatment of intervertebral disc disorders. While a field still in early development, bioengineering-based strategies employing novel biomaterials are emerging as promising alternatives for clinical treatment of intervertebral disc disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Measurement of activity distribution in an Am-241 disc source using peeled-off Gafchromic EBT3 films.

    Science.gov (United States)

    Lee, Kwang-Ho; Shin, Ji-Yong; Kim, Eun-Hee

    2018-05-01

    Commercial alpha-emitting sources are fabricated mainly in a disc type. An alpha particle irradiator in Radiation Bioengineering Laboratory at Seoul National University was installed with an Am-241 disc source. Commercial Am-241 disc sources are fabricated by incorporating the radioactive element into a thin substrate layer. Those disc sources are utilized assuming that the radioactive element is uniformly distributed in the active layer of disc sources. In this study, we employed peeled-off Gafchromic EBT3 films to investigate the uniformity of areal radioactivity density over the disc source and to measure the effect of non-uniform activity distribution on dose distribution at the bottom of the cell culture dish positioned in a varying distance from the source. The measurements with the peeled-off EBT3 films informed that the areal activity density in the disc source differed by up to approximately 45% from the average. However, the inhomogeneous Am-241 distribution in a disc source did not affect the radial distribution of fluence rate at the inner bottom of cell dish when the dish is apart from the source sufficiently. The dose distribution measured with an EBT3 film nearly accorded with that obtained by Monte Carlo simulation assuming the uniform Am-241 activity distribution in the active layer of the disc source. Finally, the dose to a single-cell layer of 5 μm in a nominal thickness was obtained by Monte Carlo simulation assuming a uniform Am-241 activity distribution in the disc source at distances of 20 and 30 mm from the source. The cellular dose estimates were higher than the film dose estimates at all radial distances. The cellular dose decreased with an increasing radial distance from the center to a smaller extent than the EBT3 film dose did. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Eccentricity evolution during planet-disc interaction

    Science.gov (United States)

    Ragusa, Enrico; Rosotti, Giovanni; Teyssandier, Jean; Booth, Richard; Clarke, Cathie J.; Lodato, Giuseppe

    2018-03-01

    During the process of planet formation, the planet-disc interactions might excite (or damp) the orbital eccentricity of the planet. In this paper, we present two long (t ˜ 3 × 105 orbits) numerical simulations: (a) one (with a relatively light disc, Md/Mp = 0.2), where the eccentricity initially stalls before growing at later times and (b) one (with a more massive disc, Md/Mp = 0.65) with fast growth and a late decrease of the eccentricity. We recover the well-known result that a more massive disc promotes a faster initial growth of the planet eccentricity. However, at late times the planet eccentricity decreases in the massive disc case, but increases in the light disc case. Both simulations show periodic eccentricity oscillations superimposed on a growing/decreasing trend and a rapid transition between fast and slow pericentre precession. The peculiar and contrasting evolution of the eccentricity of both planet and disc in the two simulations can be understood by invoking a simple toy model where the disc is treated as a second point-like gravitating body, subject to secular planet-planet interaction and eccentricity pumping/damping provided by the disc. We show how the counterintuitive result that the more massive simulation produces a lower planet eccentricity at late times can be understood in terms of the different ratios of the disc-to-planet angular momentum in the two simulations. In our interpretation, at late times the planet eccentricity can increase more in low-mass discs rather than in high-mass discs, contrary to previous claims in the literature.

  9. Intradural cervical disc herniation: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Seung Eun; Lee, Sang Ho; Jo, Byung June; Yoon, Deug Hee [Wooridul Spine Hospital, Seoul (Korea, Republic of); Kim, Tae Hong [Inje University College of Medicine, Inje (Korea, Republic of)

    2005-07-15

    Intradural cervical disc herniation is an extremely rare condition and its pathogenesis is not certain. We experienced a case of intradural cervical disc herniation at the C4-5 level in a 56-year-old man. The preoperative sagittal T1- and T2- weighted images revealed an intradural iso-intensity lesion, with the spinal cord behind the posterior longitudinal ligament at the C4-5 disc level. The post-contrast T1-weighted image revealed a peripheral enhanced intradural lesion. We report here on a case of an intradural cervical disc herniation that was diagnosed by radiological examination, and we include a review of the related literature.

  10. Computed tomography in lumbar herniated disc

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chul Soon; Chang, Kee Hyun; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1984-09-15

    197 spine CTs were performed from 29th , March 1982 to 7th March, 1984. Among them, 39 patients preoperatively diagnosed as herniated nucleus pulposus or bulging disc with CT and myelography were operated. 43 disc spaces of disc disease are analysed in true positive and false negative cases. Finally the accuracy, sensitivity and specificity of spine CT and myelography are calculated. The results are as follows: 1. The CT findings of disc diseases are in order of frequency, asymmetrical obliteration of epidural fat (82%) , ventral indentation or compression on dural sac (72%), focal protrusion of disc (64%), root changes - obliteration, displacement, compression, non-filling of metrizamide - (54%), diffuse disc bulging (36%), disc at body level (31%), disc calcifications (26%), disc vacuum (10%) and other associated findings - spinal stenosis, foraminal stenosis, ligament flavum thickening, facet joint hypertrophy (26%). 2. Sensitivities of spine CT and myelography are 95% and 94%, specificities are 67%, 50% and overall accuracies 93%, 87%, respectively. 3. Therefore, it is recommended that the spine CT be used as a primary diagnostic method and the myelography as a secondary complementary study when the CT gives no conclusive findings.

  11. Debris disc constraints on planetesimal formation

    Science.gov (United States)

    Krivov, Alexander V.; Ide, Aljoscha; Löhne, Torsten; Johansen, Anders; Blum, Jürgen

    2018-02-01

    Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical `slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentration models - provided the objects are loosely bound `pebble piles' as these models also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a `disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ˜1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.

  12. Total Disc Replacement in Lumbar Degenerative Disc Diseases.

    Science.gov (United States)

    Park, Chun Kun

    2015-11-01

    More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above.

  13. Total Disc Arthroplasty for Treating Lumbar Degenerative Disc Disease

    Science.gov (United States)

    2015-01-01

    Study Design Lumber disc arthroplasty is a technological advancement that has occurred in the last decade to treat lumbar degenerative disk diseases. Purpose The aim of this retrospective study was to establish the impact and outcomes of managing patients with lumbar degenerative disk disease who have been treated with lumbar total disc arthroplasty (TDA). Overview of Literature Several studies have shown promising results following this surgery. Methods We reviewed the files of 104 patients at the Department of Neurosurgery in Colmar (France) who had been operated on by lumbar spine arthroplasty (Prodisc) between April 2002 and October 2008. Results Among the 104 patients, 67 were female and 37 were male with an average age of 33.1 years. We followed the cases for a mean of 20 months. The most frequent level of discopathy was L4-L5 with 62 patients (59.6%) followed by L5-S1 level with 52 patients (50%). Eighty-three patients suffered from low back pain, 21 of which were associated with radiculopathy. The status of 82 patients improved after surgery according to the Oswestry Disability Index score, and 92 patients returned to work. Conclusions The results indicate that TDA is a good alternative treatment for lumbar spine disk disease, particularly for patients with disabling and chronic low back pain. This technique contributes to improve living conditions with correct patient selection for surgery. PMID:25705336

  14. Filamin actin-binding and titin-binding fulfill distinct functions in Z-disc cohesion.

    Directory of Open Access Journals (Sweden)

    Nicanor González-Morales

    2017-07-01

    Full Text Available Many proteins contribute to the contractile properties of muscles, most notably myosin thick filaments, which are anchored at the M-line, and actin thin filaments, which are anchored at the Z-discs that border each sarcomere. In humans, mutations in the actin-binding protein Filamin-C result in myopathies, but the underlying molecular function is not well understood. Here we show using Drosophila indirect flight muscle that the filamin ortholog Cheerio in conjunction with the giant elastic protein titin plays a crucial role in keeping thin filaments stably anchored at the Z-disc. We identify the filamin domains required for interaction with the titin ortholog Sallimus, and we demonstrate a genetic interaction of filamin with titin and actin. Filamin mutants disrupting the actin- or the titin-binding domain display distinct phenotypes, with Z-discs breaking up in parallel or perpendicularly to the myofibril, respectively. Thus, Z-discs require filamin to withstand the strong contractile forces acting on them.

  15. Use NASA GES DISC Data in ArcGIS

    Science.gov (United States)

    Yang, Wenli; Pham, Long B.; Kempler, Steve

    2015-01-01

    This presentation describes GIS relevant data at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), GES DISC Services and Support for GIS Users, and use cases of GES DISC data in ArcGIS.

  16. Minimum weight design of inhomogeneous rotating discs

    International Nuclear Information System (INIS)

    Jahed, Hamid; Farshi, Behrooz; Bidabadi, Jalal

    2005-01-01

    There are numerous applications for gas turbine discs in the aerospace industry such as in turbojet engines. These discs normally work under high temperatures while subjected to high angular velocities. Minimizing the weight of such items in aerospace applications results in benefits such as low dead weights and lower costs. High speed of rotation causes large centrifugal forces in a disc and simultaneous application of high temperatures reduces disc material strength. Thus, the latter effects tend to increase deformations of the disc under the applied loads. In order to obtain a reliable disc analysis and arrive at the corresponding correct stress distribution, solutions should consider changes in material properties due to the temperature field throughout the disc. To achieve this goal, an inhomogeneous disc model with variable thickness is considered. Using the variable material properties method, stresses are obtained for the disc under rotation and a steady temperature field. In this paper this is done by modelling the rotating disc as a series of rings of different but constant properties. The optimum disc profile is arrived at by sequentially proportioning the thicknesses of each ring to satisfy the stress requirements. This method vis-a-vis a mathematical programming procedure for optimization shows several advantages. Firstly, it is simple iterative proportioning in each design cycle not requiring involved mathematical operations. Secondly, due to its simplicity it alleviates the necessity of certain simplifications that are common in so-called rigorous mathematical procedures. The results obtained, compared to those published in the literature show agreement and superiority. A further advantage of the proposed method is the independence of the end results from the initially assumed point in the iterative design routine, unlike most methods published so far

  17. Quasi-periodic oscillations and the global modes of relativistic, MHD accretion discs

    Science.gov (United States)

    Dewberry, Janosz W.; Latter, Henrik N.; Ogilvie, Gordon I.

    2018-02-01

    The high-frequency quasi-periodic oscillations (HFQPOs) that punctuate the light curves of X-ray binary systems present a window onto the intrinsic properties of stellar-mass black holes and hence a testbed for general relativity. One explanation for these features is that relativistic distortion of the accretion disc's differential rotation creates a trapping region in which inertial waves (r-modes) might grow to observable amplitudes. Local analyses, however, predict that large-scale magnetic fields push this trapping region to the inner disc edge, where conditions may be unfavorable for r-mode growth. We revisit this problem from a pseudo-Newtonian but fully global perspective, deriving linearized equations describing a relativistic, magnetized accretion flow, and calculating normal modes with and without vertical density stratification. In an unstratified model, the choice of vertical wavenumber determines the extent to which vertical magnetic fields drive the r-modes toward the inner edge. In a global model fully incorporating density stratification, we confirm that this susceptibility to magnetic fields depends on disc thickness. Our calculations suggest that in thin discs, r-modes may remain independent of the inner disc edge for vertical magnetic fields with plasma betas as low as β ≈ 100 - 300. We posit that the appearance of r-modes in observations may be more determined by a competition between excitation and damping mechanisms near the ISCO than the modification of the trapping region by magnetic fields.

  18. Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings

    Science.gov (United States)

    Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa

    2004-09-01

    The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.

  19. Thoracic disc herniation: Surgical treatment.

    Science.gov (United States)

    Court, C; Mansour, E; Bouthors, C

    2018-02-01

    Thoracic disc herniation is rare and mainly occurs between T8 and L1. The herniation is calcified in 40% of cases and is labeled as giant when it occupies more than 40% of the spinal canal. A surgical procedure is indicated when the patient has severe back pain, stubborn intercostal neuralgia or neurological deficits. Selection of the surgical approach is essential. Mid-line calcified hernias are approached from a transthoracic incision, while lateralized soft hernias can be approached from a posterolateral incision. The complication rate for transthoracic approaches is higher than that of posterolateral approaches; however, the former are performed in more complex herniation cases. The thoracoscopic approach is less invasive but has a lengthy learning curve. Retropleural mini-thoracotomy is a potential compromise solution. Fusion is recommended in cases of multilevel herniation, herniation in the context of Scheuermann's disease, when more than 50% bone is resected from the vertebral body, in patients with preoperative back pain or herniation at the thoracolumbar junction. Along with complications specific to the surgical approach, the surgical risks are neurological worsening, dural breach and subarachnoid-pleural fistulas. Giant calcified herniated discs are the largest contributor to myelopathy, intradural extension and postoperative complications. Some of the technical means that can be used to prevent complications are explored, along with how to address these complications. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Optic Disc Drusen in Children

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; Li, Xiao Qiang; Eckmann, Christina L

    2017-01-01

    diameter and fetal birth and pubertal parameters are associated with the presence of ODD. METHODS: This observational, longitudinal population-based birth cohort study, with a nested case-control, included 1,406 children. Eye examinations were performed when the children were between 11 and 12 years of age....... Assessment was performed of optical coherence tomography (OCT) scans from 1,304 children with gradable enhanced depth imaging scans of the optic disc. RESULTS: ODD in one or both eyes were found in 13 (1.0%) of all children. All but one of the cases were found in children with scleral canal diameter...... in the lowest quartile (1,182-1,399 μm) in the nested case-control study. Children with ODD had a mean disc diameter of 1,339 μm (interquartile range, 30 μm), whereas it was 1,508 μm (interquartile range, 196 μm) in the 130 controls without ODD (P

  1. Cervical disc hernia operations through posterior laminoforaminotomy

    OpenAIRE

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients ...

  2. Computing Decoupled Residuals for Compact Disc Players

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

    2006-01-01

    In order to improve Compact Disc Players playability regarding playing Compact Discs with surface faults, like scratches and fingerprints etc, the attention has been put on fault tolerant control schemes. Almost every of those methods are based on fault detection. The standard approach is to use...

  3. Genetic association studies in lumbar disc degeneration

    DEFF Research Database (Denmark)

    Eskola, Pasi J; Lemmelä, Susanna; Kjaer, Per

    2012-01-01

    Low back pain is associated with lumbar disc degeneration, which is mainly due to genetic predisposition. The objective of this study was to perform a systematic review to evaluate genetic association studies in lumbar disc degeneration as defined on magnetic resonance imaging (MRI) in humans....

  4. The Actual Level of Symptomatic Soft Disc Herniation in Patients with Cervical Disc Herniation.

    Science.gov (United States)

    Choi, Su Yong; Lee, Sang Gu; Kim, Woo Kyung; Son, Seong; Jeong, Tae Seok

    2015-09-01

    The aim of this study was to predict the relationship between the symptomatic disc herniation level and the osteophyte level or decreased disc height in patients with cervical disc herniation. Between January 2011 and December 2012, 69 patients with an osteophyte of the cervical spine underwent surgery at a single center due to soft cervical disc herniation. Data including soft disc herniation level, osteophyte level in the posterior vertebral margin, Cobb's angle, and symptom duration were retrospectively assessed. The patients were divided into three groups according to the relationship between the degenerative change level and the level of reported symptoms. Among the 69 patients, 48 (69.6%) showed a match between osteophyte level and soft disc herniation level. Disc herniation occurred at the adjacent segment to degenerative osteophyte level in 12 patients (17.4%) and at both the adjacent and the osteophyte level in nine (13.0%). There was no significant difference in Cobb's angle or duration among the three groups. Osteophyte type was not significant. The mean disc height of the prominent degenerative change level group was lower than the adjacent segment level, but this was not significant. Soft cervical disc herniation usually occurs at the level an osteophyte forms. However, it may also occur at segments adjacent to that of the osteophyte level. Therefore, in patients with cervical disc herniation, although a prominent osteophyte alone may appear on plain radiography, we must suspect the presence of soft disc herniation at other levels.

  5. Regression of a symptomatic thoracic disc herniation with a calcified intervertebral disc component

    Directory of Open Access Journals (Sweden)

    Hidayet Sari

    2016-12-01

    Full Text Available There were only a few cases describing spontaneous regression of calcified thoracic disc herniation in the literature. We present a 38-year-old male office worker who had left paramedian-foraminal extruded disc at T7–T8 with calcifications of the T7–T8 and T8–T9 intervertebral discs. This case was unique in that the non-calcified extruded disc material regressed almost completely in 5 months while the calcified intervertebral discs remained the same during the process of regression. This report stresses that regression of the herniated material of the thoracic discs with subsidence of the symptoms is still possible even if the disc material is calcified.

  6. Lumbar disc cyst with contralateral radiculopathy

    Directory of Open Access Journals (Sweden)

    Kishore Tourani

    2012-08-01

    Full Text Available Disc cysts are uncommon intraspinal cystic lesions located in the ventrolateral epidural space. They communicate with the nucleus pulposus of the intervertebral disc and cause symptoms by radicular compression. We report a unique case of lumbar disc cyst that was associated with disc herniation and contralateral radiculopathy. A 22 year old male presented with one month history of back-ache radiating to the left leg. Magnetic Resonance Imaging (MRI showed L3-L4 disc herniation with annular tear and cystic lesion in the extradural space anterior to the thecal sac on right side, which increased in size over a period of 3 weeks. L3 laminectomy and bilateral discectomy and cyst excision was done with partial improvement of patients symptoms.

  7. Spontaneous Regression of Lumbar Herniated Disc

    Directory of Open Access Journals (Sweden)

    Chun-Wei Chang

    2009-12-01

    Full Text Available Intervertebral disc herniation of the lumbar spine is a common disease presenting with low back pain and involving nerve root radiculopathy. Some neurological symptoms in the majority of patients frequently improve after a period of conservative treatment. This has been regarded as the result of a decrease of pressure exerted from the herniated disc on neighboring neurostructures and a gradual regression of inflammation. Recently, with advances in magnetic resonance imaging, many reports have demonstrated that the herniated disc has the potential for spontaneous regression. Regression coincided with the improvement of associated symptoms. However, the exact regression mechanism remains unclear. Here, we present 2 cases of lumbar intervertebral disc herniation with spontaneous regression. We review the literature and discuss the possible mechanisms, the precipitating factors of spontaneous disc regression and the proper timing of surgical intervention.

  8. Magnetic resonance imaging of intervertebral disc degeneration

    International Nuclear Information System (INIS)

    Maeda, Hiroshi; Noguchi, Masao; Kira, Hideaki; Fujiki, Hiroshi; Shimokawa, Isao; Hinoue, Kaichi.

    1993-01-01

    The aim of this study was to correlate the degree of lumbar intervertebral disc degeneration with findings of magnetic resonance imaging (MRI). Seventeen autopsied (from 7 patients) and 21 surgical (from 20 patients) intervertebral discs were used as specimens for histopathological examination. In addition, 21 intervertebral discs were examined on T2-weighted images. Histopathological findings from both autopsied and surgical specimens were well correlated with MRI findings. In particular, T2-weighted images reflected increased collagen fibers and rupture within the fibrous ring accurately. However, when severely degenerated intervertebral discs and hernia protruding the posterior longitudinal ligament existed, histological findings were not concordant well with T2-weighted images. Morphological appearances of autopsy specimens, divided into four on T2-weighted images, were well consistent with histological degeneration. This morphological classification, as shown on T2-weighted images, could also be used in the evaluation of intervertebral disc degeneration. (N.K.)

  9. Magnetic resonance imaging of intervertebral disc degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Hiroshi; Noguchi, Masao (Kitakyushu City Yahata Hospital, Fukuoka (Japan)); Kira, Hideaki; Fujiki, Hiroshi; Shimokawa, Isao; Hinoue, Kaichi

    1993-02-01

    The aim of this study was to correlate the degree of lumbar intervertebral disc degeneration with findings of magnetic resonance imaging (MRI). Seventeen autopsied (from 7 patients) and 21 surgical (from 20 patients) intervertebral discs were used as specimens for histopathological examination. In addition, 21 intervertebral discs were examined on T2-weighted images. Histopathological findings from both autopsied and surgical specimens were well correlated with MRI findings. In particular, T2-weighted images reflected increased collagen fibers and rupture within the fibrous ring accurately. However, when severely degenerated intervertebral discs and hernia protruding the posterior longitudinal ligament existed, histological findings were not concordant well with T2-weighted images. Morphological appearances of autopsy specimens, divided into four on T2-weighted images, were well consistent with histological degeneration. This morphological classification, as shown on T2-weighted images, could also be used in the evaluation of intervertebral disc degeneration. (N.K.).

  10. The formation of planets by disc fragmentation

    Directory of Open Access Journals (Sweden)

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  11. [Physiotherapy in lumbar disc herniation ].

    Science.gov (United States)

    Stoll, T; Germann, D; Hagmann, H

    2001-08-01

    Physiotherapy is the treatment of choice in patients with symptoms caused by a lumbar disc herniation. In clinical practice a broad range of physiotherapeutic modalities has been revealed to be helpful. During the acute stage the efficacy of the McKenzie-concept, mobilisation therapies and traction has been demonstrated in randomized controlled trials with a blind assessor. In addition, pain reducing physical therapies such as cold or electrotherapy and non-steroidal anti-inflammatory drugs, analgesics and/or muscle relaxants are sensible initial accompanying treatments. The effectiveness of active physiotherapies such as training of local strength endurance of back and abdominal muscles has been proven in patients during the chronic stage. The indications for a in-patient rehabilitation programme, for surgery and the danger of developing chronic low back pain are discussed.

  12. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level.

    Science.gov (United States)

    Hakan, Tayfun; Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome.

  13. Lumbar herniated disc: spontaneous regression.

    Science.gov (United States)

    Altun, Idiris; Yüksel, Kasım Zafer

    2017-01-01

    Low back pain is a frequent condition that results in substantial disability and causes admission of patients to neurosurgery clinics. To evaluate and present the therapeutic outcomes in lumbar disc hernia (LDH) patients treated by means of a conservative approach, consisting of bed rest and medical therapy. This retrospective cohort was carried out in the neurosurgery departments of hospitals in Kahramanmaraş city and 23 patients diagnosed with LDH at the levels of L3-L4, L4-L5 or L5-S1 were enrolled. The average age was 38.4 ± 8.0 and the chief complaint was low back pain and sciatica radiating to one or both lower extremities. Conservative treatment was administered. Neurological examination findings, durations of treatment and intervals until symptomatic recovery were recorded. Laségue tests and neurosensory examination revealed that mild neurological deficits existed in 16 of our patients. Previously, 5 patients had received physiotherapy and 7 patients had been on medical treatment. The number of patients with LDH at the level of L3-L4, L4-L5, and L5-S1 were 1, 13, and 9, respectively. All patients reported that they had benefit from medical treatment and bed rest, and radiologic improvement was observed simultaneously on MRI scans. The average duration until symptomatic recovery and/or regression of LDH symptoms was 13.6 ± 5.4 months (range: 5-22). It should be kept in mind that lumbar disc hernias could regress with medical treatment and rest without surgery, and there should be an awareness that these patients could recover radiologically. This condition must be taken into account during decision making for surgical intervention in LDH patients devoid of indications for emergent surgery.

  14. Minimizing cryopreservation-induced loss of disc cell activity for storage of whole intervertebral discs

    Directory of Open Access Journals (Sweden)

    SCW Chan

    2010-06-01

    Full Text Available Severe intervertebral disc (IVD degeneration often requires disc excision and spinal fusion, which leads to loss of spinal segment mobility. Implantation of an allograft disc or tissue engineered disc construct emerges as an alternative to artificial disc replacement for preserving the motion of the degenerated level. Establishment of a bank of cadaveric or engineered cryopreserved discs enables size matching, and facilitates clinical management. However, there is a lack of understanding of the behaviour of disc cells during cryopreservation, as well as how to maximize their survival, such that disc graft properties can be preserved. Here, we report on the effect of alterations in cooling rates, cryoprotective agents (CPAs, and duration of pre-cryopreservation incubation in CPA on cellular activity in whole porcine lumbar discs. Our results indicated that cooling rates of -0.3°C/min and -0.5°C /min resulted in the least loss of metabolic activity in nucleus pulposus (NP and annulus fibrosus (AF respectively, while metabolic activity is best maintained by using a combination of 10% dimethylsulphoxide (DMSO and 10% propylene-glycol (PG as CPA. By the use of such parameters, metabolic activity of the NP and the AF cells could be maintained at 70% and 45%, respectively, of that of the fresh tissue. Mechanical testing and histological evaluation showed no significant differences in mechanical properties or alterations in disc structure compared to fresh discs. Despite the limitations of the animal model, our findings provide a framework for establishing an applicable cryopreservation protocol for human disc allografts or tissue-engineered disc constructs.

  15. Intervertebral Disc Characteristic on Progressive Neurological Deficit

    Directory of Open Access Journals (Sweden)

    Farid Yudoyono

    2017-09-01

    Full Text Available Objective: To examine the intervertebral disc characteristic on magnetic resonance imaging (MRI in lumbar herniated disc (LHD patients with progressive neurological deficit. Methods: Patients were collected retrospectively from Dr. Hasan Sadikin General Hospital Database from 2011–2013 with LHD, had neurological deficit such as radiculopathy and cauda equine syndrome for less than four weeks with a positive sign confirmed by neurological examination and confirmatory with MRI examination. Results: A total of 14 patients with lumbar herniated disc disease (10 males, 4 females suffered from progressive neurological deficit with an average age of (52.07±10.9 years old. Early disc height was 9.38±0.5 mm and progressive neurological deficit state disc height was 4.03±0.53 mm, which were significantly different statisticaly (p<0.01. Symptoms of radiculopathy were seen in 11 patients and cauda equine syndrome in three patients. Modic changes grade 1 was found in five patients, grade 2 in eight patients,grade 3 in one patient, Pfirmman grade 2 in eleven patients and grade 3 in three patients. Thecal sac compression 1/3 compression was seen in four patients and 2/3 compression in ten patients. Conclusions: Neurosurgeon should raise concerns on the characteristic changes of intervertebral disc in magnetic resonance imaging examination to avoid further neural injury in lumbar herniated disc patients.

  16. The slaved disc model for SS 433

    International Nuclear Information System (INIS)

    Whitmire, D.P.; Matese, J.J.

    1980-01-01

    A slaved disc model for SS 433 is investigated in which the beams originate normal to the surface of an accretion disc around a compact object in a binary system. The 13-day period in the 'stationary' system of lines is assumed to be associated with binary orbital motion and the 164-day periodicity in the moving line system is identified with disc precession. As in the slaved disc model for Her X-1, it is assumed that material is processed through the disc rapidly (relative to 164 days) so that the disc precesses at the same rate as the spin axis of the secondary which is driven by the gravitational torque applied by the compact object. If the secondary star does not underfill its critical lobe then the apparent absence of X-ray or optical eclipsing and beam interruption by the secondary places severe constraints on the model. It is shown that the viability of the basic model requires that the mass of the compact object be approximately > 10 times the mass of the secondary. Thus if the slaved disc model is applicable to SS 433 and if the mass of the secondary is approximately > 1 solar mass it follows that the compact object is a massive black hole. (author)

  17. The luminosity of particle beams from thick accretion discs

    International Nuclear Information System (INIS)

    Narayan, R.; Nityananda, R.; Wiita, P.J.

    1983-01-01

    The interaction of the radiation produced in the funnels of thick, highly luminous accretion discs with the walls of these funnels is investigated. Some processes not considered in an earlier discussion have been included. The turbulent mixing of the surface layer with deeper regions acts to reduce the luminosity associated with outflowing matter. The modification of the radiation field by the moving walls is also important. It is found, for the specific funnel geometry studied, corresponding to a radiation luminosity of 8.5 times the Eddington limit Lsub(E), that up to 1.5 Lsub(E) can be carried away as a particle beam, even for an optically thin funnel. This particle luminosity is sensitive to the sound velocity and the mixing efficiency in the walls. (author)

  18. Supernovae and their host galaxies - V. The vertical distribution of supernovae in disc galaxies

    Science.gov (United States)

    Hakobyan, A. A.; Barkhudaryan, L. V.; Karapetyan, A. G.; Mamon, G. A.; Kunth, D.; Adibekyan, V.; Aramyan, L. S.; Petrosian, A. R.; Turatto, M.

    2017-10-01

    We present an analysis of the height distributions of the different types of supernovae (SNe) from the plane of their host galaxies. We use a well-defined sample of 102 nearby SNe appearing inside high-inclined (I ≥ 85°), morphologically non-disturbed S0-Sd host galaxies from the Sloan Digital Sky Survey. For the first time, we show that in all the subsamples of spirals, the vertical distribution of core-collapse (CC) SNe is about twice closer to the plane of the host disc than the distribution of SNe Ia. In Sb-Sc hosts, the exponential scale height of CC SNe is consistent with those of the younger stellar population in the Milky Way (MW) thin disc, while the scale height of SNe Ia is consistent with those of the old population in the MW thick disc. We show that the ratio of scale lengths to scale heights of the distribution of CC SNe is consistent with those of the resolved young stars with ages from ˜10 up to ˜100 Myr in nearby edge-on galaxies and the unresolved stellar population of extragalactic thin discs. The corresponding ratio for SNe Ia is consistent with the same ratios of the two populations of resolved stars with ages from a few 100 Myr up to a few Gyr and from a few Gyr up to ˜10 Gyr, as well as with the unresolved population of the thick disc. These results can be explained considering the age-scale height relation of the distribution of stellar population and the mean age difference between Type Ia and CC SNe progenitors.

  19. Thin Places

    OpenAIRE

    Lockwood, Sandra Elizabeth

    2013-01-01

    This inquiry into the three great quests of the twentieth century–the South Pole, Mount Everest, and the Moon–examines our motivations to venture into these sublime, yet life-taking places. The Thin Place was once the destination of the religious pilgrim seeking transcendence in an extreme environment. In our age, the Thin Place quest has morphed into a challenge to evolve beyond the confines of our own physiology; through human ingenuity and invention, we reach places not meant to accommod...

  20. Intradural disc herniation: how I do it.

    Science.gov (United States)

    Rodrigo, Víctor; Claramonte, Marta; Martín, Mónica; Calatayud, Juan B

    2018-03-12

    Intradural disc herniation is a rare phenomenon in spine surgery. Diagnosis is difficult despite current neuroradiologic imaging techniques. We present a case of a 59-year-old man with lumbar and radicular pain and a recurrent lumbar herniation. A laminectomy was performed after no clear disc herniation in the epidural space was found and an intradural mass was palpable. A durotomy showed an intradural disc fragment that was removed, followed by an arthrodesis. Only intraoperative findings lead to a definitive diagnosis for intradural herniation. A durotomy needs to be performed. In this case, an arthrodesis was necessary to avoid complications of segmental instability.

  1. Spectroscopic Parameters of Lumbar Intervertebral Disc Material

    Science.gov (United States)

    Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

    2009-06-01

    There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

  2. Effect of initial fluid-system pressures on the behavior of a rupture-disc pressure-relief device

    International Nuclear Information System (INIS)

    Hsieh, B.J.; Shin, Y.W.; Kot, C.A.

    1983-01-01

    Rupture disc assemblies are used in piping network systems as a pressure-relief device to protect the system from being exposed to excess pressures. Among the various disc assemblies, the reverse-buckling type is chosen for application in the Clinch River Breeder Reactor. This rupture-disc assembly consists of a portion of a thin spherical shell with its convex side subjected to the fluid system. The reverse-buckling type rupture disc assemblies have been used successfully in environments where the fluid is gas, i.e. highly compressible, and their performances have been judged as adequate in the liquid environment. To analyze the piping system, an analysis method is needed taking into consideration of the fluid/disc interaction, the nonlinear dynamic buckling phenomenon of the disc, and the possible cavitation of the fluid. A computer code SWAAM-I had been written at the Components Technology Division, Argonne National Laboratory. Among its many functions, one is to compute the response of 1-dimensional pressure pulse propagation including the effects of many different types of boundary conditions and possible pipe plasticity

  3. Locally prepared antibiotic sensitivity discs: a substitute for imported ...

    African Journals Online (AJOL)

    Zones of inhibition were compared with those obtained from commercial antibiotic discs. Results obtained showed that discs prepared locally from antibiotic tablets, performed comparably with commercially obtained discs. There was no significant statistical difference between the two tested discs. We therefore recommend ...

  4. Inclination evolution of protoplanetary discs around eccentric binaries

    Science.gov (United States)

    Zanazzi, J. J.; Lai, Dong

    2018-01-01

    It is usually thought that viscous torque works to align a circumbinary disc with the binary's orbital plane. However, recent numerical simulations suggest that the disc may evolve to a configuration perpendicular to the binary orbit ('polar alignment) if the binary is eccentric and the initial disc-binary inclination is sufficiently large. We carry out a theoretical study on the long-term evolution of inclined discs around eccentric binaries, calculating the disc warp profile and dissipative torque acting on the disc. For discs with aspect ratio H/r larger than the viscosity parameter α, bending wave propagation effectively makes the disc precess as a quasi-rigid body, while viscosity acts on the disc warp and twist to drive secular evolution of the disc-binary inclination. We derive a simple analytic criterion (in terms of the binary eccentricity and initial disc orientation) for the disc to evolve towards polar alignment with the eccentric binary. When the disc has a non-negligible angular momentum compared to the binary, the final 'polar alignment' inclination angle is reduced from 90°. For typical protoplanetary disc parameters, the time-scale of the inclination evolution is shorter than the disc lifetime, suggesting that highly inclined discs and planets may exist orbiting eccentric binaries.

  5. Squeeze Film Behaviour in Rotating Porous Annular Discs ...

    African Journals Online (AJOL)

    The squeeze film behaviour between rotating annular discs, when the upper disc with a porous facing approached the parallel lower disc, was theoretically analysed. The lubricant was a magnetic fluid and the external magnetic field was oblique to the lower disc. Expressions were obtained for pressure, load capacity and ...

  6. Investigation of the coatings applied onto brake discs on disc-brake pad pair

    Directory of Open Access Journals (Sweden)

    I. Kiliçaslan

    2009-07-01

    Full Text Available While braking, according to the severity of it, thermal, metallurgical, constructive and tribological occurrences emerge on the brake disc-pad interface. In this study, NiCr was sprayed as bonding layer onto the discs, one ofwhich was coated with Al2O3-TiO2 by plasma spray and the other was coated with NiCr-Cr3C2 by High Velocity Oxygen Fuel (HVOF. In addition, the discs were tested with inertia dynamometer according to SAE’s J2522 testing procedure. The measurements showed that although the pads of the coated discs were exposed to higher braking temperatures, friction coefficient of the disc coated with NiCr- Cr3C2 was obtained 6 % higher compared to the original disc.

  7. Is that lumbar disc symptomatic? Herniated lumbar disc associated with contralateral radiculopathy.

    Science.gov (United States)

    Abdul Jalil, Muhammad Fahmi; Lam, Miu Fei; Wang, Yi Yuen

    2014-05-07

    Herniated lumbar disc may be asymptomatic or associated with lower limb radiculopathy. Most spinal surgeons would offer surgery following a period of conservative measures if the radiological and clinical findings correlate. However, the existing dictum that lumbar radiculopathy should correlate with ipsilateral lumbar disc herniation may not be accurate as it can rarely present with contralateral sciatica. Literature regarding this phenomenon is scarce. Therefore, we report a patient with herniated lumbar disc presenting with predominantly contralateral motor weakness radiculopathy, which resolved after discectomy.

  8. Thin book

    DEFF Research Database (Denmark)

    En lille bog om teater og organisationer, med bidrag fra 19 teoretikere og praktikere, der deltog i en "Thin Book Summit" i Danmark i 2005. Bogen bidrager med en state-of-the-art antologi om forskellige former for samarbejde imellem teater og organisationer. Bogen fokuserer både på muligheder og...

  9. Thin Film

    African Journals Online (AJOL)

    a

    organic substances. KEY WORDS: Photoelectrocatalysis, Titanium dioxide, Cuprous oxide, Composite thin film, Photo electrode. INTRODUCTION ... reddish p-type semiconductor with a direct band gap of 2.0-2.2 eV [18, 19]. ... Photoelectrocatalytic removal of color from water using TiO2 and TiO2/Cu2O electrodes. Bull.

  10. Protoplanetary disc `isochrones' and the evolution of discs in the M˙-Md plane

    Science.gov (United States)

    Lodato, Giuseppe; Scardoni, Chiara E.; Manara, Carlo F.; Testi, Leonardo

    2017-12-01

    In this paper, we compare simple viscous diffusion models for the disc evolution with the results of recent surveys of the properties of young protoplanetary discs. We introduce the useful concept of 'disc isochrones' in the accretion rate-disc mass plane and explore a set of Monte Carlo realization of disc initial conditions. We find that such simple viscous models can provide a remarkable agreement with the available data in the Lupus star forming region, with the key requirement that the average viscous evolutionary time-scale of the discs is comparable to the cluster age. Our models produce naturally a correlation between mass accretion rate and disc mass that is shallower than linear, contrary to previous results and in agreement with observations. We also predict that a linear correlation, with a tighter scatter, should be found for more evolved disc populations. Finally, we find that such viscous models can reproduce the observations in the Lupus region only in the assumption that the efficiency of angular momentum transport is a growing function of radius, thus putting interesting constraints on the nature of the microscopic processes that lead to disc accretion.

  11. Transradicular lumbar disc herniation: An extreme variant of intraradicular disc herniation.

    Science.gov (United States)

    Kasliwal, Manish K; Shimer, Adam L

    2015-01-01

    Intradural or intraradicular lumbar disc herniation (IDH) is a relatively rare condition often diagnosed intraoperatively. We encountered an extreme variant of IDH - a transradicular herniation as the disc material extruded through the lumbar nerve root through a split essentially transecting the nerve root. While failure to recognize intradural and intraradicular disc herniation can lead to failed back surgery, the variant described in the present case could lead to iatrogenic injury and complication if not recognized. A unique case of transradicular lumbar disc herniation in a 25-year-old patient is presented with the depiction of intraoperative images supplementing the text.

  12. Treatment of lumbar disc herniation by percutaneous laser disc decompression (PLDD) and modified PLDD

    Science.gov (United States)

    Chi, Xiao fei; Li, Hong zhi; Wu, Ru zhou; Sui, Yun xian

    2005-07-01

    Objective: To study the micro-invasive operative method and to compare the effect of treatment of PLDD and modified PLDD for Lumbar Disc Herniation. Method: Vaporized part of the nucleus pulposus in single or multiple point after acupuncture into lumbar disc, to reach the purpose of the decompression of the lumbar disc. Result: Among the 19 cases of the regular PLDD group, the excellent and good rate was 63.2%, and among the 40 cases of the modified PLDD group, the excellent and good rate was 82.5%. Conclusion: The modified PLDD has good effect on the treatment for lumbar disc herniation.

  13. Transradicular lumbar disc herniation: An extreme variant of intraradicular disc herniation

    Directory of Open Access Journals (Sweden)

    Manish K Kasliwal

    2015-01-01

    Full Text Available Intradural or intraradicular lumbar disc herniation (IDH is a relatively rare condition often diagnosed intraoperatively. We encountered an extreme variant of IDH - a transradicular herniation as the disc material extruded through the lumbar nerve root through a split essentially transecting the nerve root. While failure to recognize intradural and intraradicular disc herniation can lead to failed back surgery, the variant described in the present case could lead to iatrogenic injury and complication if not recognized. A unique case of transradicular lumbar disc herniation in a 25-year-old patient is presented with the depiction of intraoperative images supplementing the text.

  14. Axial T2* mapping in intervertebral discs: a new technique for assessment of intervertebral disc degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Hoppe, Sven; Quirbach, Sebastian; Krause, Fabian G.; Benneker, Lorin M. [Inselspital, Berne University Hospital, Department of Orthopaedic Surgery, Berne (Switzerland); Mamisch, Tallal C. [Inselspital, Berne University Hospital, Department of Radiology, Berne (Switzerland); Werlen, Stefan [Clinic Sonnenhof, Department of Radiology, Berne (Switzerland)

    2012-09-15

    To demonstrate the potential benefits of biochemical axial T2* mapping of intervertebral discs (IVDs) regarding the detection and grading of early stages of degenerative disc disease using 1.5-Tesla magnetic resonance imaging (MRI) in a clinical setting. Ninety-three patients suffering from lumbar spine problems were examined using standard MRI protocols including an axial T2* mapping protocol. All discs were classified morphologically and grouped as ''healthy'' or ''abnormal''. Differences between groups were analysed regarding to the specific T2* pattern at different regions of interest (ROIs). Healthy intervertebral discs revealed a distinct cross-sectional T2* value profile: T2* values were significantly lower in the annulus fibrosus compared with the nucleus pulposus (P = 0.01). In abnormal IVDs, T2* values were significantly lower, especially towards the centre of the disc representing the expected decreased water content of the nucleus (P = 0.01). In herniated discs, ROIs within the nucleus pulposus and ROIs covering the annulus fibrosus showed decreased T2* values. Axial T2* mapping is effective to detect early stages of degenerative disc disease. There is a potential benefit of axial T2* mapping as a diagnostic tool, allowing the quantitative assessment of intervertebral disc degeneration. circle Axial T2* mapping effective in detecting early degenerative disc disease. (orig.)

  15. Thermal analysis on motorcycle disc brake geometry

    Science.gov (United States)

    W. M. Zurin W., S.; Talib, R. J.; Ismail, N. I.

    2017-08-01

    Braking is a phase of slowing and stop the movement of motorcycle. During braking, the frictional heat was generated and the energy was ideally should be faster dissipated to surrounding to prevent the built up of the excessive temperature which may lead to brake fluid vaporization, thermoelastic deformation at the contact surface, material degradation and failure. In this paper, solid and ventilated type of motorcycle disc brake are being analyse using Computational Fluid Dynamic (CFD) software. The main focus of the analysis is the thermal behaviour during braking for solid and ventilated disc brake. A comparison between both geometries is being discussed to determine the better braking performance in term of temperature distribution. It is found that ventilated disc brake is having better braking performance in terms of heat transfer compare to solid disc.

  16. Low back pain and degenerative disc disease

    OpenAIRE

    Jandrić Slavica; Antić Branislav

    2006-01-01

    Introduction. Various clinical conditions can cause low back pain, and in most cases it is of a degenerative origin. Degenerative disc disease is a common condition which affects young to middle-aged men and women equally. Changes in the mechanical properties of the disc lead to degenerative arthritis in the intervertebral joints, osteophytes, and narrowing the intervertebral foramen or the spinal canal. Pathophysiology. Degenerative cascade, described by Kirkaldy-Willis, is the widely accept...

  17. Myxomatous degeneration of the lumbar intervertebral disc.

    Science.gov (United States)

    Beatty, R A

    1985-08-01

    Sixteen patients were operated on for lumbar pain and pain radiating into the sciatic nerve distribution. In all 16, when the anulus fibrosus was incised, soft, gray disc material extruded under pressure like toothpaste being squeezed from a tube. This syndrome of myxomatous degeneration is a distinct entity, different from classical fibrotic disc degeneration or herniated nucleus pulposus. Surgical removal associated with partial facetectomy produced excellent results. The concept of incompetence of the anulus fibrosis is discussed.

  18. The lowest surface brightness disc galaxy known

    International Nuclear Information System (INIS)

    Davies, J.I.; Phillipps, S.; Disney, M.J.

    1988-01-01

    The discovery of a galaxy with a prominent bulge and a dominant extremely low surface brightness disc component is reported. The profile of this galaxy is very similar to the recently discovered giant low surface brightness galaxy Malin 1. The disc central surface brightness is found to be ∼ 26.4 Rμ, some 1.5 mag fainter than Malin 1 and thus by far the lowest yet observed. (author)

  19. Hygroviscoelasticity of the Human Intervertebral Disc.

    Science.gov (United States)

    1980-07-01

    occurs most frequently in the posterior portion of the disc and results often in pain - ful pressure on the spinal nerves. When high mechanical loads...nodes. This type of damage does not generally, per se, lead to pain symptoms, but because the phenomenon can change the overall stiffness of the disc...are fused with each other to form two bones, the sacrum and the coccyx . Figure 1 shows a lateral view of the vertebral column in the erect position

  20. The Gaia-ESO Survey: New constraints on the Galactic disc velocity dispersion and its chemical dependencies

    Science.gov (United States)

    Guiglion, G.; Recio-Blanco, A.; de Laverny, P.; Kordopatis, G.; Hill, V.; Mikolaitis, Š.; Minchev, I.; Chiappini, C.; Wyse, R. F. G.; Gilmore, G.; Randich, S.; Feltzing, S.; Bensby, T.; Flaccomio, E.; Koposov, S. E.; Pancino, E.; Bayo, A.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Lind, K.; Magrini, L.; Morbidelli, L.; Sacco, G. G.; Ruchti, G.; Worley, C. C.; Zaggia, S.

    2015-11-01

    Context. Understanding the history and the evolution of the Milky Way is one of the main goals of modern astrophysics. In particular, the formation of the Galactic disc is a key problem of Galactic archaeology. Aims: We study the velocity dispersion behaviour of Galactic disc stars as a function of the [Mg/Fe] ratio, which for small metallicity bins can be used as a proxy of relative age. This key relation is essential to constrain the formation mechanisms of the disc stellar populations as well as the cooling and settling processes. Methods: We used the recommended parameters and chemical abundances of 7800 FGK Milky Way field stars from the second internal data release of the Gaia-ESO spectroscopic Survey. These stars were observed with the GIRAFFE spectrograph (HR10 and HR21 setups), and cover a large spatial volume in the intervals 6 +0.20 dex for the radial component. First, the velocity dispersion increases with [Mg/Fe] at all [Fe/H] ratios for the thin-disc stars, and then it decreases for the thick-disc population at the highest [Mg/Fe] abundances. Similar trends are observed for several bins of [Mg/Fe] within the errors for the azimuthal velocity dispersion, while a continuous increase with [Mg/Fe] is observed for the vertical velocity dispersion. The velocity dispersion decrease agrees with previous measurements of the RAVE survey, although it is observed here for a greater metallicity interval and a larger spatial volume. Conclusions: Thanks to the Gaia-ESO Survey data, we confirm the existence of [Mg/Fe]-rich thick-disc stars with cool kinematics in the generally turbulent context of the primitive Galactic disc. This is discussed in the framework of the different disc formation and evolution scenarios. Based on observations collected with the FLAMES spectrograph at the VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia-ESO Large Public Survey, programme 188.B-3002

  1. The extremely truncated circumstellar disc of V410 X-ray 1: a precursor to TRAPPIST-1?

    Science.gov (United States)

    Boneberg, D. M.; Facchini, S.; Clarke, C. J.; Ilee, J. D.; Booth, R. A.; Bruderer, S.

    2018-02-01

    Protoplanetary discs around brown dwarfs and very low mass stars offer some of the best prospects for forming Earth-sized planets in their habitable zones. To this end, we study the nature of the disc around the very low mass star V410 X-ray 1, whose SED is indicative of an optically thick and very truncated dust disc, with our modelling suggesting an outer radius of only 0.6 au. We investigate two scenarios that could lead to such a truncation, and find that the observed SED is compatible with both. The first scenario involves the truncation of both the dust and gas in the disc, perhaps due to a previous dynamical interaction or the presence of an undetected companion. The second scenario involves the fact that a radial location of 0.6 au is close to the expected location of the H2O snowline in the disc. As such, a combination of efficient dust growth, radial migration, and subsequent fragmentation within the snowline leads to an optically thick inner dust disc and larger, optically thin outer dust disc. We find that a firm measurement of the CO J = 2-1 line flux would enable us to distinguish between these two scenarios, by enabling a measurement of the radial extent of gas in the disc. Many models we consider contain at least several Earth-masses of dust interior to 0.6 au, suggesting that V410 X-ray 1 could be a precursor to a system with tightly-packed inner planets, such as TRAPPIST-1.

  2. CT findings of calcified herniated lumbar disc

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyo Kun; Lee, Jun Hyung [Chang Dong Armed Forces Evacuation Hospital, Seoul (Korea, Republic of)

    1987-12-15

    Computed tomography (CT) of 10 calcified herniated lumber discs among 46 operated cases were analysed at the aspects of incidence, location, shape, etc. The results are as follows: 1. The incidence of calcification is 22% (10/46). 2. Among 10 cases, 3 cases are at the level of L4-5 disc space and 7 cases are at the level of L5-S1 disc space. 3. Central herniation (8 cases) are more common than posterolateral herniation (2 cases). 4. Linear or band-like calcifications in the periphery of herniated disc (annulus fibrosus type) are 6 cases and dense patchy calcification in the central portion of herniated disc (nucleus pulposus type) are 4 cases. 5. Two cases (50%) of 4 cases with nucleus pulposus type calcification were found to be ruptured at operation, but none of 6 annulus fibrous calcification types showed rupture. 6. Because more wide operation field and invasive exploration were required in calcified cases than non-calcified cases, it is suggested to evaluate the presence, location, and type of calcification in herniated disc in detail.

  3. A Photocatalytic Rotating Disc Reactor with TiO₂ Nanowire Arrays Deposited for Industrial Wastewater Treatment.

    Science.gov (United States)

    Li, Fang; Szeto, Wai; Huang, Haibao; Li, Jiantao; Leung, Dennis Y C

    2017-02-22

    A photocatalytic rotating disc reactor (PRD-reactor) with TiO₂ nanowire arrays deposited on a thin Ti plate is fabricated and tested for industrial wastewater treatment. Results indicate that the PRD-reactor shows excellent decolorization capability when tested with methyl orange (>97.5%). Advanced oxidation processes (AOP), including photocatalytic oxidation and photolytic reaction, occurred during the processing. Efficiency of the AOP increases with reduction in light absorption pathlength, which enhanced the photocatalytic reaction, as well as by increasing oxygen exposure of the wastewater thin film due to the rotating disc design. It is found that, with a small dosage of hydrogen peroxide, the mineralization efficiency of industrial biodegraded wastewater can be enhanced, with a superior mineralization of >75% total organic carbon (TOC) removal. This is due to the fact that the TiO₂ photocatalysis and hydrogen peroxide processes generate powerful oxidants (hydroxyl radicals) that can strongly improve photocatalytic oxidation efficiency. Application of this industrial wastewater treatment system is benefited from the TiO₂ nanowire arrays, which can be fabricated by a mild solvothermal method at 80 °C and under atmospheric pressure. Similar morphologies and microstructures are found for the TiO₂ nanowire arrays deposited on a large metal Ti disc, which makes the wastewater treatment process more practical and economical.

  4. Modelling the Galactic disc: perturbed distribution functions in the presence of spiral arms

    Science.gov (United States)

    Monari, Giacomo; Famaey, Benoit; Siebert, Arnaud

    2016-04-01

    Starting from an axisymmetric equilibrium distribution function (DF) in action space, representing a Milky Way thin disc stellar population, we use the linearized Boltzmann equation to explicitly compute the response to a three-dimensional spiral potential in terms of the perturbed DF. This DF, valid away from the main resonances, allows us to investigate a snapshot of the velocity distribution at any given point in three-dimensional configuration space. Moreover, the first-order moments of the DF give rise to non-zero radial and vertical bulk flows - namely breathing modes - qualitatively similar to those recently observed in the extended solar neighbourhood. We show that these analytically predicted mean stellar motions are in agreement with the outcome of test-particle simulations. Moreover, we estimate for the first time the reduction factor for the vertical bulk motions of a stellar population compared to the case of a cold fluid. Such an explicit expression for the full perturbed DF of a thin disc stellar population in the presence of spiral arms will be helpful in order to dynamically interpret the detailed information on the Milky Way disc stellar kinematics that will be provided by upcoming large astrometric and spectroscopic surveys of the Galaxy.

  5. Thin melanoma.

    Science.gov (United States)

    Elder, David E

    2011-03-01

    The incidence of malignant melanoma is increasing and a preponderance of the melanomas diagnosed today are "thin in terms of Breslow criteria. Although thin melanomas, as a group, are associated with a very good prognosis, a subset of these tumors may metastasize and cause death. These cases can be identified by using prognostic models, including the "standard" American Joint Committee on Cancer criteria, and other attributes identified in follow-up studies. To review the history of concepts of prognostic modeling in melanoma, focusing on thin melanomas. Selected literature. About 40 years ago, it was realized that malignant melanoma, once almost uniformly fatal, could be divided into categories with better or worse prognosis through the use of prognostic models. The first simple models, Clark levels of invasion and Breslow thickness, are still in use. Thickness remains the single most useful variable. Breslow recognized that melanomas less than 0.76 mm in thickness were associated with a very good prognosis, with no metastases in his limited initial study. The American Joint Committee on Cancer selected a cutoff of 1.0 mm, which achieves a similar result, with stage modifiers, although some metastases and deaths do occur with stage I lesions. Clark demonstrated an almost equally good prognosis for his level II invasive melanomas and recognized that most of these lesions, although invasive, lacked the ability to form tumors or to undergo mitosis in the dermis and were therefore "nontumorigenic" and "nonmitogenic" and lacked competence for metastasis. Studies of these low-risk melanomas have led to the development of criteria for earlier diagnosis and a steady, but still inadequate, improvement in prognosis for melanoma overall. Multivariable models currently can identify groups of patients within the "thin melanoma" category whose prognosis varies, from a disease-free survival of close to 100% to about 70%. Prognosis declines more or less linearly with increasing

  6. thin films

    Indian Academy of Sciences (India)

    The anionic precursor was 1% H2O2 solution. Both the cationic and anionic precursors were kept at room temperature (∼300 K). One SILAR cycle consists of two steps: (i) adsorption of Sn4+ ions on the substrate surface for 20 s and (ii) reaction with H2O2 solution for 40 s to form stable SnO2:H2O thin film on the substrate.

  7. Star-disc interaction in galactic nuclei: formation of a central stellar disc

    Science.gov (United States)

    Panamarev, Taras; Shukirgaliyev, Bekdaulet; Meiron, Yohai; Berczik, Peter; Just, Andreas; Spurzem, Rainer; Omarov, Chingis; Vilkoviskij, Emmanuil

    2018-02-01

    We perform high resolution direct N-body simulations to study the effect of an accretion disc on stellar dynamics in an active galactic nucleus (AGN). We show that the interaction of the nuclear stellar cluster (NSC) with the gaseous disc (AD) leads to formation of a stellar disc in the central part of the NSC. The accretion of stars from the stellar disc onto the super-massive black hole is balanced by the capture of stars from the NSC into the stellar disc, yielding a stationary density profile. We derive the migration time through the AD to be 3% of the half-mass relaxation time of the NSC. The mass and size of the stellar disc are 0.7% of the mass and 5% of the influence radius of the super-massive black hole. An AD lifetime shorter than the migration time would result in a less massive nuclear stellar disc. The detection of such a stellar disc could point to past activity of the hosting galactic nucleus.

  8. Residual herniated disc material following hemilaminectomy in chondrodystrophic dogs with thoracolumbar intervertebral disc disease.

    Science.gov (United States)

    Roach, W J; Thomas, M; Weh, J M; Bleedorn, J; Wells, K

    2012-01-01

    To evaluate the presence of residual disc material within the vertebral canal following hemilaminectomy in chondrodystrophic dogs with thoracolumbar intervertebral disc disease. Forty dogs were treated by hemilaminectomy. Computed tomography was performed preoperatively and immediately postoperatively. The vertebral canal height, width, area, and herniated disc material area were measured. Maximum filling percentage (MFP), residual disc percentage (RDP), maximum residual filling percentage (MRFP), and residual filling percentage (RFP) were calculated. Clinical outcome was determined by telephone interviews. Residual disc material was present in 100% of the dogs. Mean MFP = 55.4% (range 25.9-82.3%; median 56.9%). Mean RDP = 50.3% (range 2.6-155.8%; median 47.9%). Mean MRFP = 30.8% (range 4.9-60%; median 30.1%). Mean RFP = 19.8% (range 4.8-45%; median 19.0%). All dogs were ambulatory with voluntary urination at the long-term follow-up (range: 88-735 days). Residual disc was present in all dogs following hemilaminectomy for intervertebral disc disease. Residual disc was not associated with failure to achieve functional recovery in these cases.

  9. A Simulation Model of Focus and Radial Servos in Compact Disc Players with Disc Surface Defects

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

    2004-01-01

    Compact Disc players have been on the market in more than two decades.As a consequence most of the control servo problems have been solved. A large remaining problem to solve is the handling of Compact Discs with severe surface defects like scratches and fingerprints. This paper introduces a method...

  10. [Imaging study of lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation].

    Science.gov (United States)

    Yu, Qing-yang; Yang, Cun-rui; Yu, Lang-tao

    2009-04-01

    Using regional assignment to forked method to study lumbar intervertebral disc hemiation (bugle, hernia, prolapse) dependablity and reason of lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation. From March 2005 to October 2006, 120 patients of match condition from orthopaedics dept and rehabilitative dept of the Boai hospital of Longyan were studied. All patients were equally divided into two groups according to whether or not accompany with symptom of lumbar intervertebral disc herniation. There was not statistical difference in sex, age, course of disease, segment of intervertebral disc between two groups. Sixty patients of symptomatic lumbar intervertebral disc herniation were equally divided into three groups according to (bugle, hernia, prolapse) image on CT. Sixty patients of asymptomatic lumbar intervertebral disc herniation were equally divided into three groups according to (bugle, hernia, prolapse) image on CT. The age was 20-59 years old with an average of 38.5 years. Using regional assignment to give a mark respectively for every group. The sagittal diameter index (SI), anterior diastema of flaval ligaments, the width of superior outlet of latero-crypt, anteroposterior diameter of dura sac were respectively measured by sliding caliper. CT value and protrusible areas were respectively evaluated by computer tomography. Adopting mean value to measure three times. (1) There were not statistical difference in SI, CT value, hernia areas, anteroposterior diameter of dura sac between two groups (symptomatic lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation). There were statistical difference in the width of superior outlet of latero-crypt, anterior diastema of flaval ligaments between two groups (symptomatic lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation). (2) There were statistical difference in protrusible type,protrusible segment

  11. Cervical disc hernia operations through posterior laminoforaminotomy

    Directory of Open Access Journals (Sweden)

    Coskun Yolas

    2016-01-01

    Full Text Available Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. Results: The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years. Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%. On control examinations, there was no finding of instability or cervical kyphosis. Conclusion: Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis.

  12. Only marginal alignment of disc galaxies

    Science.gov (United States)

    Andrae, René; Jahnke, Knud

    2011-12-01

    Testing theories of angular-momentum acquisition of rotationally supported disc galaxies is the key to understanding the formation of this type of galaxies. The tidal-torque theory aims to explain this acquisition process in a cosmological framework and predicts positive autocorrelations of angular-momentum orientation and spiral-arm handedness, i.e. alignment of disc galaxies, on short distance scales of 1 Mpc h-1. This disc alignment can also cause systematic effects in weak-lensing measurements. Previous observations claimed discovering these correlations but are overly optimistic in the reported level of statistical significance of the detections. Errors in redshift, ellipticity and morphological classifications were not taken into account, although they have a significant impact. We explain how to rigorously propagate all the important errors through the estimation process. Analysing disc galaxies in the Sloan Digital Sky Survey (SDSS) data base, we find that positive autocorrelations of spiral-arm handedness and angular-momentum orientations on distance scales of 1 Mpc h-1 are plausible but not statistically significant. Current data appear not good enough to constrain parameters of theory. This result agrees with a simple hypothesis test in the Local Group, where we also find no evidence for disc alignment. Moreover, we demonstrate that ellipticity estimates based on second moments are strongly biased by galactic bulges even for Scd galaxies, thereby corrupting correlation estimates and overestimating the impact of disc alignment on weak-lensing studies. Finally, we discuss the potential of future sky surveys. We argue that photometric redshifts have too large errors, i.e. PanSTARRS and LSST cannot be used. Conversely, the EUCLID project will not cover the relevant redshift regime. We also discuss the potentials and problems of front-edge classifications of galaxy discs in order to improve the autocorrelation estimates of angular-momentum orientation.

  13. Cervical disc hernia operations through posterior laminoforaminotomy.

    Science.gov (United States)

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years). Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%). On control examinations, there was no finding of instability or cervical kyphosis. Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis.

  14. Percutaneous laser disc decompression for lumbar disc hernia: indications based on Lasegue's Sign.

    Science.gov (United States)

    Iwatsuki, Koichi; Yoshimine, Toshiki; Awazu, Kunio

    2007-02-01

    The present study was conducted to establish reasonable indications of patient neurological manifestations for use of percutaneous laser disc decompression (PLDD). PLDD is a less invasive surgical procedure for lumbar disc hernia, whose indications have been described on the basis of radiographical findings. Sixty-five consecutive patients (45 men and 20 women) with lumbar disc hernia were treated with PLDD by applying a diode laser (wavelength 805 nm). A total of 450-1,205 joules (average, 805.5 joules) were delivered per disc. All patients suffered from radicular pain. They were divided based on the presence of Lasegue's sign. The post-procedure results at 1 week and 1 year were compared between the groups. PLDD was effective for patients with Lasegue's sign (80.0%), but ineffective for those without the sign. The present study suggests that Lasegue's sign in patients is an indication of PLDD for lumbar disc hernia.

  15. The Dynamic Similitude Design Method of Thin Walled Structures and Experimental Validation

    Directory of Open Access Journals (Sweden)

    Zhong Luo

    2016-01-01

    Full Text Available For the applicability of dynamic similitude models of thin walled structures, such as engine blades, turbine discs, and cylindrical shells, the dynamic similitude design of typical thin walled structures is investigated. The governing equation of typical thin walled structures is firstly unified, which guides to establishing dynamic scaling laws of typical thin walled structures. Based on the governing equation, geometrically complete scaling law of the typical thin walled structure is derived. In order to determine accurate distorted scaling laws of typical thin walled structures, three principles are proposed and theoretically proved by combining the sensitivity analysis and governing equation. Taking the thin walled annular plate as an example, geometrically complete and distorted scaling laws can be obtained based on the principles of determining dynamic scaling laws. Furthermore, the previous five orders’ accurate distorted scaling laws of thin walled annular plates are presented and numerically validated. Finally, the effectiveness of the similitude design method is validated by experimental annular plates.

  16. DZ Chamaeleontis: a bona fide photoevaporating disc

    Science.gov (United States)

    Canovas, H.; Montesinos, B.; Schreiber, M. R.; Cieza, L. A.; Eiroa, C.; Meeus, G.; de Boer, J.; Ménard, F.; Wahhaj, Z.; Riviere-Marichalar, P.; Olofsson, J.; Garufi, A.; Rebollido, I.; van Holstein, R. G.; Caceres, C.; Hardy, A.; Villaver, E.

    2018-02-01

    Context. DZ Cha is a weak-lined T Tauri star (WTTS) surrounded by a bright protoplanetary disc with evidence of inner disc clearing. Its narrow Hα line and infrared spectral energy distribution suggest that DZ Cha may be a photoevaporating disc. Aims: We aim to analyse the DZ Cha star + disc system to identify the mechanism driving the evolution of this object. Methods: We have analysed three epochs of high resolution optical spectroscopy, photometry from the UV up to the sub-mm regime, infrared spectroscopy, and J-band imaging polarimetry observations of DZ Cha. Results: Combining our analysis with previous studies we find no signatures of accretion in the Hα line profile in nine epochs covering a time baseline of 20 yr. The optical spectra are dominated by chromospheric emission lines, but they also show emission from the forbidden lines [SII] 4068 and [OI] 6300Å that indicate a disc outflow. The polarized images reveal a dust depleted cavity of 7 au in radius and two spiral-like features, and we derive a disc dust mass limit of Mdust 80 MJup) companions are detected down to 0.̋07 ( 8 au, projected). Conclusions: The negligible accretion rate, small cavity, and forbidden line emission strongly suggests that DZ Cha is currently at the initial stages of disc clearing by photoevaporation. At this point the inner disc has drained and the inner wall of the truncated outer disc is directly exposed to the stellar radiation. We argue that other mechanisms like planet formation or binarity cannot explain the observed properties of DZ Cha. The scarcity of objects like this one is in line with the dispersal timescale (≲105 yr) predicted by this theory. DZ Cha is therefore an ideal target to study the initial stages of photoevaporation. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 097.C-0536. Based on data obtained from the ESO Science Archive Facility under request number 250112.

  17. Synthesis of ZnO Hexagonal Micro Discs on Glass Substrates Using the Spray Pyrolysis Technique

    Science.gov (United States)

    Ikhmayies, Shadia J.; Zbib, Mohamad B.

    2017-07-01

    Zinc oxide (ZnO) is an important transparent conducting oxide of potential use in solar cells, electronics, photoelectronics, and sensors. In this work ZnO micro discs were synthesized in thin film form on glass substrates using the low cost spray pyrolysis method. The films were prepared from a precursor solution of ZnCl2 in distilled water at a substrate temperature of 300 ± 5°C. The as-synthesized samples were analyzed with x-ray diffraction, scanning electron microscopy, and x-ray energy dispersive spectroscopy (EDS). The morphology of the films showed randomly distributed micro discs of hexagonal shape. The EDS reports showed that the films contained Cl and Fe. Size analysis was performed using ImageJ software, where the average diameter was found to be 4.8 ± 0.9 μm, and the average thickness was found to be 254 ± 43 nm.

  18. Spiral arms in thermally stratified protoplanetary discs

    Science.gov (United States)

    Juhász, Attila; Rosotti, Giovanni P.

    2018-02-01

    Spiral arms have been observed in nearly a dozen protoplanetary discs in near-infrared scattered light and recently also in the submillimetre continuum. While one of the most compelling explanations is that they are driven by planetary or stellar companions, in all but one cases such companions have not yet been detected and there is even ambiguity on whether the planet should be located inside or outside the spirals. Here, we use 3D hydrodynamic simulations to study the morphology of spiral density waves launched by embedded planets taking into account the vertical temperature gradient, a natural consequence of stellar irradiation. Our simulations show that the pitch angle of the spirals in thermally stratified discs is the lowest in the disc mid-plane and increases towards the disc surface. We combine the hydrodynamic simulations with 3D radiative transfer calculations to predict that the pitch angle of planetary spirals observed in the near-infrared is higher than in the submillimetre. We also find that in both cases the spirals converge towards the planet. This provides a new powerful observational method to determine if the perturbing planet is inside or outside the spirals, as well as map the thermal stratification of the disc.

  19. Active galactic nucleus outflows in galaxy discs

    Science.gov (United States)

    Hartwig, Tilman; Volonteri, Marta; Dashyan, Gohar

    2018-05-01

    Galactic outflows, driven by active galactic nuclei (AGNs), play a crucial role in galaxy formation and in the self-regulated growth of supermassive black holes (BHs). AGN feedback couples to and affects gas, rather than stars, and in many, if not most, gas-rich galaxies cold gas is rotationally supported and settles in a disc. We present a 2D analytical model for AGN-driven outflows in a gaseous disc and demonstrate the main improvements, compared to existing 1D solutions. We find significant differences for the outflow dynamics and wind efficiency. The outflow is energy-driven due to inefficient cooling up to a certain AGN luminosity (˜1043 erg s-1 in our fiducial model), above which the outflow remains momentum-driven in the disc up to galactic scales. We reproduce results of 3D simulations that gas is preferentially ejected perpendicular to the disc and find that the fraction of ejected interstellar medium is lower than in 1D models. The recovery time of gas in the disc, defined as the free-fall time from the radius to which the AGN pushes the ISM at most, is remarkably short, of the order 1 Myr. This indicates that AGN-driven winds cannot suppress BH growth for long. Without the inclusion of supernova feedback, we find a scaling of the BH mass with the halo velocity dispersion of MBH ∝ σ4.8.

  20. Footprint mismatch in lumbar total disc arthroplasty.

    Science.gov (United States)

    Gstoettner, Michaela; Michaela, Gstoettner; Heider, Denise; Denise, Heider; Liebensteiner, Michael; Bach, Christian Michael; Michael, Bach Christian

    2008-11-01

    Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required.

  1. Selection of Tubular and Endoscopic Transforaminal Disc Procedures Based on Disc Size, Location, and Characteristics

    Science.gov (United States)

    Palea, Ovidiu; Granville, Michelle

    2018-01-01

    The clinical effectiveness of percutaneous and transforaminal endoscopic discectomy procedures has been evaluated by the system used or compared to open laminectomy or micro-discectomy but are not evaluated based on the location and characteristics of the abnormal disc. This review proposes that outcomes are primarily related to disc size, biomechanics, location, and associated segmental fibrotic and bone changes as well as the surgeon's skill in using various systems rather than the specific system used. In these cases, the surgeon needs to decide if the goal of the procedure is simply internal decompression of an abnormal but contained herniated disc or release of the entrapped nerve root by a large contained disc, extruded and migrated disc fragment, or coexistent foraminal stenosis. Percutaneous and tubular transforaminal procedures are quite different, technically ranging from simple discectomy aspirating probes to larger endoscopic systems, providing the capability to remove large extruded free disc fragments, with or without foraminotomy. Recently, the ability to perform interbody fusion has been added to the range of procedures able to be performed endoscopically. At the same time, biologic solutions to disc degeneration are rapidly evolving and may have a place in combination with these procedures. This article reviews the interrelationship between clinical signs and symptoms, radiologic findings, and the biochemistry and biomechanics of the affected disc segment. Understanding the role played by all these factors enables the surgeon to evaluate both the disc and surrounding bone structures pre-operatively to determine if the clinical signs and symptoms are related to enlargement and displacement of a contained disc or compression or impingement of the nerve root. Based on this, the surgeon can choose different surgical systems, allowing simple decompression of a contained disc, possibly adding biologics, with a 'small' system, while a large

  2. Determination of residual stresses and natural frequencies of roll-tensioned disc by a dynamic simulation of the rolling process

    Science.gov (United States)

    Skordaris, G.; Bouzakis, K.-D.; Tasoulas, D.

    2017-02-01

    Roll tensioning is a common method for increasing locally the superficial strength of thin circular saws and in this way their dynamic stability. Through roll tensioning, residual stresses are induced into the disc material leading to a significant enhancement of its dynamic stiffness. In this paper, a FEM-methodology is proposed for determining the developed residual stresses in the discs after rolling and for investigating their effects on the circular saw natural frequencies. More specifically, a 3D-FEM model was developed for the dynamic simulation of the rolling process on circular saws, using the LS-DYNA software. This model enables the explicit determination of the developed residual stresses in the roll-tensioned discs. Furthermore, the natural frequencies of the pre-stressed circular saws were calculated by the ANSYS software. In these calculations, the already determined residual stresses were taken into consideration. Different distances of the roll-tensioned zone from the disc centre were taken into account for estimating their effect on the disc’s natural frequencies. By the proposed methodology, optimum roll-tensioning conditions can be predicted for improving the dynamic behaviour of thin circular saws during cutting.

  3. Quasar emission lines as probes of orientation: implications for disc wind geometries and unification

    Science.gov (United States)

    Matthews, J. H.; Knigge, C.; Long, K. S.

    2017-05-01

    The incidence of broad absorption lines (BALs) in quasar samples is often interpreted in the context of a geometric unification model consisting of an accretion disc and an associated outflow. We use the Sloan Digital Sky Survey quasar sample to test this model by examining the equivalent widths (EWs) of C IV 1550 Å, Mg II 2800 Å, [O III] 5007 Å and C III] 1909 Å. We find that the emission line EW distributions in BAL and non-BAL quasars are remarkably similar - a property that is inconsistent with scenarios in which a BAL outflow rises equatorially from a geometrically thin, optically thick accretion disc. We construct simple models to predict the distributions from various geometries; these models confirm the above finding and disfavour equatorial geometries. We show that obscuration, line anisotropy and general relativistic effects on the disc continuum are unlikely to hide an EW inclination dependence. We carefully examine the radio and polarization properties of BAL quasars. Both suggest that they are most likely viewed (on average) from intermediate inclinations, between type 1 and type 2 active galactic nuclei (AGN). We also find that the low-ionization BAL quasars in our sample are not confined to one region of the 'Eigenvector 1' parameter space. Overall, our work leads to one of the following conclusions, or some combination thereof: (I) the continuum does not emit like a geometrically thin, optically thick disc; (II) BAL quasars are viewed from similar angles to non-BAL quasars, that is, low inclinations and (III) geometric unification does not explain the fraction of BALs in quasar samples.

  4. Jamming Transition: Heptagons, Pentagons, and Discs

    Directory of Open Access Journals (Sweden)

    Xu Yuanyuan

    2017-01-01

    Full Text Available The jamming behavior of a system composed of discs has been well documented. However, it remains unclear how a granular system consisting of non-spherical particles transitions between unjammed and jammed states. Here, we present compression experiments to study the jamming transition of 2D granular materials composed of photoelastic heptagonal particles and compare these results to data for discs and pentagons. We determine the critical packing fraction of heptagons and make a comparison to discs and pentagons. In the experiment, we subject 618 heptagonal particles to cyclic compression. We track the motion (inlcuding rotations of the particles, and we measure forces on particles by photoelasticity. We observe a power law relationship between the average contact number (Z and the pressure (P. Furthermore, we classify the type of contacts by the relative orientation of pairs of contacting particles (creating point-to-face and face-to-face contacts, and we explore the evolution of the contacts during jamming.

  5. On the formation of exponential discs

    International Nuclear Information System (INIS)

    Yoshii, Yuzuru; Sommer-Larsen, Jesper

    1989-01-01

    Spiral galaxy discs are characterized by approximately exponential surface luminosity profiles. In this paper the evolutionary equations for a star-forming, viscous disc are solved analytically or semi-analytically. It is shown that approximately exponential stellar surface density profiles result if the viscous time-scale t ν is comparable to the star-formation time scale t * everywhere in the disc. The analytical solutions are used to illuminate further on the issue of why the above mechanism leads to resulting exponential stellar profiles under certain conditions. The sensitivity of the solution to variations of various parameters are investigated and show that the initial gas surface density distribution has to be fairly regular in order that final exponential stellar surface density profiles result. (author)

  6. OPTIC DISC MELANOCYTOMA: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Sahiba Bedi

    2016-08-01

    Full Text Available Melanocytoma of the optic disc is a rare ophthalmic tumour that arises from melanocytes and is a variant of the melanocytic nevus. It occurs on the optic disc and often extends into the peripapillary retina and choroid. It appears as a dark brown or black lesion, typically small and is almost always unilateral. Although traditionally believed to be a relatively stationary lesion, it is now known to exhibit minor enlargement in 10–15% of cases and can cause minor visual loss by a variety of mechanisms. 1-2% cases can transform to malignant melanoma. We present a case report of a 65-year-old female whose dilated fundus examination of the right eye revealed a circular, pigmented and elevated lesion about 1.5 mm in size covering almost whole of the optic nerve head except for the superior rim, suggestive of optic disc melanocytoma.

  7. 'Hard discs' associated with lumbar disc herniation: CT analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Il Kwon; Bang, Dae Hong; Yim, Jung Ik; Lee, Jae Mun; Bahk, Yong Whee [Catholic University Medical College, Seoul (Korea, Republic of)

    1989-02-15

    Thirty cases showing hard discs were collected from 206 consecutive cases of posterior disk herniation during the past one and a half years period. According to the shape of hard disk and the presence of marginal bone defect (MBD) of vertebral end plate, 30 cases could be categorized into 4 distinct groups. They were small hard disc with focal MBD (group 1), large hard disc with broad based MBD (group 2), hard disc separated from vertebral body without MBD (group 3) and hard disc fused with vertebral body without MBD (group 4). There were 14 patients in group 1. In all but one case, the hard disc and MBDs were located at the paramedial aspect of the posterior margin of the end plate. Ten (76.9%) of these had Schmorl's nodes and these were considered to represented an avulsion from the weakened bone margin as the disk herniated acutely. The posterior longitudinal ligament seemed to have prevented detachment of the bony fragment. Group 2 included 2 patients and CT findings as well as plain X-ray features were identical to a limbus vertebra. This was considered to represent passive displacement of bony fragment by the intravertebral herniation of the disk. Nine patients belonged to group 3 and represent dystrophic calcifications of herniated disk. Group 4 included 5 patients and was disclosed as a simple osteophyte. From our study, it was concluded; (1) that the hard disc seen in lumbar CT scan was probably the results of the detachment of a bone fragment from the vertebral end plate which has an underlying weak area due to the herniated disc as well as a calcification or osteophyte formation and (2) specific terms (avulsed fragment, limbus vertebra, calcification or spur formation) is more preferable to use than hard disc which is inaccurate.

  8. Expression of heparanase isoforms in intervertebral discs classified according to Pfirrmann grading system for disc degeneration.

    Science.gov (United States)

    Rodrigues, Luciano Miller Reis; Oliveira, Lilian Zerbinatti de; Pinhal, Maria Aparecida da Silva

    2013-06-01

    This is a quantitative study of heparanase isoforms expression in degenerative and nondegenerative intervertebral discs (IVDs). To quantify the expression of both heparanase isoforms (HPSE1 and HPSE2) in IVD tissues as classified by different degeneration grades using the Pfirrmann grading system, and to correlate the expression with the loss of extracellular matrix molecules observed in patients with the disease. The loss of proteoglycans as observed in IVD degeneration may occur due to the enhanced expression of matrix degrading enzymes, such as heparanase. However, the heparanase function in IVD degeneration remains unclear. This study comprised 53 surgical samples of degenerative discs obtained from patients with lumbar disc degeneration and 12 control samples collected from healthy individuals without any degenerative lumbar disc alterations who had accidental spine fractures.All patients underwent magnetic resonance imaging based on the Pfirrmann grading system for disc degeneration. Only the specimens that were classified according to magnetic resonance imaging evaluations as Pfirrmann grades I, II, III, and IV were analyzed.The tissue sections of the disc samples were subject to immunohistochemical staining with antibodies against the heparanase isoforms and to quantitative real time PCR to amplify heparanase isoforms cDNA. Protein and mRNA expressions were quantified. Analysis of variance and Student t test were used to compare the means of the study populations. The data demonstrated a gradual increase in both the heparanase isoform protein expression and disc degeneration progression. Besides, mRNA expression of both heparanase isoforms were significantly higher in degenerative than nondegenerative IVDs. The overexpression of HPSE1 and HPSE2 in the intervertebral degenerated discs suggests a role for these factors in mediating extracellular matrix remodeling in degenerative discs during disease development.

  9. Natural course of lumber disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Tokioka, Takamitsu; Shimada, Kimio; Tanaka, Yuzo; Oshige, Toshihisa; Miyakoshi, Koichi [Okayama Rosai Hospital (Japan)

    1998-09-01

    Thirty-two cases of lumbar disc herniation were sequentially followed by MR imagings in order to ascertain its natural course. Herniation consisted of protrusion in 6 cases, extrusion in 13 cases, and sequestration in 13 cases. We analysed the durations until the herniation regressed more than 50% of its A-P diameter. The mean duration was 8.2 months for extrusion, and 5.3 months for sequestration. Only 2 cases of protrusion regressed within 12 months. Huge disc herniations with central protrusion in particular showed slight spontaneous regression. (author)

  10. Cells and Biomaterials for Intervertebral Disc Regeneration

    CERN Document Server

    Grad, Sibylle

    2010-01-01

    Disorders related to the intervertebral disc (IVD) are common causes of morbidity and of severe life quality deterioration. IVD degeneration, although in many cases asymptomatic, is often the origin of painful neck and back diseases. In Western societies IVD related pain and disability account for enormous health care costs as a result of work absenteeism and thus lost production, disability benefits, medical and insurance expenses. Although only a small percentage of patients with disc disorders finally will undergo surgery, spinal surgery has been one of the fastest growing disciplines in th

  11. Imaging characteristics of noncontained migrating disc fragment and cyst

    International Nuclear Information System (INIS)

    Eerens, I.; Demaerel, P.; Haven, F.; Wilms, G.; Loon, J. van; Calenbergh, F. van

    2001-01-01

    The purpose of this article is to review less common presentations of degenerative disc disease on MR imaging. The images of eight patients were retrospectively analyzed. Six of them had transligamentous (or noncontained) disc herniations, the fragments of which were located in the posterior epidural space in three of them. One patient had a transdural disc fragment and one patient had a disc cyst. The cyst was located in the ventrolateral epidural space. On T2-weighted images, the migrated disc fragment returned a higher signal than the disc of origin in 6 of 7 patients. The disc cyst returned a signal similar to that of cerebrospinal fluid. The MR appearances of disc fragments can be puzzling, particularly if they are located in the posterior epidural space. It is important to recognize the abnormalities in order to differentiate them from less common lesions such as hematoma, abscess and neurinoma. (orig.)

  12. Imaging characteristics of noncontained migrating disc fragment and cyst

    Energy Technology Data Exchange (ETDEWEB)

    Eerens, I.; Demaerel, P.; Haven, F.; Wilms, G. [Dept. of Radiology, University Hospitals, Leuven (Belgium); Loon, J. van; Calenbergh, F. van [Dept. of Neurosurgery, University Hospitals, Leuven (Belgium)

    2001-05-01

    The purpose of this article is to review less common presentations of degenerative disc disease on MR imaging. The images of eight patients were retrospectively analyzed. Six of them had transligamentous (or noncontained) disc herniations, the fragments of which were located in the posterior epidural space in three of them. One patient had a transdural disc fragment and one patient had a disc cyst. The cyst was located in the ventrolateral epidural space. On T2-weighted images, the migrated disc fragment returned a higher signal than the disc of origin in 6 of 7 patients. The disc cyst returned a signal similar to that of cerebrospinal fluid. The MR appearances of disc fragments can be puzzling, particularly if they are located in the posterior epidural space. It is important to recognize the abnormalities in order to differentiate them from less common lesions such as hematoma, abscess and neurinoma. (orig.)

  13. Relationship of condylar position to disc position and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Incesu, L.; Taskaya-Yilmaz, N. E-mail: nergizy@omu.edu.tr; Oeguetcen-Toller, M.; Uzun, E

    2004-09-01

    Introduction/objective: The purpose of this study was to assess whether condylar position, as depicted by magnetic resonance imaging, was an indicator of disc morphology and position. Methods and material: One hundred and twenty two TMJs of 61 patients with temporomandibular joint disorder were examined. Condylar position, disc deformity and degree of anterior disc displacement were evaluated by using magnetic resonance imaging. Results and discussion: Posterior condyle position was found to be the main feature of temporomandibular joints with slight and moderate anterior disc displacement. No statistical significance was found between the condylar position, and reducing and nonreducing disc positions. On the other hand, superior disc position was found to be statistically significant for centric condylar position. Conclusion: It was concluded that posterior condyle position could indicate anterior disc displacement whereas there was no relation between the position of condyle and the disc deformity.

  14. Angiogenesis in the degeneration of the lumbar intervertebral disc

    OpenAIRE

    David, Gh; Ciurea, AV; Iencean, SM; Mohan, A

    2010-01-01

    The goal of the study is to show the histological and biochemical changes that indicate the angiogenesis of the intervertebral disc in lumbar intervertebral disc hernia and the existence of epidemiological correlations between these changes and the risk factors of lumbar intervertebral disc hernia, as well as the patient's quality of life (QOL). We have studied 50 patients aged between 18 and 73 years old, who have undergone lumbar intervertebral disc hernia surgery, making fibroblast growth ...

  15. On the diversity and statistical properties of protostellar discs

    Science.gov (United States)

    Bate, Matthew R.

    2018-04-01

    We present results from the first population synthesis study of protostellar discs. We analyse the evolution and properties of a large sample of protostellar discs formed in a radiation hydrodynamical simulation of star cluster formation. Due to the chaotic nature of the star formation process, we find an enormous diversity of young protostellar discs, including misaligned discs, and discs whose orientations vary with time. Star-disc interactions truncate discs and produce multiple systems. Discs may be destroyed in dynamical encounters and/or through ram-pressure stripping, but reform by later gas accretion. We quantify the distributions of disc mass and radii for protostellar ages up to ≈105 yr. For low-mass protostars, disc masses tend to increase with both age and protostellar mass. Disc radii range from of order 10 to a few hundred au, grow in size on time-scales ≲ 104 yr, and are smaller around lower mass protostars. The radial surface density profiles of isolated protostellar discs are flatter than the minimum mass solar nebula model, typically scaling as Σ ∝ r-1. Disc to protostar mass ratios rarely exceed two, with a typical range of Md/M* = 0.1-1 to ages ≲ 104 yr and decreasing thereafter. We quantify the relative orientation angles of circumstellar discs and the orbit of bound pairs of protostars, finding a preference for alignment that strengths with decreasing separation. We also investigate how the orientations of the outer parts of discs differ from the protostellar and inner disc spins for isolated protostars and pairs.

  16. INJURIES IN DISC GOLF - A DESCRIPTIVE CROSS-SECTIONAL STUDY

    DEFF Research Database (Denmark)

    Rahbek, Martin Amadeus; Nielsen, Rasmus Oestergaard

    2016-01-01

    BACKGROUND: Disc golf is rapidly increasing in popularity and more than two million people are estimated to regularly participate in disc golf activities. Despite this popularity, the epidemiology of injuries in disc golf remains under reported. PURPOSE: The purpose of the present study was to in......BACKGROUND: Disc golf is rapidly increasing in popularity and more than two million people are estimated to regularly participate in disc golf activities. Despite this popularity, the epidemiology of injuries in disc golf remains under reported. PURPOSE: The purpose of the present study...... was to investigate the prevalence and anatomic distribution of injuries acquired through disc-golf participation in Danish disc golf players. METHODS: The study was a cross-sectional study conducted on Danish disc-golf players. In May 2015, invitations to complete a web-based questionnaire were spread online via...... social media, and around disc-golf courses in Denmark. The questionnaire included questions regarding disc-golf participation and the characteristics of injuries acquired through disc golf participation. The data was analyzed descriptively. RESULTS: An injury prevalence of 13.3% (95% CI: 6.7% to 19...

  17. On the illumination of neutron star accretion discs

    Science.gov (United States)

    Wilkins, D. R.

    2018-03-01

    The illumination of the accretion disc in a neutron star X-ray binary by X-rays emitted from (or close to) the neutron star surface is explored through general relativistic ray tracing simulations. The applicability of the canonical suite of relativistically broadened emission line models (developed for black holes) to discs around neutron stars is evaluated. These models were found to describe well emission lines from neutron star accretion discs unless the neutron star radius is larger than the innermost stable orbit of the accretion disc at 6 rg or the disc is viewed at high inclination, above 60° where shadowing of the back side of the disc becomes important. Theoretical emissivity profiles were computed for accretion discs illuminated by hotspots on the neutron star surfaces, bands of emission and emission by the entirety of the hot, spherical star surface and in all cases, the emissivity profile of the accretion disc was found to be well represented by a single power law falling off slightly steeper than r-3. Steepening of the emissivity index was found where the emission is close to the disc plane and the disc can appear truncated when illuminated by a hotspot at high latitude. The emissivity profile of the accretion disc in Serpens X-1 was measured and found to be consistent with a single unbroken power law with index q=3.5_{-0.4}^{+0.3}, suggestive of illumination by the boundary layer between the disc and neutron star surface.

  18. Time Localisation of Surface Defects on Optical Discs

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Wickerhauser, M.V.

    Many have experienced problems with their Compact Disc player when a disc with a scratch or a finger print is tried played. One way to improve the playability of discs with such a defect, is to locate the defect in time and then handle it in a special way. As a consequence this time localisation...

  19. Time Localisation of Surface Defects on Optical Discs

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Wickerhauser, M.V.

    2004-01-01

    Many have experienced problems with their Compact Disc Player when a disc with a scratch or a fingerprint is tried played. One way to improve the playability of discs with such a defect, is to locate the defect in time and then handle it in a special way. As a consequence this time localization...

  20. Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation.

    Science.gov (United States)

    Lee, Jung Hwan; Lee, Sang-Ho

    2016-02-01

    Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more

  1. Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation

    Science.gov (United States)

    Lee, Jung Hwan; Lee, Sang-Ho

    2016-01-01

    Abstract Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more

  2. [Low back pain and degenerative disc disease].

    Science.gov (United States)

    Jandrić, Slavica; Antić, Branislav

    2006-01-01

    Various clinical conditions can cause low back pain, and in most cases it is of a degenerative origin. Degenerative disc disease is a common condition which affects young to middle-aged men and women equally. Changes in the mechanical properties of the disc lead to degenerative arthritis in the intervertebral joints, osteophytes, and narrowing the intervertebral foramen or the spinal canal. Degenerative cascade, described by Kirkaldy-Willis, is the widely accepted pathophysiologic model describing the degenerative process as it affects the lumbar spine in 3 phases. There are two forms of low back pain secondary to degenerative disc disease: a) lumbalgia and b) lumbar radiculopathy. Limitation of movement, problems with balance, pain, loss of reflexes in the extremities, muscle weakness, loss of sensation or other signs of neurological damage can be found on physical examination. For accurate diagnosis, it is often necessary to combine clinical examination and sophisticated technology. Coservative treatment consists of rest, physical therapy, pharmacological therapy and injection therapy. Physical rehabilitation with active patient participation is a key approach to treatment of patients with discogenic pain. Physical therapy, occupational therapy and kinesitherapy are important for improving muscle strength, endurance, and flexibility. Disc surgery is performed if surgical intervention is required.

  3. Can Exercise Positively Influence the Intervertebral Disc?

    NARCIS (Netherlands)

    Belavý, Daniel L.; Albracht, Kirsten; Bruggemann, Gert Peter; Vergroesen, Pieter Paul A; van Dieën, Jaap H.

    2016-01-01

    To better understand what kinds of sports and exercise could be beneficial for the intervertebral disc (IVD), we performed a review to synthesise the literature on IVD adaptation with loading and exercise. The state of the literature did not permit a systematic review; therefore, we performed a

  4. Grand Challenges in Protoplanetary Disc Modelling

    NARCIS (Netherlands)

    Haworth, Thomas J.; Ilee, John D.; Forgan, Duncan H.; Facchini, Stefano; Price, Daniel J.; Boneberg, Dominika M.; Booth, Richard A.; Clarke, Cathie J.; Gonzalez, Jean-François; Hutchison, Mark A.; Kamp, Inga; Laibe, Guillaume; Lyra, Wladimir; Meru, Farzana; Mohanty, Subhanjoy; Panić, Olja; Rice, Ken; Suzuki, Takeru; Teague, Richard; Walsh, Catherine; Woitke, Peter; authors, Community

    2016-01-01

    The Protoplanetary Discussions conference-held in Edinburgh, UK, from 2016 March 7th-11th-included several open sessions led by participants. This paper reports on the discussions collectively concerned with the multi-physics modelling of protoplanetary discs, including the self-consistent

  5. Geršgorin discs revisited

    Czech Academy of Sciences Publication Activity Database

    Fiedler, Miroslav; Hall, F.J.; Marsli, R.

    2013-01-01

    Roč. 438, č. 1 (2013), s. 598-603 ISSN 0024-3795 Institutional support: RVO:67985807 Keywords : geometric multiplicity * algebra ic multiplicity * Geršgorin disc Subject RIV: BA - General Mathematics Impact factor: 0.983, year: 2013

  6. Inflammatory profiles in canine intervertebral disc degeneration

    NARCIS (Netherlands)

    Willems, Nicole; Tellegen, Anna R; Bergknut, Niklas; Creemers, Laura B; Wolfswinkel, Jeannette; Freudigmann, Christian; Benz, Karin; Grinwis, Guy C M; Tryfonidou, Marianna A; Meij, Björn P

    2016-01-01

    BACKGROUND: Intervertebral disc (IVD) disease is a common spinal disorder in dogs and degeneration and inflammation are significant components of the pathological cascade. Only limited studies have studied the cytokine and chemokine profiles in IVD degeneration in dogs, and mainly focused on gene

  7. Intervertebral disc herniation: prevalence and association with ...

    African Journals Online (AJOL)

    Method: A total of 120 adult patients who came for magnetic resonance imaging scan of the lumbosacral spine for a period of 1year in the department of Radiology University of Port-Harcourt Teaching Hospital. The end plates of 600 lumbar interspaces were graded for type, size and site of lumbar disc herniation. Results: ...

  8. Solid angle subtended by two circular discs

    International Nuclear Information System (INIS)

    Gilly, Louis.

    1978-09-01

    Methods of calculation of solid angles, subtended by two circular discs are analysed. Calculus are methodically classified as follow: series development Legendre polynomes, defined integral, elliptic integrals, Bessel integrals, multiple integrals, Monte Carlo method, electrostatic analogy. Applications in Nuclear Physics are added as examples. List of numeric tables completes bibliography [fr

  9. Fusion around cervical disc prosthesis: case report.

    NARCIS (Netherlands)

    Bartels, R.H.M.A.; Donk, R.

    2005-01-01

    OBJECTIVE AND IMPORTANCE: Cervical arthroplasty is a relatively new method to maintain motion after cervical anterior discectomy. Two cases are presented in which bony fusion occurred around a cervical disc prosthesis. CLINICAL PRESENTATION: A 30-year-old man and a 49-year-old woman underwent a

  10. Colloidal discs in nematic liquid crystals

    International Nuclear Information System (INIS)

    Silvestre, N M; Patricio, P; Tasinkevych, M; Andrienko, D; Gama, M M Telo da

    2004-01-01

    We use adaptive finite elements methods to investigate a variety of structures in inverted nematic emulsions numerically. In particular, we study dipolar and quadrupolar interactions between colloidal discs in two-dimensional nematics. The behaviour of colloidal particles near a substrate and at a nematic-isotropic interface are also considered

  11. The global structure of galactic discs

    NARCIS (Netherlands)

    Grijs, R. de

    1998-01-01

    A statistical study of global galaxy parameters can help to improve our understanding of galaxy formation processes. In this paper we present the analysis of global galaxy parameters based on optical and near-infrared observations of a large sample of edge-on disc galaxies. We found a correlation

  12. CT in diagnosis of recurrent vertebral disc hernias after preceding lumbar disc prolapse surgery

    International Nuclear Information System (INIS)

    Burval, S.; Nekula, J.; Vaverka, M.; Veliskova, J.

    1992-01-01

    20 patients with recurrent symptoms following operations for disc prolapse and resistant to treatment were studied by CT, using plain and enhanced images. The results have been analysed. In 10 patients a recurrence of disc prolapse was diagnosed, and this was confirmed surgically in 8 cases. In 2 patients there was epidural scarring. The findings indicate that differential diagnosis between scarring and recurring prolapse can by accurately made by this technique. (orig.) [de

  13. Transplantation of dedifferentiation fat cells promotes intervertebral disc regeneration in a rat intervertebral disc degeneration model.

    Science.gov (United States)

    Nakayama, Enshi; Matsumoto, Taro; Kazama, Tomohiko; Kano, Koichiro; Tokuhashi, Yasuaki

    2017-11-18

    Our group has reported that mature adipocyte-derived dedifferentiated fat (DFAT) cells show multilineage differentiation potential similar to that observed in mesenchymal stem cells. In the present study, we examined whether DFAT cell transplantation could contribute to intervertebral disc regeneration using a rat intervertebral disc degeneration (IDD) model. The IDD was created in Sprague-Dawley rats by puncturing at level of caudal intervertebral disc under fluoroscopy. One week after injury, rat DFAT cells (5 × 10 4 , DFAT group, n = 13) or phosphate-buffered saline (PBS, control group, n = 13) were injected into the intervertebral disc. Percent disc height index (%DHI) was measured every week and histology of injured disc was evaluated at 8 weeks after transplantation. Radiographic analysis revealed that the %DHI in the DFAT group significantly higher than that in the control group at 2-3 weeks after transplantation. Histological analysis revealed that ectopic formation of nucleus pulposus (NP)-like tissue at the outer layer of annulus fibrosus was frequently observed in the DFAT group but not in the control group. Transplantation experiments using green fluorescent protein (GFP)-labeled DFAT cells revealed that the ectopic NP-like tissue was positive for GFP, suggesting direct differentiation of DFAT cells into NP-like cells. In conclusion, DFAT cell transplantation promoted the regeneration of intervertebral disc and improved intervertebral disc height in the rat IDD model. Because adipose tissue is abundant and easily accessible, DFAT cell transplantation may be an attractive therapeutic strategy against IDD. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  14. [Efficacy of percutaneous laser disc decompression for radiculalgia due to lumbar disc hernia (149 patients)].

    Science.gov (United States)

    Morelet, Aude; Boyer, François; Vitry, Fabien; Ackah-Miezan, Stanley; Berquet, Renaud; Langlois, Sandrine; Brochot, Pascal; Breidt, Damien; Eschard, Jean-Paul; Etienne, Jean-Claude

    2007-11-01

    To assess the efficacy of percutaneous laser disc decompression for patients with radicular pain due to lumbar disc hernia and to identify factors that may predict outcome. The study included all patients treated with percutaneous laser disc decompression from May 2003 through May 2005 at Reims University Hospital and the Courlancy Clinic of Reims. Each patient had previous undergone at least six weeks of conventional medical treatment. The same technique, with either a laser diode or Nd: YAG, was used under endoscopic control and with neuroleptanalgesia. They were seen at 1, 3, 6 and 12 months. The principal evaluation criteria were the course of radicular pain, return to work, and need for surgery. We reexamined 149 patients 1 month after the procedure, 135 after 3 months, 102 after 6 months and 59 a year after the procedure. At a month after surgery, radicular pain had decreased by at least half, and sometimes even completely disappeared in 63.1% of patients at 1 month, 66.6% at 3 months, 73.5% at 6 months, and 83.1% at 12 months, while 24%, 50,4%, 61.2%, and 67.3%, respectively, had returned to work. No patient had serious complications. Finally, 45 of the 149 (30.2%) patients chose to have a traditional surgical procedure after percutaneous laser disc decompression. Percutaneous laser disc decompression is effective, noninvasive and well tolerated for patients with radicular pain due to lumbar disc hernia.

  15. The diagnosis of internal disc disruption with CT discography

    International Nuclear Information System (INIS)

    Liu Miao; Chen Xingcan; Li Xiaohong; Pan Yongqin

    2008-01-01

    Objective: To study the value of diagnosis for internal disc disruption (IDD)with CT discography(CTD). Methods: 42 discs of 32 patients showing no disc herniation on CT or MRI, but suffering from chronic low back pain, were undertaken CTD to work out the types of CTD with correlation between contrast medium dosages and the induction of pain. Results: CTD demonstrated 4 types of IDD which was individually correlated with the contrast dosages and induced pain; furthermore the dosages for positive and negative disc cases showed significant differece (P<0.01). Conclusions: CTD can show the direct sign of internal disc disruption, providing more information than conventional discography. (authors)

  16. Fas ligand exists on intervertebral disc cells: a potential molecular mechanism for immune privilege of the disc.

    Science.gov (United States)

    Takada, Toru; Nishida, Kotaro; Doita, Minoru; Kurosaka, Masahiro

    2002-07-15

    Rat and human intervertebral disc specimens were examined immunohistochemically. Reverse transcription polymerase chain reaction (RT-PCR) analysis was also performed on rat disc tissue to demonstrate the existence of Fas ligand. To clarify the existence of Fas ligand on intact intervertebral disc cells. The nucleus pulposus has been reported to be an immune-privileged site. The immune-privileged characteristic in other tissues such as the retina and testis has been attributed to the local expression of Fas ligand, which acts by inducing apoptosis of invading Fas-positive T-cells. The existence of Fas ligand in normal disc cells has not yet been addressed. Skeletally mature SD male rats were killed, and the coccygeal discs were harvested. Human disc specimens were obtained from idiopathic scoliosis patients during surgical procedures. Immunohistochemical staining for Fas ligand was performed for cross-sections of the discs by standard procedures. Reverse transcription polymerase chain reaction analysis was also carried out to demonstrate Fas ligand mRNA expression on rat intervertebral discs. Testes of the rats were used for positive controls, and muscles were used for negative controls. The sections were observed by light microscopy. The nucleus pulposus cells exhibited intense positive immune staining for Fas ligand. The outer anulus fibrosus cells and notochordal cells exhibited little immunopositivity. The positive controls exhibited positive immune staining, and the negative control showed no immunopositivity. The result of RT-PCR confirmed the existence of Fas ligand in disc cells. The human nucleus pulposus cells showed a similar predilection to rat disc cells. We demonstrated the existence of Fas ligand on disc cells, which should play a key role in the potential molecular mechanism to maintain immune privilege of the disc. Immune privilege and Fas ligand expression of the intervertebral disc may provide a new insight for basic science research as well as

  17. MR image assessment of disc configuration and degree of anterior disc displacement in internal derangement related to age

    Energy Technology Data Exchange (ETDEWEB)

    Igarashi, Chinami; Kobayashi, Kaoru; Imanaka, Masahiro; Yuasa, Masao; Yamamoto, Akira [Tsurumi Univ., Yokohama (Japan). School of Dental Medicine

    1999-03-01

    This study was designed to evaluate the configuration of the articular disc and degree of anterior disc displacement on magnetic resonance (MR) imagings in temporomandibular joints (TMJs) with internal derangement. A total of 363 joints diagnosed as having anterior disc displacement with reduction (ADD w R) and 523 joints diagnosed as having anterior disc displacement without reduction (ADD wo R) by MR imaging were examined. These joints did not show severe osseous changes on the condylar head or glenoid fossa. We assessed the configuration of the articular disc and degree of anterior disc displacement. In the ADD w R group, 82.6% of the articular discs showed biconcave configuration; enlargement of the posterior band in 4.6%, biconvex configuration in 0.5%, and others in 10.7%. Moreover 62.5% of the discs showed a slight degree of anterior disc displacement; were 27.2% moderately displaced and were 10.2% severe displaced. The prevalence of slightly displaced discs was higher in the TMJs of cases over 50 years of age than in cases under 30 years in the ADD w R group. On the other hand, in the ADD wo R group 35.9% of the articular discs showed biconcave configuration; enlargement of the posterior band in 12.6%, biconvex configuration in 25.4%, and others in 22.3%. Furthermore, 4.4% of the discs were slightly displaced; 43.9% moderately displaced and 51.6% were severely displaced. The prevalence of severely displaced and deformed discs in joints of cases over 40 years of age was high in the ADD wo R group. The prevalence of slightly displaced biconcave discs was higher in the ADD w R group. The other hand, the prevalence of severely displaced deformed discs was higher in the ADD wo R group. MR findings of internal derangement of the TMJ were found to be significantly correlated with age. (author)

  18. Be discs in binary systems - II. Misaligned orbits

    Science.gov (United States)

    Cyr, I. H.; Jones, C. E.; Panoglou, D.; Carciofi, A. C.; Okazaki, A. T.

    2017-10-01

    We use a smoothed particle hydrodynamics (SPH) code to examine the effects of misaligned binary companions on Be star discs. We systematically vary the degree of misalignment between the disc and the binary orbit, as well as the disc viscosity and orbital period to study their effects on the density in the inner and outer parts of the disc. We find that varying the degree of misalignment, the viscosity and the orbital period affects both the truncation radius and the density structure of the outer disc, while the inner disc remains mostly unaffected. We also investigate the tilting of the disc in the innermost part of the disc and find the tilt increases with radius until reaching a maximum around 5 stellar radii. The direction of the line of nodes, with respect to the equator of the central star, is found to be offset compared to the orbital line of nodes, and to vary periodically in time, with a period of half a orbital phase. We also compare the scaleheight of our discs with the analytical scaleheight of an isothermal disc, which increases with radius as r1.5. We find that this formula reproduces the scaleheight well for both aligned and misaligned systems but underestimates the scaleheight in regions of the disc where density enhancements develop.

  19. Clinical study of CT discography for the lumbar disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Tadashi (Yamaguchi Univ., Ube (Japan). School of Medicine)

    1990-08-01

    The purpose of this clinical study was to introduce technique for correct positioning of the needle into the center of the disc for discography by means of CT analysis and also to clarify usefulness of CT discography for diagnosis of the lumbar disc herniation. We have taken CT analysis in order to determine correct place and the angle of inserting the needle. This measurement provides easy needle insertion. Unless the needle tip places center of disc, discogram false positive or negative will occur as a result. The materials of this study are 222 discs of 105 cases with the lumbar disc herniation. Comparative study of the findings among myelography, discography and CT discography was investigated. The results indicated that CT discography demonstrates the most clear findings and is useful in the diagnosis of lumbar disc herniation, especially in obtaining detailed observation of herniated discs. (author).

  20. Computer assisted characterization of cervical intervertebral disc degeneration in MRI

    Science.gov (United States)

    Michopoulou, S.; Boniatis, I.; Costaridou, L.; Cavouras, D.; Panagiotopoulos, E.; Panayiotakis, G.

    2009-05-01

    A texture-based pattern recognition system is proposed for the automatic characterization of cervical intervertebral disc degeneration from saggital magnetic resonance images of the spine. A case sample of 50 manually segmented ROIs, corresponding to 25 normal and 25 degenerated discs, was analyzed and textural features were generated from each disc-ROI. Student's t-test verified the existence of statistically significant differences between textural feature values generated from normal and degenerated discs. This finding is indicative of disc image texture differentiation due to the degeneration of the disc. The generated features were employed in the design of a pattern recognition system based on the Least Squares Minimum Distance classifier. The system achieved a classification accuracy of 94{%} and it may be of value to physicians for the assessment of cervical intervertebral disc degeneration in MRI.

  1. Examination of turbine discs from nuclear power plants

    International Nuclear Information System (INIS)

    Czajkowski, C.J.; Weeks, J.R.

    1982-01-01

    Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station, and on two failed turbine discs (governor and generator ends) from the Yankee-Rowe Nuclear Power Station. Cooper is a boiling water reactor (BWR) which went into commercial operation in July 1974, and Yankee-Rowe is a pressurized water reactor (PWR) which went into commercial operation in June 1961. Cracks were identified in the bore of the Cooper disc after 41,913 hours of operation, and the disc removed for repair. At Yankee-Rowe two discs failed after 100,000 hours of operation. Samples of the Cooper disc and both Yankee-Rowe disc (one from the governor and one from the generator end of the LP turbine) were sent to Brookhaven National Laboratory (BNL) for failure analysis

  2. Global Dynamics of Shaft Lines Rotating in Surrounding Fluids Application to Thin Fluid Films

    Directory of Open Access Journals (Sweden)

    David Lornage

    2004-01-01

    a disc and a thin-walled shaft mounted on a hydrodynamic bearing. The second is intended for studying a more realistic structure composed of a shaft and a wheel coupled with a fluid film between the wheel and a casing. These applications make it possible to identify trends related to fluid effects and couplings between the flexible structural parts.

  3. Queixas auditivas de disc jockeys da cidade de Recife Auditory complaints in disc jockeys in Recife

    Directory of Open Access Journals (Sweden)

    Eliza Maia de Britto Macedo

    2011-06-01

    Full Text Available OBJETIVO: investigar a ocorrência de queixas auditivas em disc jockeys da cidade de Recife/PE. MÉTODOS: foi realizada uma entrevista com 30 disc jockeys, com idade entre 19 e 28 anos, abordando informações ocupacionais, conhecimentos gerais sobre o ruído e queixas auditivas (diminuição da acuidade auditiva, desconforto a sons intensos, zumbido, sensação de ouvido abafado e otalgia. A análise foi realizada por meio de abordagem quantitativa, utilizando o teste estatístico t-student. RESULTADOS: dentre os dados mais relevantes, destacam-se: 46,7% dos disc jockeys apresentaram, espontaneamente, queixas auditivas, em especial, a diminuição da acuidade auditiva (relatada por todos os sujeitos; 14 disc jockeys (46,67% referiram desconforto a sons intensos e 13 (43,33% mencionaram zumbido. Todos afirmaram ter conhecimento sobre os riscos do ruído para a saúde auditiva, mas 76,7% não realizam qualquer medida preventiva de suas consequências. A perda auditiva foi referida pelos sujeitos como o principal risco da exposição a níveis intensos de pressão sonora. CONCLUSÃO: todos os disc jockeys apresentaram queixa de perda auditiva e, entre as demais queixas auditivas, destacaram-se o desconforto a sons intensos e o zumbido. Tendo em vista a irreversibilidade da perda auditiva induzida por elevados níveis de pressão sonora, os disc jockeys devem ser periodicamente avaliados a fim de que se confirme ou não a perda auditiva de que se queixaram e, caso ela exista, deve ser monitorada para que seja passível de intervenção pelo fonoaudiólogo. Desta forma, percebe-se a necessidade de atuação da Fonoaudiologia junto aos disc jockeys, uma vez que poder-se-á propiciar a otimização do exercício profissional com o mínimo de risco possível.PURPOSE: to investigate the occurrence of auditory complaints in disc jockeys from the city of Recife/PE. METHODS: an interview was carried through with 30 disc jockeys aged between 19 and 48 years

  4. Total disc replacement for chronic back pain in the presence of disc degeneration.

    Science.gov (United States)

    Jacobs, Wilco; Van der Gaag, Niels A; Tuschel, Alexander; de Kleuver, Marinus; Peul, Wilco; Verbout, A J; Oner, F Cumhur

    2012-09-12

    In the search for better surgical treatment of chronic low-back pain (LBP) in the presence of disc degeneration, total disc replacement has received increasing attention in recent years. A possible advantage of total disc replacement compared with fusion is maintained mobility at the operated level, which has been suggested to reduce the chance of adjacent segment degeneration. The aim of this systematic review was to assess the effect of total disc replacement for chronic low-back pain in the presence of lumbar disc degeneration compared with other treatment options in terms of patient-centred improvement, motion preservation and adjacent segment degeneration. A comprehensive search in Cochrane Back Review Group (CBRG) trials register, CENTRAL, MEDLINE, EMBASE, BIOSIS, ISI, and the FDA register was conducted. We also checked the reference lists and performed citation tracking of included studies. We included randomised controlled trials (RCTs) comparing total disc replacement with any other intervention for degenerative disc disease. We assessed risk of bias per study using the criteria of the CBRG. Quality of evidence was graded according to the GRADE approach. Two review authors independently selected studies and assessed risk of bias of the studies. Results and upper bounds of confidence intervals were compared against predefined clinically relevant differences. We included 40 publications, describing seven unique RCT's. The follow-up of the studies was 24 months, with only one extended to five years. Five studies had a low risk of bias, although there is a risk of bias in the included studies due to sponsoring and absence of any kind of blinding. One study compared disc replacement against rehabilitation and found a statistically significant advantage in favour of surgery, which, however, did not reach the predefined threshold for clinical relevance. Six studies compared disc replacement against fusion and found that the mean improvement in VAS back pain was

  5. Thermophoretic aggregation of particles in a protoplanetary disc

    Science.gov (United States)

    Smith, Francis J.

    2018-04-01

    Thermophoresis causes particles to move down a temperature gradient to a cooler region of a neutral gas. An example is the temperature gradient in the gas around a large cold object, such as an aggregate of particles, cooled by radiation in a protoplanetary disc. Particles near this aggregate move down the temperature gradient to the aggregate, equivalent to the particles being attracted to it by an inter-particle thermophoretic force. This force is proportional to the temperature difference between gas and aggregate, to the gas density and to the cross-section of the aggregate. The force can be large. For example, calculations based on the equations of motion of the interacting particles show that it can be large enough in an optically thin environment to increase the rate of aggregation by up to six orders of magnitude when an aggregate radius lies between 0.1 μm and 1 mm. From 1 mm to about 10 cm aggregates drift inwards through the gas too quickly for the thermophoretic attraction to increase aggregation significantly; so they grow slowly, causing an observed accumulation of particles at these sizes. Particles above 10 cm move more quickly, causing aggregation due to collisions, but also causing fragmentation. However, calculations show that fragmenting particles and bouncing particles in inelastic collisions often have low enough relative velocities that thermophoresis brings them together again. This allows particles to grow above 1 m, which is otherwise difficult to explain.

  6. Low back pain associated with lumbar disc herniation: role of moderately degenerative disc and annulus fibrous tears

    Science.gov (United States)

    Yang, Hao; Liu, Hui; Li, Zemin; Zhang, Kuibo; Wang, Jianru; Wang, Hua; Zheng, Zhaomin

    2015-01-01

    Lumbar disc herniation is one of the most common spinal degenerative disorders which may lead to low back pain (LBP) and radicular leg pain. However, it remains difficult to diagnose a degenerative herniated disc as the LBP generator in clinical practice. The purpose of this study is to explore the characteristic changes of a herniated disc causing LBP on MRI and to clarify the underlying role of inflammatory mediators and annulus fibrous (AF) tears in LBP generation associated with disc herniation. We prospectively collected intervertebral disc specimens and MRI from 57 single-segment disc herniation patients with radiculopathy. All subjects were grouped according to LBP occurrence or disc degeneration severity for the comparison of inflammatory mediators’ expression and AF tears occurrence (High Intensity Zone, HIZ, on MRI). LBP incidence under circumstances of different degeneration severity with or without HIZ was further analyzed. Both LBP incidence and Inflammatory mediators expression in moderately degenerated group was higher than mildly and severely degenerative groups. HIZ incidence was higher in moderately and severely degenerated groups. LBP incidence in the patients with both moderately degenerated discs and HIZ was 86.7%, much higher than the rest of the patient population. In conclusion, the high expression of inflammatory mediators with AF tears causes LBP associated with disc herniation. Moderately degenerative disc with HIZ is MRI morphological change of herniated disc causing LBP, which can be applied to diagnose LBP. PMID:25932092

  7. Optic disc and peripapillary retinal nerve fiber layer characteristics associated with glaucomatous optic disc in young myopia.

    Science.gov (United States)

    Lee, Jong Eun; Sung, Kyung Rim; Park, Ji Min; Yoon, Joo Young; Kang, Sung Yong; Park, Sung Bae; Koo, Hyung Jin

    2017-03-01

    To explore optic disc and peripapillary retinal nerve fiber layer (RNFL) features associated with glaucomatous optic disc (GOD) in young myopia. Presence of GOD, optic disc tilt, and disc torsion were determined using fundus photographs. If the measured disc tilt ratio was >1.3, the optic disc was classified as tilted. Optic disc torsion was defined as a >15° deviation in the long axis of the optic disc from the vertical meridian. The average and four quadrants RNFL thicknesses were assessed using spectral domain optical coherence tomography (SD-OCT). Logistic regression analyses were performed to identify factors associated with the presence of GOD. Nine hundred and sixty myopic subjects were recruited from four refractive surgery clinic databases. The mean age was 26.6 ± 5.7 years and spherical equivalent (SE) was -5.5 ± 2.5 diopters. Among 960 eyes, 26 (2.7%) received GOD group classification. Among 934 normal eyes, 290 (31.0%) had titled optic discs. Eighteen eyes (69.2%) in the GOD group had tilted optic discs. When compared to normal eyes, the GOD group had significantly higher tilt ratios (1.4 ± 0.2 vs. 1.2 ± 0.1, p Optic disc tilt was found in approximately one-third of young myopic eyes and was independently associated with the presence of GOD.

  8. The occurrence and regional distribution of DR4 on herniated disc cells: a potential apoptosis pathway in lumbar intervertebral disc.

    Science.gov (United States)

    Zhang, Liang; Niu, Tao; Yang, Shang-You; Lu, Zhenhua; Chen, Bohua

    2008-02-15

    Intervertebral discs surgically obtained from 60 herniated patients and 5 normal individuals were examined to correlate the regional distribution of DR4-receptor and apoptosis. To explore the role of a tumor necrosis factor superfamily member DR4 and the TRAIL/DR4 mediated apoptosis in the human lumbar intervertebral disc. The pathogenesis of lumbar degenerative intervertebral discs remains not completely understood. In herniated lumbar disc tissues, increased apoptosis and higher expression of Fas/Fas ligand and caspase-3 have been reported, suggesting a pivotal role of apoptotic mechanisms in intervertebral disc degeneration. However, it is not clear that apoptosis mediators such as TRAIL and Death Receptor 4 (DR4), which often represent different apoptosis signal pathways, contribute to the apoptosis process during the development of the degenerated intervertebral discs. Apoptosis was determined by poly(ADP-ribose) polymerase (PARP) p85 immunohistochemistry. Expression of DR4 was revealed by immunohistochemistry analysis. Statistical difference among groups was analyzed using one-way ANOVA with LSD post hoc multiple comparisons and the bivariate correlations. Apoptotic cells were detected in the nucleus pulposus and anulus fibrosus of all samples. However, the number of apoptotic cells was significantly higher in the nucleus compared with the anulus. Further, there were significantly more apoptotic cells in the herniated discs compared with the normal discs. Within herniated discs, a remarkably higher percentage of positive staining cells were detected in the uncontained discs than the contained ones. Strong expression of DR4 was detected in all samples of degenerative herniated discs, whereasmuch weaker expression was sporadically identified in normal discs. In addition, the prevalence of apoptosis positively correlated with the severity of disc degeneration. The concomitant increase of DR4 expression in the regions of heavy apoptotic cell aggregation suggests

  9. Material Science in Cervical Total Disc Replacement.

    Science.gov (United States)

    Pham, Martin H; Mehta, Vivek A; Tuchman, Alexander; Hsieh, Patrick C

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation.

  10. Cervical disc arthroplasty: Pros and cons.

    Science.gov (United States)

    Moatz, Bradley; Tortolani, P Justin

    2012-01-01

    Cervical disc arthroplasty has emerged as a promising potential alternative to anterior cervical discectomy and fusion (ACDF) in appropriately selected patients. Despite a history of excellent outcomes after ACDF, the question as to whether a fusion leads to adjacent segment degeneration remains unanswered. Numerous US investigational device exemption trials comparing cervical arthroplasty to fusion have been conducted to answer this question. This study reviews the current research regarding cervical athroplasty, and emphasizes both the pros and cons of arthroplasty as compared with ACDF. Early clinical outcomes show that cervical arthroplasty is as effective as the standard ACDF. However, this new technology is also associated with an expanding list of novel complications. Although there is no definitive evidence that cervical disc replacement reduces the incidence of adjacent segment degeneration, it does show other advantages; for example, faster return to work, and reduced need for postoperative bracing.

  11. Material Science in Cervical Total Disc Replacement

    Science.gov (United States)

    Pham, Martin H.; Mehta, Vivek A.; Tuchman, Alexander; Hsieh, Patrick C.

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281

  12. Material Science in Cervical Total Disc Replacement

    Directory of Open Access Journals (Sweden)

    Martin H. Pham

    2015-01-01

    Full Text Available Current cervical total disc replacement (TDR designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti, and cobalt-chrome (CoCr. These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation.

  13. MR imaging of degenerative disc disease

    Energy Technology Data Exchange (ETDEWEB)

    Farshad-Amacker, Nadja A., E-mail: nadja.farshad@usz.ch [Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich (Switzerland); Farshad, Mazda [Department of Orthopaedic Surgery, Balgrist University Hospital, Zurich (Switzerland); Winklehner, Anna; Andreisek, Gustav [Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich (Switzerland)

    2015-09-15

    Highlights: • This systematic literature review summarizes the current knowledge on MR imaging in degenerative disc disease. • Different classification systems for segmental spine degeneration are summarized. • It outlines the diagnostic limitations of MR imaging. - Abstract: Magnet resonance imaging (MRI) is the most commonly used imaging modality for diagnosis of degenerative disc disease (DDD). Lack of precise observations and documentation of aspects within the complex entity of DDD might partially be the cause of poor correlation of radiographic findings to clinical symptoms. This literature review summarizes the current knowledge on MRI in DDD and outlines the diagnostic limitations. The review further sensitizes the reader toward awareness of potentially untended aspects of DDD and the interaction of DDD and endplate changes. A summary of the available classifications for DDD is provided.

  14. Inflammation in intervertebral disc degeneration and regeneration

    Science.gov (United States)

    Molinos, Maria; Almeida, Catarina R.; Caldeira, Joana; Cunha, Carla; Gonçalves, Raquel M.; Barbosa, Mário A.

    2015-01-01

    Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players. PMID:25673296

  15. Fission gas release behaviour of a 103 GWd/tHM fuel disc during a 1200 °C annealing test

    International Nuclear Information System (INIS)

    Noirot, J.; Pontillon, Y.; Yagnik, S.; Turnbull, J.A.; Tverberg, T.

    2014-01-01

    Within the Nuclear Fuel Industry Research (NFIR) program, several fuel variants, in the form of thin circular discs, were irradiated in the Halden Boiling Water Reactor (HBWR) to a range of burn-ups ∼100 GWd/t HM . The design of the assembly was similar to that used in other HBWR programs: the assembly contained several rods with fuel discs sandwiched between Mo discs, which limited temperature gradients within the fuel discs. One such rod contained standard grain UO 2 discs (3D grain size = 18 μm) reaching a burn-up of 103 GWd/t HM . After the irradiation, the gas release upon rod puncturing was measured to be 2.9%. Detailed characterizations of one of these irradiated UO 2 discs, using electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS), were performed in a CEA Cadarache hot laboratory. Examination revealed the high burn-up structure (HBS) formation throughout the whole of the disc, also the fission gas distribution within this HBS, with a very high proportion of the gas in the HBS bubbles. A sibling disc was submitted to a temperature transient up to 1200 °C in the out-of-pile (OOP) annealing test device “Merarg” at a relatively low temperature ramp rate (0.2 °C/s). In addition to the total gas release during this annealing test, the release peaks throughout the temperature range were monitored. The fuel was then characterized with the same microanalysis techniques as before the annealing test to investigate the effects of this test on the microstructure of the fuel and on the fission gases. It provided valuable insights into fission gas localization and the release behaviour in UO 2 fuel with high burn-up structure (HBS)

  16. Influence of degenerative changes of intervertebral disc

    Directory of Open Access Journals (Sweden)

    WANG Yi

    2012-04-01

    Full Text Available 【Abstract】Objective: To investigate the material properties of normal and degenerated intervertebral discs (IVDs and examine the effect of degenerative changes on IVD pathology. Methods: A computer-based online search was under-taken to identify English articles about material properties of IVDs published from January 1950 to 2011 in PubMed database. The retrieved keywords included material properties, intervertebral disc and degeneration. Based on the principles of reliability, advancement and efficiency, the obtained data were primarily examined, and the original source was retrieved to read the full-text. Repetitive articles were excluded. The data of material properties of normal and degenerated IVDs were summarized and analyzed by meta-analysis. Results: The data of Young's modulus, Poisson's ratio, shear modulus, hydraulic permeability and intradiscal pres-sure of normal and degenerated IVDs were obtained. Com-pared with normal IVDs, the Young's modulus and shear modulus of annulus fibrosus and nucleus pulposus were higher in degenerated IVDs, the Poisson's ratio was lower while the hydraulic permeability and intradiscal pressure were higher. Besides, the degeneration-related alterations in IVDs had an influence both on itself and other spinal structures, leading to diseases such as bulging disc, discogenic pain and spinal stenosis. Meanwhile, the heavy mechanical loading and injury indicated important pathways to IVD degeneration. Conclusions: To a certain extent, the degenerative changes of IVD influence its material properties. And the degeneration-related alterations of composition can cause structural failure of IVDs, leading to injuries and diseases. Key words: Intervertebral disc; Mechanical phenomena; Degeneration; Elastic modulus; Permeability; Pathology

  17. [Treatment of thoracic disc herniation. Case report].

    Science.gov (United States)

    Picado-Baca, Mauricio Leonardo; Mireles-Cano, José Nicolás; León-Meza, Víctor Manuel; García-González, Oscar Guillermo; Ramos-Trujillo, Alejandro

    2016-01-01

    Herniated thoracic intervertebral disc is a rare cause of spinal cord compression. Its frequency varies from 0.15% to 1.7% of all disc herniations, and produces symptoms in 0.5% to 0.8%. Case 1. A 50-year-old woman, with pain and burning sensation in left hemithorax of four months of onset. It was treated as a herpetic syndrome, with no improvement. She was seen after thirteen days of exacerbation of clinical symptoms. The physical examination showed asymmetric paraparesis, lower left pelvic limb 1/5, and right pelvic limb 3/5¸ sensory level T8, with left Babinski positive. A thoracic disc herniation in space T8-T9 was diagnosed. A 55-year-old patient with a history of presenting pain in lumbar area of 5 years onset. She also had radicular pain that radiated to the right pelvic limb, with intensity 10/10 on a Visual Analogue Scale. Her physical examination showed muscle strength 5/5, with normal sensitivity in all dermatomes and tendon reflexes, and a positive right Babinski. Thoracic disc herniation T7-T8 level was diagnosed. Due to anatomical conditions that define this type of hernia, the extracavitary posterolateral approach should be the recommended surgical procedure when the simultaneously performed anterior decompression and fixation with posterior instrumentation are the treatments proposed. Despite the different anatomical structures of this special area, it was possible to obtain satisfactory results for both clinical cases. Copyright © 2015 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  18. Development of Vibrating Disc Piezoelectric Gyroscope

    OpenAIRE

    A.K. Singh; U.K. Gorain

    2004-01-01

    The paper presents an indigenously developed vibrating disc piezoelectric gyroscope, in which both excitation and detection have been done through piezoelectric, using PZT-5H material. The gyroscope has been driven to resonant state by direct piezoelectric effect, using 20 V ac signal at 93 kHz, and the output has been detected by the reverse piezoelectric effect.The performance of this gyroscope has been tested with 3 microprocessor-controlled turntable, and the output of the gyroscope has b...

  19. Footprint mismatch in total cervical disc arthroplasty.

    Science.gov (United States)

    Thaler, Martin; Hartmann, Sebastian; Gstöttner, Michaela; Lechner, Ricarda; Gabl, Michael; Bach, Christian

    2013-04-01

    Cervical disc arthroplasty has become a commonplace surgery for the treatment of cervical radiculopathy and myelopathy. Most manufacturers derive their implant dimensions from early published cadaver studies. Ideal footprint match of the prosthesis is essential for good surgical outcome. We measured the dimensions of cervical vertebrae from computed tomography (CT) scans and to assess the accuracy of match achieved with the most common cervical disc prostheses [Bryan (Medtronic), Prestige LP (Medtronic), Discover (DePuy) Prodisc-C (Synthes)]. A total of 192 endplates in 24 patients (56.3 years) were assessed. The anterior-posterior and mediolateral diameters of the superior and inferior endplates were measured with a digital measuring system. Overall, 53.5 % of the largest device footprints were smaller in the anterior-posterior diameter and 51.1 % in the mediolateral diameter were smaller than cervical endplate diameters. For levels C5/C6 and C6/C7 an inappropriate size match was noted in 61.9 % as calculated from the anteroposterior diameter. Mismatch at the center mediolateral diameter was noted in 56.8 %. Of the endplates in the current study up to 58.1 % of C5/C6 and C6/C7, and up to 45.3 % of C3/C4 and C4/C5 were larger than the most frequently implanted cervical disc devices. Surgeons and manufacturers should be aware of the size mismatch in currently available cervical disc prostheses, which may endanger the safety and efficacy of the procedure. Undersizing the prosthetic device may lead to subsidence, loosening, heterotopic ossification and biomechanical failure caused by an incorrect center of rotation and load distribution, affecting the facet joints.

  20. Risk Factors for Recurrent Lumbar Disc Herniation

    Science.gov (United States)

    Huang, Weimin; Han, Zhiwei; Liu, Jiang; Yu, Lili; Yu, Xiuchun

    2016-01-01

    Abstract Recurrent lumbar disc herniation (rLDH) is a common complication following primary discectomy. This systematic review aimed to investigate the current evidence on risk factors for rLDH. Cohort or case-control studies addressing risk factors for rLDH were identified by search in Pubmed (Medline), Embase, Web of Science, and Cochrane library from inception to June 2015. Relevant results were pooled to give overall estimates if possible. Heterogeneity among studies was examined and publication bias was also assessed. A total of 17 studies were included in this systematic review. Risk factors that had significant relation with rLDH were smoking (OR 1.99, 95% CI 1.53–2.58), disc protrusion (OR 1.79, 95% CI 1.15–2.79), and diabetes (OR 1.19, 95% CI 1.06–1.32). Gender, BMI, occupational work, level, and side of herniation did not correlate with rLDH significantly. Based on current evidence, smoking, disc protrusion, and diabetes were predictors for rLDH. Patients with these risk factors should be paid more attention for prevention of recurrence after primary surgery. More evidence provided by high-quality observational studies is still needed to further investigate risk factors for rLDH. PMID:26765413

  1. Chipping machines: disc and drum energy requirements

    Directory of Open Access Journals (Sweden)

    Alessio Facello

    2013-09-01

    Full Text Available Air pollution and fossil fuel reserves exhaustion are increasing the importance of the biomass-derived products, in particular wood, as source of clean and renewable energy for the production of electricity or steam. In order to improve the global efficiency and the entire production chain, we have to evaluate the energetic aspects linked to the process of transformation, handling and transport of these materials. This paper reports results on a comparison between two chippers of similar size using different cutting technology: disc and drum tool respectively. During trials, fuel consumption, PTO torque and speed, processing time and weight of processed material were recorded. Power demand, fuel consumption, specific energy and productivity were computed. The machine was fed with four different feedstock types (chestnut logs, poplar logs, poplar branches, poplar sawmill residues. 15 repetitions for each combination of feedstock-tool were carried out. The results of this study show that the disc tool requires, depending on the processed material, from 12 to 18% less fuel per unit of material processed than the drum tool, and consequently, from 12 to 16% less specific energy. In particular, the highest difference between tools was found in branches processing whereas the smallest was in poplar logs. Furthermore the results of the investigation indicate, that, in testing conditions, the productivity of drum tool is higher (8% than disc tool.

  2. Hypokalemia mimicking a herniated vertebral disc.

    Science.gov (United States)

    Delhey, Patrick Roman; Holzapfel, Boris Michael; Kanz, Karl-Georg; Mayer-Wagner, Susanne

    2015-06-01

    A herniated vertebral disc is a common cause of paralysis. Other causes include infections, tumors, and neurologic diseases. A rare and dangerous but in most cases easily treatable cause is hypokalemia. Clinically, the acute symptoms may resemble a herniated vertebral disc, but hypokalemia per se is life-threatening by causing heart arrest through ventricular tachycardia or fibrillation. A patient with back pain and neurologic deficit in the lower extremities after a history of a herniated vertebral disc presented, who finally receives the diagnosis of hypokalemia. Case report. A 25-year-old female patient presenting after a fall with muscle weakness in both legs was followed clinically and radiographically. Neurological examination showed a lower extremity muscle weakness with three-fifths muscular strength of the quadriceps and tibialis anterior muscle on both sides. Reflexes were diminished bilaterally, anal sphincter tone was normal. Plain radiography suggested a posterior rim fracture of L5, but computed tomography did not confirm this diagnosis. The laboratory investigation revealed a hypokalemia of 1.7 mEq/L. On electrolyte replacement, the patient recovered immediately. This report describes a misleading diagnostic case of back pain and neurologic deficit after a trauma and sensitizes for the possible life-threatening diagnosis hypokalemia, which is rare but easily treatable. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Human umbilical cord derivatives regenerate intervertebral disc.

    Science.gov (United States)

    Beeravolu, Naimisha; Brougham, Jared; Khan, Irfan; McKee, Christina; Perez-Cruet, Mick; Chaudhry, G Rasul

    2016-09-30

    Intervertebral disc (IVD) degeneration is characterized by the loss of nucleus pulposus (NP), which is a common cause for lower back pain. Although, currently, there is no cure for the degenerative disc disease, stem cell therapy is increasingly being considered for its treatment. In this study, we investigated the feasibility and efficacy of human umbilical cord mesenchymal stem cells (MSCs) and chondroprogenitor cells (CPCs) derived from those cells to regenerate damaged IVD in a rabbit model. Transplanted cells survived, engrafted and dispersed into NP in situ. Significant improvement in the histology, cellularity, extracellular matrix proteins, and water and glycosaminoglycan contents in IVD recipients of CPCs was observed compared to MSCs. In addition, IVDs receiving CPCs exhibited higher expression of NP-specific human markers, SOX9, aggrecan, collagen 2, FOXF1 and KRT19. The novelty of the study is that in vitro differentiated CPCs derived from umbilical cord MSCs, demonstrated far greater capacity to regenerate damaged IVDs, which provides basis and impetus for stem cell based clinical studies to treat degenerative disc disease. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Dynamic analysis of three autoventilated disc brakes

    Directory of Open Access Journals (Sweden)

    Ricardo A. García-León

    2017-09-01

    Full Text Available The braking system of a car must meet several requirements, among which safety is the most important. It is also composed of a set of mechanical parts such as springs, different types of materials (Metallic and Non Metallic, gases and liquids. The brakes must work safely and predictably in all circumstances, which means having a stable level of friction, in any condition of temperature, humidity and salinity of the environment. For a correct design and operation of brake discs, it is necessary to consider different aspects, such as geometry, type of material, mechanical strength, maximum temperature, thermal deformation, cracking resistance, among others. Therefore, the main objective of this work is to analyze the dynamics and kinetics of the brake system from the pedal as the beginning of mathematical calculations to simulate the behavior and Analysis of Finite Elements (FEA, with the help of SolidWorks Simulation Software. The results show that the third brake disc works best in relation to the other two discs in their different working conditions such as speed and displacement in braking, concluding that depending on the geometry of the brake and the cooling channels these systems can be optimized that are of great importance for the automotive industry.

  5. Total disc replacement using tissue-engineered intervertebral discs in the canine cervical spine.

    Directory of Open Access Journals (Sweden)

    Yu Moriguchi

    Full Text Available The most common reason that adults in the United States see their physician is lower back or neck pain secondary to degenerative disc disease. To date, approaches to treat degenerative disc disease are confined to purely mechanical devices designed to either eliminate or enable flexibility of the diseased motion segment. Tissue engineered intervertebral discs (TE-IVDs have been proposed as an alternative approach and have shown promise in replacing native IVD in the rodent tail spine. Here we demonstrate the efficacy of our TE-IVDs in the canine cervical spine. TE-IVD components were constructed using adult canine annulus fibrosis and nucleus pulposus cells seeded into collagen and alginate hydrogels, respectively. Seeded gels were formed into a single disc unit using molds designed from the geometry of the canine spine. Skeletally mature beagles underwent discectomy with whole IVD resection at levels between C3/4 and C6/7, and were then divided into two groups that received only discectomy or discectomy followed by implantation of TE-IVD. Stably implanted TE-IVDs demonstrated significant retention of disc height and physiological hydration compared to discectomy control. Both 4-week and 16-week histological assessments demonstrated chondrocytic cells surrounded by proteoglycan-rich matrices in the NP and by fibrocartilaginous matrices in the AF portions of implanted TE-IVDs. Integration into host tissue was confirmed over 16 weeks without any signs of immune reaction. Despite the significant biomechanical demands of the beagle cervical spine, our stably implanted TE-IVDs maintained their position, structure and hydration as well as disc height over 16 weeks in vivo.

  6. The life cycles of Be viscous decretion discs: fundamental disc parameters of 54 SMC Be stars

    Science.gov (United States)

    Rímulo, L. R.; Carciofi, A. C.; Vieira, R. G.; Rivinius, Th; Faes, D. M.; Figueiredo, A. L.; Bjorkman, J. E.; Georgy, C.; Ghoreyshi, M. R.; Soszyński, I.

    2018-02-01

    Be stars are main-sequence massive stars with emission features in their spectrum, which originates in circumstellar gaseous discs. Even though the viscous decretion disc (VDD) model can satisfactorily explain most observations, two important physical ingredients, namely the magnitude of the viscosity (α) and the disk mass injection rate, remain poorly constrained. The light curves of Be stars that undergo events of disc formation and dissipation offer an opportunity to constrain these quantities. A pipeline was developed to model these events that uses a grid of synthetic light curves, computed from coupled hydrodynamic and radiative transfer calculations. A sample of 54 Be stars from the OGLE survey of the Small Magellanic Cloud (SMC) was selected for this study. Because of the way our sample was selected (bright stars with clear disc events), it likely represents the densest discs in the SMC. Like their siblings in the Galaxy, the mass of the disc in the SMC increases with the stellar mass. The typical mass and angular momentum loss rates associated with the disk events are of the order of ˜10-10 M⊙ yr-1 and ˜5 × 1036 g cm2 s-2, respectively. The values of α found in this work are typically of a few tenths, consistent with recent results in the literature and with the ones found in dwarf novae, but larger than current theory predicts. Considering the sample as a whole, the viscosity parameter is roughly two times larger at build-up (⟨αbu⟩ = 0.63) than at dissipation (⟨αd⟩ = 0.26). Further work is necessary to verify whether this trend is real or a result of some of the model assumptions.

  7. Suspected herniated lumbar disc - computed tomography in differential diagnosis of non-disc-related sciatica

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, T.; Koehler, D.; Treisch, J.; Claussen, C.; Felix, R.

    1984-07-01

    The most common reason a patient is referred for spinal CT examination is to exclude a ruptured intervertebral disc. Besides nerve root entrapment due to herniated disc, a number of unusual or unexpected conditions have been encountered in the course of CT lumbar spine studies. These include spondylolisthesis, spinal dysraphism, Paget's disease, and inflammatory, neoplastic, or metastatic lesions. The application of spinal (small-circle) target imaging includes the risk of overlooking soft tissue lesions that extend beyond the reconstruction circle. Therefore, complete (large-circle) circumferential abdominal scanning is recommended in case of a suspected extraspinal cause of sciatica.

  8. A method for quantitative measurement of lumbar intervertebral disc structures

    DEFF Research Database (Denmark)

    Tunset, Andreas; Kjær, Per; Samir Chreiteh, Shadi

    2013-01-01

    There is a shortage of agreement studies relevant for measuring changes over time in lumbar intervertebral disc structures. The objectives of this study were: 1) to develop a method for measurement of intervertebral disc height, anterior and posterior disc material and dural sac diameter using MRI......, 2) to evaluate intra- and inter-rater agreement and reliability for the measurements included, and 3) to identify factors compromising agreement....

  9. Thoracic spine disc-related abnormalities: longitudinal MR imaging assessment

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Charles J.; Schweitzer, Mark E.; Morrison, William B.; Parellada, Joan A. [TJUH Radiology, Philadelphia, Pennsylvania (United States); Carrino, J.A. [Department of Radiology ASB-1, Harvard Medical School, Brigham and Women' s Hospital, L1, Room 002B, 75 Francis Street, MA 02115, Boston (United States)

    2004-04-01

    To describe and characterize the temporal changes in disc-related disorders of the thoracic spine using MR imaging. A retrospective longitudinal cohort study was carried out of 40 patients with two sequential thoracic spine MR images at variable intervals. The images were assessed for baseline presence of, new incidence of and changes in disc herniation, degenerative disc disease, endplate marrow signal alteration and Schmorl nodes. The range of follow-up was 4-149 weeks. Baseline presence was: disc herniation, 10% (49/480); degenerative disc disease, 14% (66/480); endplate marrow signal alteration, 2.3% (11/480); Schmorl nodes 9.6% (46/480). Most pre-existing lesions tended to remain unchanged. Herniations showed the most change, tending to improve in 27%. New incidence was: disc herniation, 1.5% (7/480), degenerative disc disease, 2% (10/480); endplate marrow signal alteration, 1.6% (8/480); Schmorl nodes, 2.1% (10/480). Disc degeneration was first visible at an 11-week interval and once established almost never changed over many weeks to months. Endplate signal alterations (Modic changes) were uncommon. Schmorl nodes show no change from baseline for up to 2 1/2 years. All findings predominated in the lower intervertebral levels from T6 to T10. The most prevalent thoracic spine disc-related findings are degeneration and herniation. Disc herniations predominate in the lower segments and are a dynamic phenomenon. Disc degeneration can be rapidly evolving but tends to remain unchanged after occurrence. Endplate marrow signal changes were an uncommon manifestation of thoracic disc disease. Schmorl nodes showed the least change over time. (orig.)

  10. Spontaneous resolution of a herniated fragment cervical disc

    OpenAIRE

    METE, Mesut; SAVRAN, Mehmet; DEMİRÇİVİ ÖZER, Füsun; DURANSOY, Yusuf Kurtuluş

    2012-01-01

    ABSTRACT Although the spontaneous resolution of herniated nucleus pulposus is a well known phe¬nomenon in lumbar disc herniations, it is rarely encountered in the cervical region. The spontaneous resolution of a herniated cervical disc in a woman is reported to describe a rare occurrence of spontaneous regression of a cervical herniated nucleus pulposus and to discuss its mechanism. A woman with a large and fragment herniated cervical disc refused to undergo operation and was followed-up ...

  11. Glaucomatous-Type Optic Discs in High Myopia.

    Directory of Open Access Journals (Sweden)

    Natsuko Nagaoka

    Full Text Available To assess the prevalence of glaucoma in patients with high myopia defined as myopic refractive error of >-8 diopters or axial length ≥26.5 mm.The hospital-based observational study included 172 patients (336 eyes with a mean age of 61.9±12.3 years and mean axial length of 30.1±2.3 mm (range: 24.7-39.1mm. Glaucomatous-type optic discs were defined by glaucomatous optic disc appearance. Glaucoma was defined by glaucomatous optic disc appearance and glaucomatous Goldmann visual field defects not corresponding with myopic macular changes.Larger disc area (mean: 3.18±1.94 mm2 was associated with longer axial length (P3.79 mm2 than in normal-sized discs or small discs (<1.51 mm2 after adjusting for older age. Axial length was not significantly (P = 0.38 associated with glaucoma prevalence in that model. Glaucoma prevalence increased by a factor of 1.39 for each increase in optic disc area by one mm2. Again, axial length was not significantly (P = 0.38 associated with glaucoma prevalence when added to this multivariate model.Within highly myopic individuals, glaucoma prevalence increased with larger optic disc size beyond a disc area of 3.8 mm2. Highly myopic megalodiscs as compared to normal sized discs or small discs had a 3.2 times higher risk for glaucomatous optic nerve neuropathy. The increased glaucoma prevalence in axial high myopia was primarily associated with axial myopia associated disc enlargement and not with axial elongation itself.

  12. New Brown Dwarf Discs in Upper Scorpius Observed with WISE

    Science.gov (United States)

    Dawson, P.; Scholz, A.; Ray, T. P.; Natta, A.; Marsh, K. A.; Padgett, D.; Ressler, M. E.

    2013-01-01

    We present a census of the disc population for UKIDSS selected brown dwarfs in the 5-10 Myr old Upper Scorpius OB association. For 116 objects originally identified in UKIDSS, the majority of them not studied in previous publications, we obtain photometry from the Wide-Field Infrared Survey Explorer data base. The resulting colour magnitude and colour colour plots clearly show two separate populations of objects, interpreted as brown dwarfs with discs (class II) and without discs (class III). We identify 27 class II brown dwarfs, 14 of them not previously known. This disc fraction (27 out of 116, or 23%) among brown dwarfs was found to be similar to results for K/M stars in Upper Scorpius, suggesting that the lifetimes of discs are independent of the mass of the central object for low-mass stars and brown dwarfs. 5 out of 27 discs (19 per cent) lack excess at 3.4 and 4.6 microns and are potential transition discs (i.e. are in transition from class II to class III). The transition disc fraction is comparable to low-mass stars.We estimate that the time-scale for a typical transition from class II to class III is less than 0.4 Myr for brown dwarfs. These results suggest that the evolution of brown dwarf discs mirrors the behaviour of discs around low-mass stars, with disc lifetimes of the order of 5 10 Myr and a disc clearing time-scale significantly shorter than 1 Myr.

  13. Magnetic Resonance Imaging in the Diagnostics of Spinal Disc Herniations

    OpenAIRE

    Katsiaryna, A.; Dmitry, A.

    2015-01-01

    BACKGROUND Currently the preoperative detection of degenerative disc diseases does not always correlate with neurological symptoms and present status of a patient. This paper outlines the possibilities of using magnetic resonance imaging in evaluation of thethe grade of severity of intervertebral disc herniations. METHODS A total 20 patients of the disc herniations with age group between 20 to 81 y were diagnosed and studied on «Avanta» highfield Magnetic Resonance Imaging machine by «Siemens...

  14. Spontaneous Regression of Intervertebral Disc Herniation – Case Reports

    OpenAIRE

    Rapan, Saša; Gulan, Gordan; Lovrić, Ivan; Jovanović, Savo

    2011-01-01

    Lumbar disc hernia (LDH) is a common cause of low back pain and radicular leg pain. It is well known that the majority of LDH patients recover spontaneously. Since the advent of MRI, a spontaneous regression of fragment size of disc hernia occurs, as well as mitigation of subjective difficulties and neurological disorders. Therefore, surgical treatment is not always method of choice in this disease. Two cases of conservatively treated large disc extrusion which result in significant ...

  15. Fenomena Komunikasi Female Disc Jockey di Kota Pekanbaru

    OpenAIRE

    Febriasistari, Atika Hersa; Wirman, Welly

    2016-01-01

    Female Disc Jockey becomes a phenomenon that thriving nowadays. Female Disc Jockey comes from different circle such student and even housewife. Until now the phenomenon of Female Disc Jockey is getting more develop marked by increasing the number of their performance on many event such night club in Pekanbaru. On their performance they often wearing sexy clothes. Meanwhile their work place is close to some kind of negative such alcohol, drugs, freesex and led to a negative stigma from many pe...

  16. ANALYSIS OF OPTIC DISC AND PERIPAPILLARY AREA USING OPTICAL COHERENCE TOMOGRAPHY IN YOUNG ADULT INDIAN MYOPIC EYES AT AMBEDKAR MEDICAL COLLEGE

    Directory of Open Access Journals (Sweden)

    Rani

    2016-03-01

    caution before labelling them as glaucomatous or any other disease causing RNFL thinning and variation in ONH values. Clinical correlation along with OCT parameters are essential before formulating a definitive diagnosis. CONCLUSION OCT is a non-contact, non-invasive imaging modality that is used to take high resolution, in-vivo, and cross-sectional pictures of the optic nerve head. OCT, thus, helps to quantify the structural damage that an eye has suffered due to glaucoma. While performing OCT studies in normal (emmetrope and myopic eyes in the current investigation, it was found that there was thinning in the retinal nerve fibre layer in superior, inferior, nasal and average thickness values in myopic eyes which was more marked in moderate to high myopia than in mild myopia. The disc area was smaller in high myopes compared to the normal eyes. The cup volume was smaller in high myopes which correlated with the smaller disc area. There was no significant correlation between spherical equivalent and RNFLT. Myopic patients review periodically for their refractive error correction. Myopic disc findings may mimic optic disc changes suggestive of optic neuropathy. The data obtained in the current investigation suggests that optic disc parameters vary in myopic eyes compared to emmetropic eyes by spectral domain OCT. therefore, in myopic eyes, OCT parameters should be interpreted with caution before labelling them as glaucomatous or any other disease causing RNFL thinning and variation in ONH values. Clinical correlation along with OCT parameters are essential before formulating a definitive diagnosis.

  17. Apparent quasar disc sizes in the "bird's nest" paradigm

    Science.gov (United States)

    Abolmasov, P.

    2017-04-01

    Context. Quasar microlensing effects make it possible to measure the accretion disc sizes around distant supermassive black holes that are still well beyond the spatial resolution of contemporary instrumentation. The sizes measured with this technique appear inconsistent with the standard accretion disc model. Not only are the measured accretion disc sizes larger, but their dependence on wavelength is in most cases completely different from the predictions of the standard model. Aims: We suggest that these discrepancies may arise not from non-standard accretion disc structure or systematic errors, as it was proposed before, but rather from scattering and reprocession of the radiation of the disc. In particular, the matter falling from the gaseous torus and presumably feeding the accretion disc may at certain distances become ionized and produce an extended halo that is free from colour gradients. Methods: A simple analytical model is proposed assuming that a geometrically thick translucent inflow acts as a scattering mirror changing the apparent spatial properties of the disc. This inflow may be also identified with the broad line region or its inner parts. Results: Such a model is able to explain the basic properties of the apparent disc sizes, primarily their large values and their shallow dependence on wavelength. The only condition required is to scatter a significant portion of the luminosity of the disc. This can easily be fulfilled if the scattering inflow has a large geometrical thickness and clumpy structure.

  18. Surface image of herniated disc on three-dimensional CT

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyung Il; Jeon, Chang Hoon; Kim, Sun Yong; Kim, Ok Hwa; Suh, Jung Ho [Ajou Univ. College of Medicine, Suwon(Korea, Republic of)

    1996-03-01

    To evaluate surface configuration of herniated disc on three-dimensional CT. Three dimensional surface images reconstructed from CT scans(1 mm thick) of 24 surgically confirmed herniated discs in 23 patients were reviewed. Disc surface was classified into peripheral and central zones in contact with consecutive peripheral ring and central endplate. Surface irregularity was categorized into two types(local and general). The incidence, size, and extent of local irregularity were observed. General irregularity incidence and severity ranges in 4 grades, and peripheral width were evaluated. The findings were correlated with discography. Local irregularity compatible with anulus tear in discography was shown in all. It was large(13/24) and mainly peripheral tract extending to disc margin in protrusion(3/5) and sequestration(5/7), and cleft encompassing central zone to disc margin in extrusion(9/12). General irregularity was predominantly grade 3(15/22) and was shown in all except in 2 protrusions. Peripheral width was 0.56 of central radius. Extrusion in herniated disc shows characteristic cleft encompassing central zone to disc margin whereas sequestration or protrusion displays tract extending from peripheral zone to disc margin. Thus, three dimensional surface imaging may aid the diagnosis, follow-up, prediction, and treatment of herniated disc.

  19. Acupuncture and Spontaneous Regression of a Radiculopathic Cervical Herniated Disc

    Directory of Open Access Journals (Sweden)

    Kim Sung-Ha

    2012-06-01

    Full Text Available The spontaneous regression of herniated cervical discs is not a well-established phenomenon. However, we encountered a case of a spontaneous regression of a severe radiculopathic herniated cervical disc that was treated with acupuncture, pharmacopuncture, and herb medicine. The symptoms were improved within 12 months of treatment. Magnetic resonance imaging (MRI conducted at that time revealed marked regression of the herniated disc. This case provides an additional example of spontaneous regression of a herniated cervical disc documented by MRI following non-surgical treatment.

  20. Gene expression profile analysis of human intervertebral disc degeneration

    Directory of Open Access Journals (Sweden)

    Kai Chen

    2013-01-01

    Full Text Available In this study, we used microarray analysis to investigate the biogenesis and progression of intervertebral disc degeneration. The gene expression profiles of 37 disc tissue samples obtained from patients with herniated discs and degenerative disc disease collected by the National Cancer Institute Cooperative Tissue Network were analyzed. Differentially expressed genes between more and less degenerated discs were identified by significant analysis of microarray. A total of 555 genes were significantly overexpressed in more degenerated discs with a false discovery rate of < 3%. Functional annotation showed that these genes were significantly associated with membrane-bound vesicles, calcium ion binding and extracellular matrix. Protein-protein interaction analysis showed that these genes, including previously reported genes such as fibronectin, COL2A1 and f-catenin, may play key roles in disc degeneration. Unsupervised clustering indicated that the widely used morphology-based Thompson grading system was only marginally associated with the molecular classification of intervertebral disc degeneration. These findings indicate that detailed, systematic gene analysis may be a useful way of studying the biology of intervertebral disc degeneration.

  1. Acupuncture and spontaneous regression of a radiculopathic cervical herniated disc.

    Science.gov (United States)

    Kim, Sung-Ha; Park, Man-Young; Lee, Sang-Mi; Jung, Ho-Hyun; Kim, Jae-Kyoun; Lee, Jong-Deok; Kim, Dong-Woung; Yeom, Seung-Ryong; Lim, Jin-Young; Park, Min-Jung; Park, Se-Woon; Kim, Sung-Chul

    2012-06-01

    The spontaneous regression of herniated cervical discs is not a well-established phenomenon. However, we encountered a case of a spontaneous regression of a severe radiculopathic herniated cervical disc that was treated with acupuncture, pharmacopuncture, and herb medicine. The symptoms were improved within 12 months of treatment. Magnetic resonance imaging (MRI) conducted at that time revealed marked regression of the herniated disc. This case provides an additional example of spontaneous regression of a herniated cervical disc documented by MRI following non-surgical treatment.

  2. Spontaneous regression of a lumbar disc herniation: case report

    Directory of Open Access Journals (Sweden)

    Mostarchid Brahim El

    2016-12-01

    Full Text Available Lumbar disc herniation is a common disease that induces back pain and radicular pain. Some cases require conservative treatment or at times relived spontaneously. Spontaneous regression of disc herniation is an atypical clinical presentation, and it has been recognized with the advancement of recent advances in imaging techniques. We present a 35-year-old woman presented a spontaneous regression of a lumbar disc herniation with good outcome after intensive physical therapy program. Spontaneous regression of disc herniation is thought to occur via an inflammatory reaction with molecular mechanisms of phagocytic processes.

  3. Power diagrams and interaction processes for unions of discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisova, Katarina

    We study a flexible class of finite disc process models with interaction between the discs. We let U denote the random set given by the union of discs, and use for the disc process an exponential family density with the canonical sufficient statistic only depending on geometric properties of U......, becomes useful for handling the problem of edge effects when only U is observed within a bounded observation window. The power tessellation and its dual graph become major tools when establishing inclusion-exclusion formulae, formulae for computing geometric characteristics of U, and stability properties...

  4. Power diagrams and interaction processes for unions of discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisova, Katerina

    2008-01-01

     We study a flexible class of finite-disc process models with interaction between the discs. We let U denote the random set given by the union of discs, and use for the disc process an exponential family density with the canonical sufficient statistic depending only on geometric properties of U......, becomes useful for handling the problem of edge effects when only U is observed within a bounded observation window. The power tessellation and its dual graph become major tools when establishing inclusion-exclusion formulae, formulae for computing geometric characteristics of U, and stability properties...

  5. Metallicity gradient of the thick disc progenitor at high redshift

    Science.gov (United States)

    Kawata, Daisuke; Allende Prieto, Carlos; Brook, Chris B.; Casagrande, Luca; Ciucă, Ioana; Gibson, Brad K.; Grand, Robert J. J.; Hayden, Michael R.; Hunt, Jason A. S.

    2018-01-01

    We have developed a novel Markov Chain Monte Carlo chemical 'painting' technique to explore possible radial and vertical metallicity gradients for the thick disc progenitor. In our analysis, we match an N-body simulation to the data from the Apache Point Observatory Galactic Evolution Experiment survey. We assume that the thick disc has a constant scaleheight and has completed its formation at an early epoch, after which time radial mixing of its stars has taken place. Under these assumptions, we find that the initial radial metallicity gradient of the thick disc progenitor should not be negative, but either flat or even positive, to explain the current negative vertical metallicity gradient of the thick disc. Our study suggests that the thick disc was built-up in an inside-out and upside-down fashion, and older, smaller and thicker populations are more metal poor. In this case, star-forming discs at different epochs of the thick disc formation are allowed to have different radial metallicity gradients, including a negative one, which helps to explain a variety of slopes observed in high-redshift disc galaxies. This scenario helps to explain the positive slope of the metallicity-rotation velocity relation observed for the Galactic thick disc. On the other hand, radial mixing flattens the slope of an existing gradient.

  6. Spiral-driven accretion in protoplanetary discs . III. Tridimensional simulations

    Science.gov (United States)

    Hennebelle, Patrick; Lesur, Geoffroy; Fromang, Sébastien

    2017-03-01

    Context. Understanding how accretion proceeds in proto-planetary discs, and more generally, understanding their dynamics, is a crucial questions that needs to be answered to explain the conditions in which planets form. Aims: The role that accretion of gas from the surrounding molecular cloud onto the disc may have on its structure needs to be quantified. Methods: We performed tridimensional simulations using the Cartesian AMR code RAMSES of an accretion disc that is subject to infalling material. Results: For the aspect ratio of H/R ≃ 0.15 and disc mass Md ≃ 10-2M⊙ used in our study, we find that for typical accretion rates of the order of a few 10-7M⊙ yr-1, values of the α parameter as high as a few 10-3 are inferred. The mass that is accreted in the inner part of the disc is typically at least 50% of the total mass that has been accreted onto the disc. Conclusions: Our results suggest that external accretion of gas at moderate values onto circumstellar discs may trigger prominent spiral arms that are reminiscent of recent observations made with various instruments, and may lead to significant transport through the disc. If confirmed from observational studies, such accretion may therefore influence disc evolution.

  7. Notochord Cells in Intervertebral Disc Development and Degeneration

    Directory of Open Access Journals (Sweden)

    Matthew R. McCann

    2016-01-01

    Full Text Available The intervertebral disc is a complex structure responsible for flexibility, multi-axial motion, and load transmission throughout the spine. Importantly, degeneration of the intervertebral disc is thought to be an initiating factor for back pain. Due to a lack of understanding of the pathways that govern disc degeneration, there are currently no disease-modifying treatments to delay or prevent degenerative disc disease. This review presents an overview of our current understanding of the developmental processes that regulate intervertebral disc formation, with particular emphasis on the role of the notochord and notochord-derived cells in disc homeostasis and how their loss can result in degeneration. We then describe the role of small animal models in understanding the development of the disc and their use to interrogate disc degeneration and associated pathologies. Finally, we highlight essential development pathways that are associated with disc degeneration and/or implicated in the reparative response of the tissue that might serve as targets for future therapeutic approaches.

  8. New directions in the treatment of degenerative disc disease

    Directory of Open Access Journals (Sweden)

    Robert Gasik

    2014-11-01

    Full Text Available Degenerative lesions in intervertebral discs rank among the most common causes of spinal pain syndromes. Conservative treatment, pharmacotherapy and rehabilitation focus on the elimination of pain symptoms without addressing the underlying cause of the pain. Surgical techniques applied to date have, in turn, eliminated the cause of the pain while failing to halt the degeneration process affecting the discs. The future of the treatment of degenerative disc lesions lies in methods affecting the nutrition, improving the hydration and stimulating the regeneration of intervertebral discs, as outlined in the present study.

  9. Bovine explant model of degeneration of the intervertebral disc

    Directory of Open Access Journals (Sweden)

    Sivan Sarit

    2008-02-01

    Full Text Available Abstract Background Many new treatments for degeneration of the intervertebral disc are being developed which can be delivered through a needle. These require testing in model systems before being used in human patients. Unfortunately, because of differences in anatomy, there are no ideal animal models of disc degeneration. Bovine explant model systems have many advantages but it is not possible to inject any significant volume into an intact disc. Therefore we have attempted to mimic disc degeneration in an explant bovine model via enzymatic digestion. Methods Bovine coccygeal discs were incubated with different concentrations of the proteolytic enzymes, trypsin and papain, and maintained in culture for up to 3 weeks. A radio-opaque solution was injected to visualise cavities generated. Degenerative features were monitored histologically and biochemically (water and glycosaminoglycan content, via dimethylmethylene blue. Results and Conclusion The central region of both papain and trypsin treated discs was macro- and microscopically fragmented, with severe loss of metachromasia. The integrity of the surrounding tissue was mostly in tact with cells in the outer annulus appearing viable. Biochemical analysis demonstrated greatly reduced glycosaminoglycan content in these compared to untreated discs. We have shown that bovine coccygeal discs, treated with proteolytic enzymes can provide a useful in vitro model system for developing and testing potential new treatments of disc degeneration, such as injectable implants or biological therapies.

  10. Disc electrophoresis and related techniques of polyacrylamide gel electrophoresis

    National Research Council Canada - National Science Library

    Maurer, H. R

    1971-01-01

    ..., enzymes, antingens and radioactively labelled materials, and detailed treatments of micro disc electrophoresis, preparative polyacrylamide gel electrophoresis and many other techniques for special problems...

  11. Keplerian planetary orbits in multidimensional Euclidian spaces ...

    African Journals Online (AJOL)

    Newton's laws of motion are three physical laws that together, laid the foundation for classical three dimensional mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to those forces. Kepler's laws of planetary motion are also three scientific laws describing the ...

  12. Explosive magnetorotational instability in Keplerian disks

    Energy Technology Data Exchange (ETDEWEB)

    Shtemler, Yu., E-mail: shtemler@bgu.ac.il; Liverts, E., E-mail: eliverts@bgu.ac.il; Mond, M., E-mail: mond@bgu.ac.il [Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2016-06-15

    Differentially rotating disks under the effect of axial magnetic field are prone to a nonlinear explosive magnetorotational instability (EMRI). The dynamic equations that govern the temporal evolution of the amplitudes of three weakly detuned resonantly interacting modes are derived. As distinct from exponential growth in the strict resonance triads, EMRI occurs due to the resonant interactions of an MRI mode with stable Alfvén–Coriolis and magnetosonic modes. Numerical solutions of the dynamic equations for amplitudes of a triad indicate that two types of perturbations behavior can be excited for resonance conditions: (i) EMRI which leads to infinite values of the three amplitudes within a finite time, and (ii) bounded irregular oscillations of all three amplitudes. Asymptotic explicit solutions of the dynamic equations are obtained for EMRI regimes and are shown to match the numerical solutions near the explosion time.

  13. Time-resolved imaging of a compressible air disc under a drop impacting on a solid surface

    KAUST Repository

    Li, Erqiang

    2015-09-07

    When a drop impacts on a solid surface, its rapid deceleration is cushioned by a thin layer of air, which leads to the entrapment of a bubble under its centre. For large impact velocities the lubrication pressure in this air layer becomes large enough to compress the air. Herein we use high-speed interferometry, with 200 ns time-resolution, to directly observe the thickness evolution of the air layer during the entire bubble entrapment process. The initial disc radius and thickness shows excellent agreement with available theoretical models, based on adiabatic compression. For the largest impact velocities the air is compressed by as much as a factor of 14. Immediately following the contact, the air disc shows rapid vertical expansion. The radial speed of the surface minima just before contact, can reach 50 times the impact velocity of the drop.

  14. Percutaneous thoracic intervertebral disc nucleoplasty: technical notes from 3 patients with painful thoracic disc herniations

    NARCIS (Netherlands)

    Chua Hai Liang, N.; Gultuna, I.; Riezebos, P.; Beems, T.; Vissers, K.C.P.

    2011-01-01

    Symptomatic thoracic disc herniation is an uncommon condition and early surgical approaches were associated with significant morbidity and even mortality. We are the first to describe the technique of percutaneous thoracic nucleoplasty in three patients with severe radicular pain due to thoracic

  15. Analysis of crucial molecules involved in herniated discs and degenerative disc disease

    Directory of Open Access Journals (Sweden)

    Zhigang Qu

    2013-01-01

    Full Text Available OBJECTIVES: Herniated discs and degenerative disc disease are major health problems worldwide. However, their pathogenesis remains obscure. This study aimed to explore the molecular mechanisms of these ailments and to identify underlying therapeutic targets. MATERIAL AND METHODS: Using the GSE23130 microarray datasets downloaded from the Gene Expression Omnibus database, differentially co-expressed genes and links were identified using the differentially co-expressed gene and link method with a false discovery rate ,0.25 as a significant threshold. Subsequently, the underlying molecular mechanisms of the differential co-expression of these genes were investigated using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. In addition, the transcriptional regulatory relationship was also investigated. RESULTS: Through the analysis of the gene expression profiles of different specimens from patients with these diseases, 539 differentially co-expressed genes were identified for these ailments. The ten most significant signaling pathways involving the differentially co-expressed genes were identified by enrichment analysis. Among these pathways, apoptosis and extracellular matrix-receptor interaction pathways have been reported to be related to these diseases. A total of 62 pairs of regulatory relationships between transcription factors and their target genes were identified as critical for the pathogenesis of these diseases. CONCLUSION: The results of our study will help to identify the mechanisms responsible for herniated discs and degenerative disc disease and provides a theoretical basis for further therapeutic study.

  16. Analysis of crucial molecules involved in herniated discs and degenerative disc disease.

    Science.gov (United States)

    Qu, Zhigang; Miao, Weiwei; Zhang, Qi; Wang, Zhenyu; Fu, Changfeng; Han, Jinhua; Liu, Yi

    2013-01-01

    Herniated discs and degenerative disc disease are major health problems worldwide. However, their pathogenesis remains obscure. This study aimed to explore the molecular mechanisms of these ailments and to identify underlying therapeutic targets. Using the GSE23130 microarray datasets downloaded from the Gene Expression Omnibus database, differentially co-expressed genes and links were identified using the differentially co-expressed gene and link method with a false discovery rate ,0.25 as a significant threshold. Subsequently, the underlying molecular mechanisms of the differential co-expression of these genes were investigated using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. In addition, the transcriptional regulatory relationship was also investigated. Through the analysis of the gene expression profiles of different specimens from patients with these diseases, 539 differentially co-expressed genes were identified for these ailments. The ten most significant signaling pathways involving the differentially co-expressed genes were identified by enrichment analysis. Among these pathways, apoptosis and extracellular matrix-receptor interaction pathways have been reported to be related to these diseases. A total of 62 pairs of regulatory relationships between transcription factors and their target genes were identified as critical for the pathogenesis of these diseases. The results of our study will help to identify the mechanisms responsible for herniated discs and degenerative disc disease and provides a theoretical basis for further therapeutic study.

  17. Beyond the standard model of the disc-line spectral profiles from black hole accretion discs

    Czech Academy of Sciences Publication Activity Database

    Sochora, Vjačeslav; Karas, Vladimír; Svoboda, Jiří; Dovčiak, Michal

    2014-01-01

    Roč. 54, č. 4 (2014), s. 301-304 ISSN 1210-2709 R&D Projects: GA ČR(CZ) GC13-00070J Institutional support: RVO:67985815 Keywords : accretion discs * black hole physics * galactic nuclei Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  18. Inner disc obscuration in GRS 1915+105 based on relativistic slim disc model

    Czech Academy of Sciences Publication Activity Database

    Vierdayanti, K.; Sądowski, A.; Mineshige, L.S.; Bursa, Michal

    2013-01-01

    Roč. 436, č. 1 (2013), s. 71-81 ISSN 0035-8711 Institutional support: RVO:67985815 Keywords : accretion discs * black hole physics * GRS 1915+105 Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.226, year: 2013

  19. Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s)

    DEFF Research Database (Denmark)

    Silva Aguirre, V.; Bojsen-Hansen, M.; Slumstrup, D.

    2018-01-01

    Investigations of the origin and evolution of the Milky Way disc have long relied on chemical and kinematic identifications of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted most studies to small samples, normally confined...

  20. Percutaneous treatment of lumbar disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Leonardi, M.; Resta, F.; Bettinelli, A. [Ospedale Maggiore di Milano (Italy); Lavaroni, A.; Fabris, G. [Ospedale Civile di Udine (Italy); Abelli, F. [Fondazione Clinica del Lavorno, Pavia (Italy)

    1994-12-31

    918 patients were subjected to percutaneous treatment of lumbar herniated disc. 733 of these were treated through enzymatic nucleolysis with chymopapain, for a total 883 levels. Chemonucleolysis was carried out on 733 patients (79.8%). Automated discectomy has been carried out in 185 cases (20.1%). Chemonucleolysis has led to the resolution of the symptoms in a high percentage of cases (82.2%). Nucleotomy has proved to be an effective method in 74.6% of cases. (author). 7 refs, 6 figs, 1 tab.

  1. Likelihood inference for unions of interacting discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisova, K.

    2010-01-01

    This is probably the first paper which discusses likelihood inference for a random set using a germ-grain model, where the individual grains are unobservable, edge effects occur and other complications appear. We consider the case where the grains form a disc process modelled by a marked point...... with respect to a given marked Poisson model (i.e. a Boolean model). We show how edge effects and other complications can be handled by considering a certain conditional likelihood. Our methodology is illustrated by analysing Peter Diggle's heather data set, where we discuss the results of simulation......-based maximum likelihood inference and the effect of specifying different reference Poisson models....

  2. CT-guided percutaneous laser disc decompression with Ceralas D, a diode laser with 980-nm wavelength and 200-{mu}m fiber optics

    Energy Technology Data Exchange (ETDEWEB)

    Gevargez, A. [Department of Radiology and Microtherapy, University Witten/Herdecke, Bochum (Germany); Groenemeyer, D.W.H. [Department of Radiology and Microtherapy, University Witten/Herdecke, Bochum (Germany); Entwicklungs- und Forschungszentrum fuer Mikrotherapie, Bochum (Germany); Czerwinski, F. [Entwicklungs- und Forschungszentrum fuer Mikrotherapie, Bochum (Germany)

    2000-08-01

    The aim of this study was to evaluate the compact, portable Ceralas-D diode laser (CeramOptec; 980+30 nm wavelength, 200-{mu}m optical fiber) concerning clinical usefulness, handling, and clinical results in the CT-guided treatment of herniated lumbar discs. The positioning of the canula in intradiscal space, the placement of the laser fiber into the disc through the lying canula, and the vaporization itself were carried out under CT-guidance. Due to the thin fiber optic, it was possible to use a thin 23-gauge canula. The laser procedure was performed in 0.1- to 1-s shots with 1-s pulse pause and 4-W power output. A total of 1650-2300 J was applied on each percutaneous laser disc decompression (PLDD). Results in 26 patients were established with a visual-analogue scale (VAS). On the follow-up examinations, 46% of the patients were absolutely pain free (>85% VAS) and fully active in everyday life after 4 postoperative weeks. Thirty-one percent of patients were relieved of the leg pain but had occasional back pain without sensorimotor impairment. Fifteen percent sensed a slight alleviation (>50% VAS) of the radiate pain. Eight percent did not experience radicular or pseudo-radicular pain alleviation (<25% VAS). Cerales-D proves to be an efficient tool for CT-guided PLDD on non-sequestered herniated lumbar discs. (orig.)

  3. Genome-Wide Association Study in Dachshund: Identification of a Major Locus Affecting Intervertebral Disc Calcification

    DEFF Research Database (Denmark)

    Mogensen, Mette Sloth; Karlskov-Mortensen, Peter; Proschowsky, Helle Friis

    2011-01-01

    Intervertebral disc calcification and herniation commonly affects Dachshund where the predisposition is caused by an early onset degenerative process resulting in disc calcification. A continuous spectrum of disc degeneration is seen within and among clog breeds, suggesting a multifactorial etiol...

  4. Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation.

    Science.gov (United States)

    Matuska, Andrea M; Muller, Stephen; Dolwick, M Franklin; McFetridge, Peter S

    2016-04-01

    The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs. Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs. Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface. The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Retinal Nerve Fiber Layer Protrusion Associated with Tilted Optic Discs.

    Science.gov (United States)

    Chiang, Jaclyn; Yapp, Michael; Ly, Angelica; Hennessy, Michael P; Kalloniatis, Michael; Zangerl, Barbara

    2018-03-01

    This study resulted in the identification of an optic nerve head (ONH) feature associated with tilted optic discs, which might potentially contribute to ONH pathologies. Knowledge of such findings will enhance clinical insights and drive future opportunities to understand disease processes related to tilted optic discs. The aim of this study was to identify novel retinal nerve fiber layer (RNFL) anomalies by evaluating tilted optic discs using optical coherence tomography. An observed retinal nerve fiber protrusion was further investigated for association with other morphological or functional parameters. A retrospective review of 400 randomly selected adult patients with ONH examinations was conducted in a referral-only, diagnostic imaging center. After excluding other ONH pathologies, 215 patients were enrolled and evaluated for optic disc tilt and/or torsion. Gross anatomical ONH features, including size and rim or parapapillary region elevation, were assessed with stereoscopic fundus photography. Optical coherence tomography provided detailed morphological information of individual retinal layers. Statistical analysis was applied to identify significant changes between individual patient cohorts. A dome-shaped hyperreflective RNFL bulge, protruding into the neurosensory retina at the optic disc margins, was identified in 17 eyes with tilted optic discs. Available follow-up data were inconclusive regarding natural changes with this ONH feature. This RNFL herniation was significantly correlated with smaller than average optic disc size (P = .005), congenital disc tilt (P optic discs, which has not previously been assessed as an independent ONH structure. The feature is predominantly related to congenital crowded, small optic discs and variable between patients. This study is an important first step to elucidate diagnostic capabilities of tilted disc morphological changes and understanding associated functional deficits.

  6. Development of a whole disc organ culture system to study human intervertebral disc

    Science.gov (United States)

    Parolin, M.; Gawri, R.; Mwale, F.; Steffen, T.; Roughley, P.; Antoniou, J.; Jarzem, P.; Haglund, L.; Ouellet, J.

    2010-01-01

    Study type: Basic science Objective: Low back pain is one of the most common health problems1 and is strongly associated with intervertebral disc degeneration, (IVD). Current treatments remove the symptoms without reversing or even retarding the underlying problem. Development of new therapy for the regeneration of the degenerative IVD is complicated by the lack of a validated long-term organ culture model in which therapeutic candidates can be studied. The object of this study was to develop, optimize, and validate an organ culture model for human IVD, allowing for the study of degeneration and the potential for regeneration of the human IVD. Methods: From eleven donors, an average of 5–6 IVDs were obtained. Inclusion criteria were; age between 50 and 70 years old, no history of cancer, chemotherapy, diabetes, or liver cirrhosis. An x-ray of the harvested spine was done to assess the grade of degeneration. Three different methods for isolating the discs were studied: with bony endplate (BEP), without endplate (NEP), and with cartilage endplate (CEP). Discs were cultured for 4 weeks without external load, in Dulbecco's modified eagle media with glucose and fetal bovine serum (FBS). Four different combinations of concentrations of glucose and FBS were compared: low glucose-low FBS, low glucose-high FBS, high glucose-low FBS, and high glucose-high FBS.2 Short-term cultures (1 week) were performed to compare the cell viability of the three methods of isolating the discs. Swelling potential on NEP and CEP discs from the same donor were evaluated. After four weeks of culture, a 4 mm punch was taken from CEP discs and cell viability was evaluated using a live/dead assay with confocal microscopy. Results: Analyzing the potential of swelling in CEP discs, there was an increase in volume to a maximum of 25% and retention of shape and morphology. Whereas in NEP discs, there was an excessive deformation and a two-fold time increase in volume than CEP discs. The cell

  7. The Drosophila Z-disc protein Z(210) is an adult muscle isoform of Zasp52, which is required for normal myofibril organization in indirect flight muscles.

    Science.gov (United States)

    Chechenova, Maria B; Bryantsev, Anton L; Cripps, Richard M

    2013-02-08

    The Z-disc is a critical anchoring point for thin filaments as they slide during muscle contraction. Therefore, identifying components of the Z-disc is critical for fully comprehending how myofibrils assemble and function. In the adult Drosophila musculature, the fibrillar indirect flight muscles accumulate a >200 kDa Z-disc protein termed Z(210), the identity of which has to date been unknown. Here, we use mass spectrometry and gene specific knockdown studies, to identify Z(210) as an adult isoform of the Z-disc protein Zasp52. The Zasp52 primary transcript is extensively alternatively spliced, and we describe its splicing pattern in the flight muscles, identifying a new Zasp52 isoform, which is the one recognized by the Z(210) antibody. We also demonstrate that Zasp52 is required for the association of α-actinin with the flight muscle Z-disc, and for normal sarcomere structure. These studies expand our knowledge of Zasp isoforms and their functions in muscle. Given the role of Zasp proteins in mammalian muscle development and disease, our results have relevance to mammalian muscle biology.

  8. The cellular memory disc of reprogrammed cells.

    Science.gov (United States)

    Anjamrooz, Seyed Hadi

    2013-04-01

    The crucial facts underlying the low efficiency of cellular reprogramming are poorly understood. Cellular reprogramming occurs in nuclear transfer, induced pluripotent stem cell (iPSC) formation, cell fusion, and lineage-switching experiments. Despite these advances, there are three fundamental problems to be addressed: (1) the majority of cells cannot be reprogrammed, (2) the efficiency of reprogramming cells is usually low, and (3) the reprogrammed cells developed from a patient's own cells activate immune responses. These shortcomings present major obstacles for using reprogramming approaches in customised cell therapy. In this Perspective, the author synthesises past and present observations in the field of cellular reprogramming to propose a theoretical picture of the cellular memory disc. The current hypothesis is that all cells undergo an endogenous and exogenous holographic memorisation such that parts of the cellular memory dramatically decrease the efficiency of reprogramming cells, act like a barrier against reprogramming in the majority of cells, and activate immune responses. Accordingly, the focus of this review is mainly to describe the cellular memory disc (CMD). Based on the present theory, cellular memory includes three parts: a reprogramming-resistance memory (RRM), a switch-promoting memory (SPM) and a culture-induced memory (CIM). The cellular memory arises genetically, epigenetically and non-genetically and affects cellular behaviours. [corrected].

  9. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  10. The truncation of stellar discs : The magnetic hypothesis

    NARCIS (Netherlands)

    Battaner, E; Florido, E; Jimenez-Vicente, J

    We propose a hypothesis of the truncation of stellar discs based on the magnetic model of the rotation curve of spiral galaxies. Once the disc had formed and acquired its present structure, approximately, three balanced forces were acting on the initial gas: gravity and magnetic forces, inwards, and

  11. Spontaneous and complete regression of a thoracic disc herniation

    International Nuclear Information System (INIS)

    Coevoet, V.; Benoudiba, F.; Doyon, D.; Lignieres, C.; Said, G.

    1997-01-01

    Spontaneous regression of disc herniation is well known but the mechanism is not clear. Some hypotheses have been made. We present here a large thoracic disc herniation diagnosed by MRI which completely regressed one year after a medical treatment with complete amendment of symptoms. (authors)

  12. Comparative Study on The Potency of Antibiotic Discs With ...

    African Journals Online (AJOL)

    Our results showed that antibiotics disc was more effective than the commercially sold antibiotics and that both organisms were resistant to Ampicillin but susceptible to Gentamicin and. Ciprofloxacin. Keywords: Potency, Antibiotics, Disc Isolates, Urinary tract. INTRODUCTION. The urinary system is structured in a way that.

  13. Delivery systems for the treatment of degenerated intervertebral discs

    NARCIS (Netherlands)

    Blanquer, S. B. G.; Grijpma, D. W.; Poot, A. A.

    The intervertebral disc (ND) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production,

  14. Assembling Modules to the End-cap SCT Discs

    CERN Document Server

    Jackson, JN; Sutcliffe, P

    2002-01-01

    A major step in the construction of the SCT end-caps is the process of mounting the modules onto the discs and testing them. This note contains a description of the proposed assembly procedure and the design of the necessary jig to assemble inner, middle, and outer modules to the end-cap disc structure. Results obtained using prototype jigs are described.

  15. Optic Disc Coloboma in Two Nigerian Siblings: Case Report and ...

    African Journals Online (AJOL)

    with inferior disc excavation, superior wedge of the pink neuro‑retinal rim as well as a temporal optic disc pit. No systemic features of syndromes associated with. ODCs and intellectual disability were present in both patients. The younger sibling an 8‑year‑old girl later presented to the eye clinic with a 5‑month history of poor.

  16. Spine imaging after lumbar disc replacement: pitfalls and current recommendations

    OpenAIRE

    Robinson, Yohan; Sand?n, Bengt

    2009-01-01

    Abstract Background Most lumbar artificial discs are still composed of stainless steel alloys, which prevents adequate postoperative diagnostic imaging of the operated region when using magnetic resonance imaging (MRI). Thus patients with postoperative radicular symptoms or claudication after stainless steel implants often require alternative diagnostic procedures. Methods Possible complications of lumbar total disc replacement (TDR) are reviewed from the available literature and imaging reco...

  17. Tissue Engineering a Biological Repair Strategy for Lumbar Disc Herniation

    Science.gov (United States)

    O'Connell, Grace D.; Leach, J. Kent; Klineberg, Eric O.

    2015-01-01

    Abstract The intervertebral disc is a critical part of the intersegmental soft tissue of the spinal column, providing flexibility and mobility, while absorbing large complex loads. Spinal disease, including disc herniation and degeneration, may be a significant contributor to low back pain. Clinically, disc herniations are treated with both nonoperative and operative methods. Operative treatment for disc herniation includes removal of the herniated material when neural compression occurs. While this strategy may have short-term advantages over nonoperative methods, the remaining disc material is not addressed and surgery for mild degeneration may have limited long-term advantage over nonoperative methods. Furthermore, disc herniation and surgery significantly alter the mechanical function of the disc joint, which may contribute to progression of degeneration in surrounding tissues. We reviewed recent advances in tissue engineering and regenerative medicine strategies that may have a significant impact on disc herniation repair. Our review on tissue engineering strategies focuses on cell-based and inductive methods, each commonly combined with material-based approaches. An ideal clinically relevant biological repair strategy will significantly reduce pain and repair and restore flexibility and motion of the spine. PMID:26634189

  18. Demographical Aspects of Central Large Lumbar Disc Herniation.

    Science.gov (United States)

    Topuz, Kivanc; Eroglu, Ahmet; Simsek, Hakan; Atabey, Cem; Cetinkal, Ahmet; Colak, Ahmet

    2016-01-01

    The purpose of this study was to investigate the risk factors for the development of the central large disc herniations and to compare the demographic data between central mass prolapse and broad-based central disc herniation. Between 2002 and 2007, 1630 patients underwent surgery and a large disc herniation was the main problem in 59 patients (3.6%). We performed a retrospective analysis of the demographic data of these patients. Magnetic resonance (MR) images were evaluated according to the disc type and level. Variables were evaluated both at baseline and follow-up, with special emphasis on physical job characteristics, sports activities, and MR - based morphologic findings. Central large disc herniation was diagnosed in 59 patients consisting of 41 males and 18 females. The average age was 34.7 years. 36 patients had a central mass prolapse that occupied more than 50% of the spinal canal. Intraoperative observations confirmed that 29 out of 36 central disc prolapse patients (80.5%) had intact posterior longitudinal ligaments. Interestingly, the condition in these 29 patients was found to have a direct relation with age and occupation or other body training sports activities. The size of the large central disc herniation, physical activity, age and gender are major factors in the development of disc herniation.

  19. Spontaneous regression of lumbar herniated disc Case presentation

    Directory of Open Access Journals (Sweden)

    Chiriac A.

    2015-12-01

    Full Text Available Intervertebral disc herniation is a common disease that usually requires surgical intervention. However, in some cases, neurological symptoms may improve with conservative treatment. In this article, we present a case with spontaneous regression of extruded lumbar herniated disc correlated with clinical improvement and documented with follow up MRI studies.

  20. Surgical treatment of foraminal herniated disc of the lumbar spine

    OpenAIRE

    Halikov Shavkatbek; Abduhalikov Alimjon Karimjanovich

    2017-01-01

    Herniated lumbar intervertebral disc have a significant impact on both the patient’s life as well, and because of the high prevalence and economic impact on society as a whole. Designed scheduling algorithm foraminal hernia surgical treatment of lumbar intervertebral disc, based on the preoperative detection of compressing factors allows to define differentiated indications for decompressive or decompressive-stabilizing surgery.

  1. Disc Activities in Physical Education: A Comprehensive Approach

    Science.gov (United States)

    Cramer, Stanley J.

    2017-01-01

    Nearly everyone who throws a disc associates the activity with fun. Over the years, multiple disc games and activities have been invented, combining fun and learning. These are games that many individuals are likely to continue playing long after they have left school and are worthy of being included in a contemporary physical education program.…

  2. 21 CFR 872.3970 - Interarticular disc prosthesis (interpositional implant).

    Science.gov (United States)

    2010-04-01

    ... implant). 872.3970 Section 872.3970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3970 Interarticular disc prosthesis (interpositional implant). (a) Identification. An interarticular disc prosthesis...

  3. Spectral properties of the accretion discs around rotating black holes

    Indian Academy of Sciences (India)

    Samir Mandal

    2018-02-10

    Feb 10, 2018 ... Abstract. We study the radiation properties of an accretion disc around a rotating black hole. We solve the hydrodynamic equations and calculate the transonic solutions of accretion disc in the presence of shocks. Then we use these solutions to generate the radiation spectrum in the presence of radiative ...

  4. Goddard Earth Science Data and Information Center (GES DISC)

    Science.gov (United States)

    Kempler, Steve

    2016-01-01

    The GES DIS is one of 12 NASA Earth science data centers. The GES DISC vision is to enable researchers and educators maximize knowledge of the Earth by engaging in understanding their goals, and by leading the advancement of remote sensing information services in response to satisfying their goals. This presentation will describe the GES DISC approach, successes, challenges, and best practices.

  5. Microfabrication and Magnetic Particle Spectrometry of Magnetic Discs

    NARCIS (Netherlands)

    Löthman, Per Arvid; Janson, T.G.; Klein, Yannick Philippe; Blaudszun, André-René; Ledwig, Michael; Abelmann, Leon

    2017-01-01

    We report on the fabrication of dispersions of Au/Ni81Fe19/Au magnetic discs with two and three micrometer diameter and thickness in the order of hundred nanometers. The magnetisation reversal of the discs was analysed on a time-scale of an hour as well as a few milliseconds to asses their

  6. Presumed optic disc melanocytoma in a young Nigerian: a ...

    African Journals Online (AJOL)

    Optic disc melanocytoma (ODM) is a rare, benign, deeply pigmented ocular tumor arising from melanocytes within the optic disc or from any part of the uvea. It occurs more in dark skinned individuals and females. We report a 17‑year‑old female who presented to our outpatient department with a history of poor distant vision ...

  7. The value of MRI in the preoperative diagnosis of cervical disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Kuroki, Takefusa; Kumano, Kiyoshi; Hirabayashi, Shigeru; Takahashi, Ryuji; Inasaka, Riki (Kanto Rosai Hospital, Tokyo (Japan))

    1991-12-01

    To determine whether or not magnetic resonance (MR) imaging would become an alternative to conventional myelography in the preoperative diagnosis of cervical disc herniation, MR images of 13 patients were retrospectively reviewed. MR imaging revealed herniated one disc, 2 discs, and 3 discs in 4, 6, and 3 patients, respectively. When herniation confined to one disc was consistent with clinical manifestations, MR imaging alone was capable of determining the disc involved in herniation. MR imaging was, however, of limited value in determining the responsible disc for herniation when there were two or more herniated discs on MR images. (N.K.).

  8. CT-discography; diagnostic accuracy in lumbar disc herniation and significance of induced pain during procedure

    Energy Technology Data Exchange (ETDEWEB)

    Jin, En Hao [Yan Bian Medical College, Beijing (China); Chung, Tae Sub; Jeong, Mi Gyoung; Kim, Young Soo; Roh, Sung Woo [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

    1996-01-01

    To evaluate the usefulness and the accuracy of CT-discography in lumbar disc disease by analyzing the findings of CT-discogram and types of evoked pain during the procedure. CT-discograms were retrospectively evaluated in 47 intervertebral discs of 20 patients with multilevel involvement of lumbar disc diseases. In 28 herniated discs confirmed at surgery, the findings of CT-discogram (28 disc levels/20 patients), MRI(23/16) and CT(21/15) were comparatively analysed. The type of pain after infusion of contrast media during CT-discography was compared with that prior to the procedure. The accuracy for determining types of the herniated lumbar disc when compared with post-operative results was 96.4%(27 discs/28 discs) in the CT-discogram, 82.6%(19 discs/23 discs) in MRI and 71.4%(15 discs/21 discs) in the CT scan. Pains encountered during discography were radiating pain in 12 discs and back pain in 24 discs. CT-discography was especially helpful in 10 patients with multilevel involvement of the lumbar disc diseases to evaluate the exact location of diseased disc(s) that provoked the pain. CT-discography is a highly accurate method in diagnosis of the herniated lumbar intervertebral discs and is very useful in determining the precise location related to the development of pain in such cases.

  9. Magnetic resonance imaging for each type of herniated cervical intervertebral disc

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ham Gyum [Ansan 1 College, Ansan (Korea, Republic of)

    2000-04-15

    The classification of herniated intervertebral cervical disc types are clinically important, as treatment methods would be slightly different according to the specific type of the herniated disc. 423 patients who suffered from herniated intervertebral cervical discs were tested with Magnetic Resonance Imaging (MRI), to distinguish the type of the herniated discs. The following are the results: The age of the patients tested ranged from 16 to 75 years old and the mean age of the patients was 41.4 years of age. There were twice as many male patients with a ratio of 288: 135 men to women. 101 patients suffered from single herniated discs while 322 patients suffered from multi-herniated discs. Of single herniated disc injuries. 52 patients had protruded discs (52%) while 25 patients had extruded discs (25%). 21 Patients (21%) had herniated intervertebral discs between C{sub 4} {approx} C{sub 5} and 51 patients (50%) and had the same injury between C{sub 5} and C{sub 6}. Of multi-herniated disc injuries. 140 patients had protruded discs (44%). while 45 patients had extruded discs (14%). 54 patients had both protruded and extruded discs (17%). 36 patients (11%). herniated discs C{sub 3} {approx} C{sub 6}: 69 patients (21%). herniated discs C{sub 3} {approx} C{sub 7}: 47 patients (15%) herniated discs C{sub 4} {approx} C{sub 6} and 67 patients (20%) herniated discs C{sub 5} {approx} C{sub 7}.

  10. CT-discography; diagnostic accuracy in lumbar disc herniation and significance of induced pain during procedure

    International Nuclear Information System (INIS)

    Jin, En Hao; Chung, Tae Sub; Jeong, Mi Gyoung; Kim, Young Soo; Roh, Sung Woo

    1996-01-01

    To evaluate the usefulness and the accuracy of CT-discography in lumbar disc disease by analyzing the findings of CT-discogram and types of evoked pain during the procedure. CT-discograms were retrospectively evaluated in 47 intervertebral discs of 20 patients with multilevel involvement of lumbar disc diseases. In 28 herniated discs confirmed at surgery, the findings of CT-discogram (28 disc levels/20 patients), MRI(23/16) and CT(21/15) were comparatively analysed. The type of pain after infusion of contrast media during CT-discography was compared with that prior to the procedure. The accuracy for determining types of the herniated lumbar disc when compared with post-operative results was 96.4%(27 discs/28 discs) in the CT-discogram, 82.6%(19 discs/23 discs) in MRI and 71.4%(15 discs/21 discs) in the CT scan. Pains encountered during discography were radiating pain in 12 discs and back pain in 24 discs. CT-discography was especially helpful in 10 patients with multilevel involvement of the lumbar disc diseases to evaluate the exact location of diseased disc(s) that provoked the pain. CT-discography is a highly accurate method in diagnosis of the herniated lumbar intervertebral discs and is very useful in determining the precise location related to the development of pain in such cases

  11. Use of polystyrene spin-coated compact discs for microimmunoassaying

    International Nuclear Information System (INIS)

    Tamarit-Lopez, Jesus; Morais, Sergi; Puchades, Rosa; Maquieira, Angel

    2008-01-01

    The analytical potential of polystyrene (PS) spin-coated modified compact discs (CDs) surface as platforms for the development of microarray immunoassays is presented. The surface maintained the optical characteristics of compact discs, obtaining a transparent and smooth film polymer of 70 nm thickness, the track being read (λ 780 nm) without errors in a commercial CD reader/writer. The analytical capability of the methodology was demonstrated through an analysis of a neurotoxic compound (2560 spots per disc), reaching 0.08 μg L -1 as limit of detection. These figures demonstrate the enormous potential of using PS spin-coated compact discs in combination with CD players as an easy-to-operate and portable device to develop lab-on-a-disc analytical applications

  12. The radiological diagnosis of thoracolumbar disc disease in the Dachshund

    International Nuclear Information System (INIS)

    Kirberger, R.M.; Roos, C.J.; Lubbe, A.M.

    1992-01-01

    The accuracy of survey radiographs in the diagnosis of acute thoracolumbar disc disease in 36 Dachshunds was determined by comparison with lumbar myelographic findings using iohexol. The value of making radiographs immediately after injection of contrast medium and the effectiveness of oblique radiographs in determining the exact circumferential distribution of extruding or protruding disc material were assessed. The presence of a double contrast medium column, resistance to injection and the presence of cerebrospinal fluid flow during needle placement was also evaluated. The location of the affected disc was accurately determined on survey radiographs in only 26 dogs. The myelographic technique used in this study resulted in the correct intervertebral space being identified, together with the exact circumferential distribution of disc material, in 35 dogs. Survey radiographs alone are inadequate for localization of protruding or extruding disc material

  13. Gas Modelling in the Disc of HD 163296

    Science.gov (United States)

    Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W. -F.; Isella, A.; Roberge, A.; hide

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of approx. 4Myr, with evidence of a circumstellar disc extending out to approx. 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [Oi] 63 m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the CO-12 3-2, 2-1 and CO-13 J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry

  14. The presence and absence of lymphatic vessels in the adult human intervertebral disc: relation to disc pathology

    Energy Technology Data Exchange (ETDEWEB)

    Kliskey, Karolina; Williams, Kelly; Yu, J.; Urban, Jill; Athanasou, Nick [University of Oxford, Nuffield Department of Orthopaedic, Rheumatology and Musculoskeletal Science, Oxford (United Kingdom); Jackson, David [Weatherall Institute of Molecular Medicine, Human Immunology Unit, Oxford (United Kingdom)

    2009-12-15

    Although the normal adult human intervertebral disc is considered to be avascular, vascularised cellular fibrous tissue can be found in pathological conditions involving the disc such as disc herniation. Whether lymphatics vessels form a component of this reparative tissue is not known as the presence or absence of lymphatics in herniated and normal disc tissue is not known. We examined spinal tissues and discectomy specimens for the presence of lymphatics. The examination used immunohistochemistry to identify the specific lymphatic endothelial cell markers, podoplanin and LYVE1. Lymphatic vessels were not found in the nucleus pulposus or annulus fibrosus of intact, non-herniated lumbar and thoracic discs but were present in the surrounding ligaments. Ingrowth of fibrous tissue was seen in 73% of herniated disc specimens of which 36% contained LYVE1+/podoplanin + lymphatic vessels. Lymphatic vessels were not seen in the sacrum and coccyx or biopsies of four sacrococcygeal chordomas, but they were noted in surrounding extra-osseous fat and fibrous tissue at the edge of the infiltrating tumour. Our findings indicate that lymphatic vessels are not present in the normal adult intervertebral disc but that, when there is extrusion of disc material into surrounding soft tissue, there is ingrowth of reparative fibrous tissue containing lymphatic vessels. Our findings also indicate that chordoma, a tumour of notochordal origin, spreads to regional lymph nodes via lymphatics in para-spinal soft tissues. (orig.)

  15. Migration patterns of herniated disc fragments: a study on 1,020 patients with extruded lumbar disc herniation.

    Science.gov (United States)

    Daghighi, Mohammad Hussein; Pouriesa, Masoud; Maleki, Mirjalil; Fouladi, Daniel Fadaei; Pezeshki, Mohammad Zakaria; Mazaheri Khameneh, Ramin; Bazzazi, Amir Mohammad

    2014-09-01

    Herniated disc fragments are known to migrate in various directions within the spinal canal. To date, no comprehensive studies have been undertaken to examine the migration patterns of herniated disc material using a standard nomenclature and classification system. To report migration patterns of extruded lumbar disc fragments. A review of magnetic resonance (MR) images. A total of 1,020 consecutive Azeri patients with symptomatic extruded lumbar intervertebral disc herniation. Migration patterns of extruded lumbar disc fragments in vertical and horizontal planes and their association with age, gender, body mass index (BMI), and the level of herniation. High-quality axial and sagittal MR images of the lumbar spine were used. Disc material that was displaced away from the site of extrusion, regardless of continuity, was considered "migrated." The migration patterns observed were rostral or caudal in the vertical plane and central, paracentral, subarticular, foraminal, or extraforaminal in the horizontal plane. In the vertical plane, rostral and caudal migrations were observed in 27.8% and 72.2% of the patients, respectively. The number of rostral migrations increased significantly with increasing age and in higher levels in the lumbar spine (pherniation and migration pattern in the horizontal plane. Caudal and paracentral migrations are the most common patterns of migration in patients with extruded lumbar disc herniation in the vertical and horizontal planes, respectively. Age and the level of herniation may affect the migration patterns of herniated lumbar disc material. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Analysis of trace element in intervertebral disc by Atomic Absorption Spectrometry techniques in degenerative disc disease in the Polish population

    Directory of Open Access Journals (Sweden)

    Andrzej Nowakowski

    2015-05-01

    This study is the first to our knowledge that profiles the elements in intervertebral disc in patients with degenerative changes. We have confirmed significant differences between the trace element contents in intervertebral disc and other tissue. It can be ground for further investigation.

  17. The presence and absence of lymphatic vessels in the adult human intervertebral disc: relation to disc pathology

    International Nuclear Information System (INIS)

    Kliskey, Karolina; Williams, Kelly; Yu, J.; Urban, Jill; Athanasou, Nick; Jackson, David

    2009-01-01

    Although the normal adult human intervertebral disc is considered to be avascular, vascularised cellular fibrous tissue can be found in pathological conditions involving the disc such as disc herniation. Whether lymphatics vessels form a component of this reparative tissue is not known as the presence or absence of lymphatics in herniated and normal disc tissue is not known. We examined spinal tissues and discectomy specimens for the presence of lymphatics. The examination used immunohistochemistry to identify the specific lymphatic endothelial cell markers, podoplanin and LYVE1. Lymphatic vessels were not found in the nucleus pulposus or annulus fibrosus of intact, non-herniated lumbar and thoracic discs but were present in the surrounding ligaments. Ingrowth of fibrous tissue was seen in 73% of herniated disc specimens of which 36% contained LYVE1+/podoplanin + lymphatic vessels. Lymphatic vessels were not seen in the sacrum and coccyx or biopsies of four sacrococcygeal chordomas, but they were noted in surrounding extra-osseous fat and fibrous tissue at the edge of the infiltrating tumour. Our findings indicate that lymphatic vessels are not present in the normal adult intervertebral disc but that, when there is extrusion of disc material into surrounding soft tissue, there is ingrowth of reparative fibrous tissue containing lymphatic vessels. Our findings also indicate that chordoma, a tumour of notochordal origin, spreads to regional lymph nodes via lymphatics in para-spinal soft tissues. (orig.)

  18. Resolving HD 100546 disc in the mid-infrared: Small inner disc and asymmetry near the gap

    NARCIS (Netherlands)

    Panić, O.; Ratzka, T.; Mulders, G.D.; Dominik, C.; van Boekel, R.; Henning, T.; Jaffe, W.J.; Min, M.

    2014-01-01

    Context. A region of roughly half of the solar system scale around the star HD 100546 is known to be largely cleared of gas and dust, in contrast to the outer disc that extends to about 400 AU. However, some material is observed in the immediate vicinity of the star, called the inner disc. Studying

  19. Minimally invasive transmuscular approach for the treatment of lumbar herniated disc: far lateral lumbar disc herniation: a clinical study. Applications for cervical and thoracic disc herniation.

    Science.gov (United States)

    Peltier, E; Blondel, B; Dufour, H; Fuentes, S

    2013-06-01

    In this study, we are using a recently developed method: a minimally invasive retractor system and an operating microscope to treat far lateral lumbar herniated disc. This method decreases tissue dissection and blood loss, and improves postoperative recovery. This is a retrospective study of 46 patients, there was 25 female and 21 male. They all underwent minimal invasive surgery. The average age was 56 years old (19-83 years). Lumbar disc herniation is a common pathology. Far lateral disc herniation accounts for 2.6% to 11.2% of all lumbar disc herniation. A few surgical techniques have been describes to treat this type of disc pathology. All patients were operated under general anesthesia. The fluoroscopic guidance was absolutely necessary. A 12-15 mm skin incision was made on the side of the disc herniation (30 mm from the midline). Then, we inserted a tubular retractor system (muscle splitting approach) followed by a 14 mm diameter-working channel. Under operating microscope the pars interarticularis was dreamed to expose the nerve root and the disc. After removing the intertransverse ligament, we removed the herniated disc. The average time of surgery was 55 min. The operating time decreased with the experience of the surgical team. Postoperatively the radicular pain was around 2 (using an analogical visual scale), over 7 preoperatively. The length of hospitalization was 3 days. There were no complications in our study. The average follow-up was 2 years (6-36 months). There was no complication, no postoperative infection. This technique combines the advantages of endoscopic surgery and microscope guided surgery (3D vision) and provides good functional results in this study.

  20. A new dynamic six degrees of freedom disc-loading simulator allows to provoke disc damage and herniation.

    Science.gov (United States)

    Wilke, Hans-Joachim; Kienle, Annette; Maile, Sebastian; Rasche, Volker; Berger-Roscher, Nikolaus

    2016-05-01

    The cause of disc herniation is not well understood yet. It is assumed that heavy lifting and extreme postures can cause small injuries starting either in the inner anulus or from the outside close to the endplate. Such injuries are accumulated over years until its structure is weakened and finally a single loading event leads to a sudden failure of the last few intact lamellae. This paper describes a novel, custom-developed dynamic 6-DOF disc-loading simulator that allows complex loading to provoke such disc damage and herniations. The machine's axes are driven by six independent servomotors providing high loads (10 kN axial compression, 2 kN shear, 100 Nm torque) up to 5 Hz. A positional accuracy test was conducted to validate the machine. Subsequently, initial experiments with lumbar ovine motion segments under complex loading were performed. After testing, the discs were examined in an ultra-high field MRI (11.7 T). A three-dimensional reconstruction was performed to visualise the internal disc lesions. Validation tests demonstrated positioning with an accuracy of ≤0.08°/≤0.026 mm at 0.5 Hz and ≤0.27°/≤0.048 mm at 3.0 Hz with amplitudes of ±17°/±2 mm. Typical failure patterns and herniations could be provoked with complex asymmetrical loading protocols. Loading with axial compression, flexion, lateral bending and torsion lead in 8 specimens to 4 herniated discs, two protrusions and two delaminations. All disc failures occurred in the posterior region of the disc. This new dynamic disc-loading simulator has proven to be able to apply complex motion combinations and allows to create artificial lesions in the disc with complex loading protocols. The aim of further tests is to better understand the mechanisms by which disc failure occurs at the microstructural level under different loading conditions. Visualisation with ultra-high field MRI at different time points is a promising method to investigate the gradual development of such lesions

  1. Intraosseous disc prolapse: A diagnostic puzzle

    Directory of Open Access Journals (Sweden)

    Parasnis Rajesh

    2006-01-01

    Full Text Available Background : Schmorl′s node or intraosseous disc prolapse is herniation of the nucleus pulposus material through the vertebral end plates. Presence of Schmorl′s nodes as end plate lesions following trauma, tumours and osteoporosis further complicates diagnosis. The present study was done to understand diagnosis and approach to management of symptomatic Schmorl′s nodes. Methods : During a period of three years we came across 14 patients who presented with severe back pain. Conventional radiographs, CT Scans and MRI showed the presence of end plate lesions with varied radiological appearance. The first group, comprising of seven patients had lytic lesions without any sclerosis on only one side of the intervertebral disc as seen on the CT scan. The second group comprising of five patients had sclerotic lesions with new bone formation associated with disc space reduction. The two patients in the third group showed a combined lytic and sclerotic lesion without any soft tissue changes. MRI of eleven patients revealed hypointense lesion on T 1 and T 2 weighted images with surrounding zone of hyper intensity on T 2 weighted images. The remaining three patients, did not have this hyper intense zone on T 2 weighted images . In five patients multiple Schmorl′s nodes were observed. Diagnosis of symptomatic Schmorl′s nodes was mainly done by exclusion. All patients were given rest and anti-inflammatory drugs followed by exercises. Results : The first two groups of patients responded to the treatment and had complete relief of symptoms but both the patients in third group had persistent symptoms. MRI repeated after eight weeks showed an enhancing lesion with prevertebral soft tissue. A transpedicular core biopsy proved the lesion to be tuberculosis in one patient. Anti Koch′s therapy was promptly started and follow up study showed resolution of the lesions. At the end of the study period all the patients were asymptomatic and returned to their

  2. Genetic Alterations in Intervertebral Disc Disease

    Directory of Open Access Journals (Sweden)

    Nikolay L. Martirosyan

    2016-11-01

    Full Text Available Background: Intervertebral disc degeneration (IVDD is considered a multifactorial disease. The last two decades of research strongly demonstrate that genetic factors contribute about 75% of the IVDD etiology. Recent total genome sequencing studies have shed light on the various single nucleotide polymorphisms (SNPs that are associated with IVDD.Aim: This review explores and presents updated information about the diversity of genetic factors in the inflammatory, degradative, homeostatic, and structural systems involved in the IVDD.Results: SNPs in the genes coding for structural proteins linked with IVDD or disc bulging include the Sp1 polymorphism of COL1A1, Trp3 polymorphism of COL9A3, several polymorphisms of COL11A1 and COL11A2, and a variable number tandem repeat polymorphism of ACAN. The rs4148941 SNP of CHST3 coding for an aggrecan sulfation enzyme is also associated with IVDD. The FokI, TaqI, and ApaI SNPs of the vitamin D receptor gene that is involved in chondrocyte functioning are also associated with IVDD. SNPs relevant to cytokine imbalance in IVDD include 889C/T of IL1a and 15T/A, as well as other SNPs (rs1800795, rs1800796, and rs1800797, of IL6, with effects limited to certain genders and populations. SNPs in collagenase genes include -1605G/D (guanine insertion/deletion of MMP1, -1306C/T of MMP2, -1562C/T and a 5-adenosine (5A variant (in the promotor region of MMP3, -1562C/T of MMP9, and -378T/C of MMP-14. SNPs in aggrecanase genes include 1877T/U of ADAMTS-4 and rs162509 of ADAMTS-5. Among the apoptosis-mediating genes, 1595T/C of the caspase 9 gene, 1525A/G and 1595T/C of the TRAIL gene, and 626C/G of the death receptor 4 gene (DR4 are SNPs associated with IVDD. Among the growth factors involved in disc homeostasis, the rs4871857 SNP of GDF5 was associated with IVDD. VEGF SNPs -2578C/A and -634G/C could foster neovascularization observed in IVDD.Conclusion: Improved understanding of the numerous genetic variants behind various

  3. Different Expression of Extracellular Matrix Genes : Primary vs. Recurrent Disc Herniation

    Science.gov (United States)

    Kuh, Sung-Uk; Kwon, Young-Min; Chin, Dong-Kyu; Jin, Byung-Ho; Cho, Yong-Eun

    2010-01-01

    Objective Recurrent lumbar disc herniation has been reported to occur in 5% to 15% of surgically treated primary lumbar disc herniation cases. We investigated the molecular biologic characteristics of primary herniated discs and recurrent discs to see whether the recurrent discs has the similar biological features with primary herniated discs. Methods Primary herniated disc and recurrent disc cells were obtained by discectomy of lumbar disc patients and cells were isolated and then taken through monolayer cultures. We compared chondrogenic and osteogenic mRNA gene expression, and western blot between the two groups. Results The mRNA gene expression of recurrent disc cells were increased 1.47* times for aggrecan, 1.38 times for type I collagen, 2.04 times for type II collagen, 1.22 times for both Sox-9 and osteocalcin, and 1.31 times for alkaline phosphatase, respectively, compared with the primary herniated lumbar disc cells (*indicates p herniated disc cells and recurrent disc cells. Conclusion These results indicate that the recurrent disc cells have similar chondrogenic and osteogenic gene expression compared to primary herniated disc cells. Therefore, we assumed that the regeneration of remaining discs could fill the previous discectomy space and also it could be one of the factors for disc recurrence especially in the molecular biologic field. PMID:20157374

  4. Metrical analysis of disc-condyle relation with different splint treatment positions in patients with TMJ disc displacement

    Directory of Open Access Journals (Sweden)

    Mu-Qing Liu

    Full Text Available Abstract Objective: To evaluate the effect of bite positions characterizing different splint treatments (anterior repositioning and stabilization splints on the disc-condyle relation in patients with TMJ disc displacement with reduction (DDwR, using magnetic resonance imaging (MRI. Material and Methods: 37 patients, with a mean age of 18.8±4.3 years (7 male and 30 females and diagnosed with DDwR based on the RDC/TMD, were recruited. MRI metrical analysis of the spatial changes of the disc/condyle, as well as their relationships, was done in three positions: maximum intercuspation (Position 1, anterior repositioning splint position (Position 2, and stabilization splint position (Position 3. Disc/condyle coordinate measurements and disc condyle angles were determined and compared. Results: In Position 1, the average disc-condyle angle was 53.4° in the 60 joints with DDwR, while it was −13.3° with Position 2 and 30.1° with Position 3. The frequency of successful "disc recapture" with Position 2 was significantly higher (58/60, 96.7% than Position 3 (20/60, 33.3%. In Positions 2 and 3, the condyle moved forward and downward while the disc moved backward. The movements were, however, more remarkable with Position 2. Conclusions: Anterior repositioning of the mandible improves the spatial relationship between the disc and condyle in patients with DDwR. In addition to anterior and inferior movement of the condyle, transitory posterior movement of the disc also occurred.

  5. Method of extruding and packaging a thin sample of reactive material including forming the extrusion die

    International Nuclear Information System (INIS)

    Lewandowski, E.F.; Peterson, L.L.

    1985-01-01

    This invention teaches a method of cutting a narrow slot in an extrusion die with an electrical discharge machine by first drilling spaced holes at the ends of where the slot will be, whereby the oil can flow through the holes and slot to flush the material eroded away as the slot is being cut. The invention further teaches a method of extruding a very thin ribbon of solid highly reactive material such as lithium or sodium through the die in an inert atmosphere of nitrogen, argon or the like as in a glovebox. The invention further teaches a method of stamping out sample discs from the ribbon and of packaging each disc by sandwiching it between two aluminum sheets and cold welding the sheets together along an annular seam beyond the outer periphery of the disc. This provides a sample of high purity reactive material that can have a long shelf life

  6. Clinical outcomes of percutaneous plasma disc coagulation therapy for lumbar herniated disc diseases.

    Science.gov (United States)

    Kim, Sang Hyun; Kim, Sung Chul; Cho, Ki Hong

    2012-01-01

    This is prospective study of clinical outcomes of percutaneous plasma disc coagulation Therapy (PDCT) in patients with herniated lumbar disc disease (HLD) to evaluate the safety and efficacy in its clinical application and usefulness as a reliable alternative to microscopic discectomy. Forty-six patients were enrolled in this study from April 2006 to June 2010. All patients had one-level HLD. Disc degeneration was graded on routine T2-weighted magnetic resonance Image (MRI) using the Pfirrmann's grading system and all index levels were grade 3 and grade 4. Indications for surgery were radiculopathy caused by disc protrusion with soft consistency. MRI was done at one month after the procedure in all patients to check post-PDCT change. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. This study was approved by the Institutional Review Board of our institution. The age of the study population ranged from 16 to 59 years with a mean age of 37.2 years. There were 29 males and 17 females in this study. The mean period of clinical follow-up was 21 months. The average preoperative VAS score for radiculopathy was 7.4±1.4, while the final follow-up VAS score was 1.4±0.7 (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. PDCT is a safe and efficient treatment modality in a selective patient with HLD.

  7. Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s)

    Science.gov (United States)

    Silva Aguirre, V.; Bojsen-Hansen, M.; Slumstrup, D.; Casagrande, L.; Kawata, D.; Ciucǎ, I.; Handberg, R.; Lund, M. N.; Mosumgaard, J. R.; Huber, D.; Johnson, J. A.; Pinsonneault, M. H.; Serenelli, A. M.; Stello, D.; Tayar, J.; Bird, J. C.; Cassisi, S.; Hon, M.; Martig, M.; Nissen, P. E.; Rix, H. W.; Schönrich, R.; Sahlholdt, C.; Trick, W. H.; Yu, J.

    2018-04-01

    Investigations of the origin and evolution of the Milky Way disc have long relied on chemical and kinematic identifications of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted most studies to small samples, normally confined to the solar neighbourhood. Here, we break this impasse with the help of asteroseismic inference and perform a chronology of the evolution of the disc throughout the age of the Galaxy. We chemically dissect the Milky Way disc population using a sample of red giant stars spanning out to 2 kpc in the solar annulus observed by the Kepler satellite, with the added dimension of asteroseismic ages. Our results reveal a clear difference in age between the low- and high-α populations, which also show distinct velocity dispersions in the V and W components. We find no tight correlation between age and metallicity nor [α/Fe] for the high-α disc stars. Our results indicate that this component formed over a period of more than 2 Gyr with a wide range of [M/H] and [α/Fe] independent of time. Our findings show that the kinematic properties of young α-rich stars are consistent with the rest of the high-α population and different from the low-α stars of similar age, rendering support to their origin being old stars that went through a mass transfer or stellar merger event, making them appear younger, instead of migration of truly young stars formed close to the Galactic bar.

  8. Non-axisymmetric line-driven disc winds - I. Disc perturbations

    Science.gov (United States)

    Dyda, Sergei; Proga, Daniel

    2018-04-01

    We study mass outflows driven from accretion discs by radiation pressure due to spectral lines. To investigate non-axisymmetric effects, we use the ATHENA++ code and develop a new module to account for radiation pressure driving. In 2D, our new simulations are consistent with previous 2D axisymmetric solutions by Proga et al., who used the ZEUS 2D code. Specifically, we find that the disc winds are time dependent, characterized by a dense stream confined to ˜45° relative to the disc mid-plane and bounded on the polar side by a less dense, fast stream. In 3D, we introduce a vertical, ϕ-dependent, subsonic velocity perturbation in the disc mid-plane. The perturbation does not change the overall character of the solution but global outflow properties such as the mass, momentum, and kinetic energy fluxes are altered by up to 100 per cent. Non-axisymmetric density structures develop and persist mainly at the base of the wind. They are relatively small, and their densities can be a few times higher than the azimuthal average. The structure of the non-axisymmetric and axisymmetric solutions differ also in other ways. Perhaps most importantly from the observational point of view are the differences in the so-called clumping factors, that serve as a proxy for emissivity due to two body processes. In particular, the spatially averaged clumping factor over the entire fast stream, while it is of a comparable value in both solutions, it varies about 10 times faster in the non-axisymmetric case.

  9. FRB as products of accretion disc funnels

    Science.gov (United States)

    Katz, J. I.

    2017-10-01

    The repeating FRB 121102, the only fast radio burst (FRB) with an accurately determined position, is associated with a variable persistent radio source. I suggest that an FRB originates in the accretion disc funnels of black holes. Narrowly collimated radiation is emitted along the wandering instantaneous angular momentum axis of accreted matter. This emission is observed as a fast radio burst when it sweeps across the direction to the observer. In this model, in contrast to neutron star (pulsar, RRAT or SGR) models, repeating FRBs do not have underlying periodicity and are co-located with persistent radio sources resulting from their off-axis emission. The model is analogous, on smaller spatial, lower mass and accretion rate and shorter temporal scales, to an active galactic nucleus (AGN), with FRB corresponding to blazars in which the jets point towards us. The small inferred black hole masses imply that FRBs are not associated with galactic nuclei.

  10. Magnetic Field Amplification via Protostellar Disc Dynamos

    Science.gov (United States)

    Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Koldoba, A. V.; Wasserman, I.

    2018-03-01

    We numerically investigate the generation of a magnetic field in a protostellar disc via an αΩ-dynamo and the resulting magnetohydrodynamic (MHD) driven outflows. We find that for small values of the dimensionless dynamo parameter αd the poloidal field grows exponentially at a rate σ ∝ Ω _K √{α _d}, before saturating to a value ∝ √{α _d}. The dynamo excites dipole and octupole modes, but quadrupole modes are suppressed, because of the symmetries of the seed field. Initial seed fields too weak to launch MHD outflows are found to grow sufficiently to launch winds with observationally relevant mass fluxes of order 10^{-9} M_{⊙}/{yr} for T Tauri stars. This suggests αΩ-dynamos may be responsible for generating magnetic fields strong enough to launch observed outflows.

  11. Likelihood inference for unions of interacting discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisová, Katarina

    To the best of our knowledge, this is the first paper which discusses likelihood inference or a random set using a germ-grain model, where the individual grains are unobservable edge effects occur, and other complications appear. We consider the case where the grains form a disc process modelled...... is specified with respect to a given marked Poisson model (i.e. a Boolean model). We show how edge effects and other complications can be handled by considering a certain conditional likelihood. Our methodology is illustrated by analyzing Peter Diggle's heather dataset, where we discuss the results...... of simulation-based maximum likelihood inference and the effect of specifying different reference Poisson models....

  12. Multilayer optical disc system using homodyne detection

    Science.gov (United States)

    Kurokawa, Takahiro; Ide, Tatsuro; Tanaka, Yukinobu; Watanabe, Koichi

    2014-09-01

    A write/read system using high-productivity multilayer optical discs was developed. The recording medium used in the system consists of planar recording layers and a separated guide layer, and is fabricated by web coating and lamination process. The recording layers in the medium are made of one-photon-absorption material, on which data can be recorded with a normal laser diode. The developed system is capable of focusing and tracking on the medium and amplifying readout signals by using phase-diversity homodyne detection. A highly layer-selective focusing method using homodyne detection was also proposed. This method obtains stable focus-error signals with clearly separated S-shaped curves even when layer spacing is quite narrow, causing large interlayer crosstalk. Writing on the medium and reading with the signal amplification effect of homodyne detection was demonstrated. In addition, the effectiveness of the method was experimentally evaluated.

  13. The Endcap Disc DIRC of PANDA

    Science.gov (United States)

    Düren, M.; Etzelmüller, E.; Föhl, K.; Hayrapetyan, A.; Kröck, B.; Merle, O.; Rieke, J.; Schmidt, M.; Wasem, T.; Britting, A.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Zühlsdorf, M.; Cowie, E.; Keri, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

    2017-12-01

    The Endcap Disc DIRC (EDD) for PANDA has been designed to identify traversing pions, kaons and protons in the future PANDA experiment. Its central part is a 2 cm thick fused silica plate. Focussing optics are attached to the outer rim of the plate, outside of the acceptance of the experiment. Fast, high-resolution MCP-PMTs, designed to register single Cherenkov photons, have been tested in magnetic field. Filters limit the spectral acceptance of the sensors to reduce dispersion effects and to extend their lifetime. A compact and fast readout is realized with ASICs. Analytical reconstruction algorithms allow for fast particle identification. The angular resolution of a DIRC prototype has been simulated in Monte Carlo and confirmed in a test beam. The final detector will be able to provide a 4 σπ / K separation up to a momentum of 4 GeV / c .

  14. Asthma and early herniated intervertebral disc disease.

    Science.gov (United States)

    Chiu, Cheng-Di; Chen, Hsuan-Ju; Saw, Hean-Pat; Yao, Nai-Wei; Yen, Hung-Rong; Kao, Chia-Hung

    2017-11-01

    The etiology of herniated intervertebral disc (HIVD) disease in children and adolescents is multifactorial and not merely related to disc degeneration. Therefore, in the present study, we investigated the relationship between young asthma patients and the risk of early HIVD disease in a population under 30 years of age. Data from the National Health Insurance Research Database (NHIRD) of Taiwan were used to conduct a retrospective longitudinal cohort study. The study cohort comprised 23,470 patients with asthma (asthma group) and 23,470 patients without asthma (non-asthma group), who were selected through frequency matching on the basis of sex, age, and the index year. The study patients were followed until HIVD disease occurrence, withdrawal from the National Health Insurance program, or 31 December 2013. Cox proportional hazards regression analysis was conducted to assess the risk of HIVD disease in the asthma group after adjustment for sex, age, and comorbidities. After adjustment for sex, age, and comorbidities, the asthma group had a 1.69-fold (95% confidence interval [CI] = 1.29-2.23) higher risk of HIVD disease than did the non-asthma group. In addition, the asthma group had a higher risk of cervical and lumbar HIVD diseases than did the non-asthma group (adjusted hazard ratio [HR] = 2.38; 95% CI = 1.25-4.57 and adjusted HR = 1.56; 95% CI = 1.15-2.12, respectively). Young patients with asthma are at a significantly higher risk of early cervical or lumbar HIVD disease.

  15. Dense Fully Convolutional Segmentation of the Optic Disc and Cup in Colour Fundus for Glaucoma Diagnosis

    Directory of Open Access Journals (Sweden)

    Baidaa Al-Bander

    2018-03-01

    Full Text Available Glaucoma is a group of eye diseases which can cause vision loss by damaging the optic nerve. Early glaucoma detection is key to preventing vision loss yet there is a lack of noticeable early symptoms. Colour fundus photography allows the optic disc (OD to be examined to diagnose glaucoma. Typically, this is done by measuring the vertical cup-to-disc ratio (CDR; however, glaucoma is characterised by thinning of the rim asymmetrically in the inferior-superior-temporal-nasal regions in increasing order. Automatic delineation of the OD features has potential to improve glaucoma management by allowing for this asymmetry to be considered in the measurements. Here, we propose a new deep-learning-based method to segment the OD and optic cup (OC. The core of the proposed method is DenseNet with a fully-convolutional network, whose symmetric U-shaped architecture allows pixel-wise classification. The predicted OD and OC boundaries are then used to estimate the CDR on two axes for glaucoma diagnosis. We assess the proposed method’s performance using a large retinal colour fundus dataset, outperforming state-of-the-art segmentation methods. Furthermore, we generalise our method to segment four fundus datasets from different devices without further training, outperforming the state-of-the-art on two and achieving comparable results on the remaining two.

  16. DIF-1 induces the basal disc of the Dictyostelium fruiting body.

    Science.gov (United States)

    Saito, Tamao; Kato, Atsushi; Kay, Robert R

    2008-05-15

    The polyketide DIF-1 induces Dictyostelium amoebae to form stalk cells in culture. To better define its role in normal development, we examined the phenotype of a mutant blocking the first step of DIF-1 synthesis, which lacks both DIF-1 and its biosynthetic intermediate, dM-DIF-1 (des-methyl-DIF-1). Slugs of this polyketide synthase mutant (stlB(-)) are long and thin and rapidly break up, leaving an immotile prespore mass. They have approximately 30% fewer prestalk cells than their wild-type parent and lack a subset of anterior-like cells, which later form the outer basal disc. This structure is missing from the fruiting body, which perhaps in consequence initiates culmination along the substratum. The lower cup is rudimentary at best and the spore mass, lacking support, slips down the stalk. The dmtA(-) methyltransferase mutant, blocked in the last step of DIF-1 synthesis, resembles the stlB(-) mutant but has delayed tip formation and fewer prestalk-O cells. This difference may be due to accumulation of dM-DIF-1 in the dmtA(-) mutant, since dM-DIF-1 inhibits prestalk-O differentiation. Thus, DIF-1 is required for slug migration and specifies the anterior-like cells forming the basal disc and much of the lower cup; significantly the DIF-1 biosynthetic pathway may supply a second signal - dM-DIF-1.

  17. Thin Film Processes

    CERN Document Server

    Vossen, John L.

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques. Key Features * Provides an all-new sequel to the 1978 classic, Thin Film Processes * Introduces new topics, and several key topics presented in the original volume are updated * Emphasizes practical applications of major thin film deposition and etching processes * Helps readers find the appropriate technology for a particular application

  18. On the vertical-shear instability in astrophysical discs

    Science.gov (United States)

    Barker, A. J.; Latter, H. N.

    2015-06-01

    We explore the linear stability of astrophysical discs exhibiting vertical shear, which arises when there is a radial variation in the temperature or entropy. Such discs are subject to a `vertical-shear instability', which recent non-linear simulations have shown to drive hydrodynamic activity in the MRI-stable regions of protoplanetary discs. We first revisit locally isothermal discs using the quasi-global reduced model derived by Nelson et al. This analysis is then extended to global axisymmetric perturbations in a cylindrical domain. We also derive and study a reduced model describing discs with power-law radial entropy profiles (`locally polytropic discs'), which are somewhat more realistic in that they possess physical (as opposed to numerical) surfaces. The fastest growing modes have very short wavelengths and are localized at the disc surfaces (if present), where the vertical shear is maximal. An additional class of modestly growing vertically global body modes is excited, corresponding to destabilized classical inertial waves (`r modes'). We discuss the properties of both types of modes, and stress that those that grow fastest occur on the shortest available length-scales (determined either by the numerical grid or the physical viscous length). This ill-posedness makes simulations of the instability difficult to interpret. We end with some brief speculation on the non-linear saturation and resulting angular momentum transport.

  19. Spinal canal dimensions affect outcome of adolescent disc herniation.

    Science.gov (United States)

    Linkoaho, O; Kivisaari, R; Ahonen, M

    2017-10-01

    Small spinal canal dimensions play a role in symptomatic adult disc herniation, but its role in adolescent disc herniation has not been investigated with MRI. The goal of this study was to examine retrospectively if there is a correlation with dimensions of osseous spinal canal and need of discectomy in an adolescent population suffering from disc herniation. A retrospective review of child and adolescent patients who were treated in our institution for back or back--related leg pain was conducted. Patients were divided in three groups; group 1: lumbar disc herniation requiring operative treatment; group 2: lumbar disc herniation treated with observation; and group 3: back pain and no disc herniation on MRI. MRI images and radiographs were studied for spinal canal dimensions and compared between groups. The discectomy group presented considerably smaller spinal canal dimensions measured from the MRI images than the two other groups. Adolescent patients requiring operative treatment for symptomatic disc herniation have smaller osseous spinal canals than patients who are managed non-operatively.

  20. Percutaneous treatment of cervical and lumbar herniated disc.

    Science.gov (United States)

    Kelekis, A; Filippiadis, D K

    2015-05-01

    Therapeutic armamentarium for symptomatic intervertebral disc herniation includes conservative therapy, epidural infiltrations (interlaminar or trans-foraminal), percutaneous therapeutic techniques and surgical options. Percutaneous, therapeutic techniques are imaging-guided, minimally invasive treatments for intervertebral disc herniation which can be performed as outpatient procedures. They can be classified in 4 main categories: mechanical, thermal, chemical decompression and biomaterials implantation. Strict sterility measures are a prerequisite and should include extensive local sterility and antibiotic prophylaxis. Indications include the presence of a symptomatic, small to medium sized contained intervertebral disc herniation non-responding to a 4-6 weeks course of conservative therapy. Contraindications include sequestration, infection, segmental instability (spondylolisthesis), uncorrected coagulopathy or a patient unwilling to provide informed consent. Decompression techniques are feasible and reproducible, efficient (75-94% success rate) and safe (>0.5% mean complications rate) therapies for the treatment of symptomatic intervertebral disc herniation. Percutaneous, imaging guided, intervertebral disc therapeutic techniques can be proposed either as an initial treatment or as an attractive alternative prior to surgery for the therapy of symptomatic herniation in both cervical and lumbar spine. This article will describe the mechanism of action for different therapeutic techniques applied to intervertebral discs of cervical and lumbar spine, summarize the data concerning safety and effectiveness of these treatments, and provide a rational approach for the therapy of symptomatic intervertebral disc herniation in cervical and lumbar spine. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  1. Percutaneous treatment of cervical and lumbar herniated disc

    Energy Technology Data Exchange (ETDEWEB)

    Kelekis, A., E-mail: akelekis@med.uoa.gr; Filippiadis, D.K., E-mail: dfilippiadis@yahoo.gr

    2015-05-15

    Therapeutic armamentarium for symptomatic intervertebral disc herniation includes conservative therapy, epidural infiltrations (interlaminar or trans-foraminal), percutaneous therapeutic techniques and surgical options. Percutaneous, therapeutic techniques are imaging-guided, minimally invasive treatments for intervertebral disc herniation which can be performed as outpatient procedures. They can be classified in 4 main categories: mechanical, thermal, chemical decompression and biomaterials implantation. Strict sterility measures are a prerequisite and should include extensive local sterility and antibiotic prophylaxis. Indications include the presence of a symptomatic, small to medium sized contained intervertebral disc herniation non-responding to a 4–6 weeks course of conservative therapy. Contraindications include sequestration, infection, segmental instability (spondylolisthesis), uncorrected coagulopathy or a patient unwilling to provide informed consent. Decompression techniques are feasible and reproducible, efficient (75–94% success rate) and safe (>0.5% mean complications rate) therapies for the treatment of symptomatic intervertebral disc herniation. Percutaneous, imaging guided, intervertebral disc therapeutic techniques can be proposed either as an initial treatment or as an attractive alternative prior to surgery for the therapy of symptomatic herniation in both cervical and lumbar spine. This article will describe the mechanism of action for different therapeutic techniques applied to intervertebral discs of cervical and lumbar spine, summarize the data concerning safety and effectiveness of these treatments, and provide a rational approach for the therapy of symptomatic intervertebral disc herniation in cervical and lumbar spine.

  2. MHD simulations of ram pressure stripping of a disc galaxy

    Science.gov (United States)

    Ramos-Martínez, Mariana; Gómez, Gilberto C.; Pérez-Villegas, Ángeles

    2018-05-01

    The removal of the interstellar medium (ISM) of disc galaxies through ram pressure stripping (RPS) has been extensively studied in numerous simulations. Nevertheless, the role of magnetic fields (MFs) on the gas dynamics in this process has been hardly studied, although the MF influence on the large-scale disc structure is well established. With this in mind, we present a 3D magnetohydrodynamic simulation of face-on RPS of a disc galaxy to study the impact of the galactic MF in the gas stripping. The main effect of including a galactic MF is a flared disc. When the intracluster medium wind hits this flared disc, oblique shocks are produced at the interaction interface, where the ISM is compressed, generating a gas inflow from large radii towards the central regions of the galaxy. This inflow is observed for {˜ } 150 {Myr} and may supply the central parts of the galaxy with material for star formation while the outskirts of the disc are being stripped of gas, thus the oblique shocks can induce and enhance the star formation in the remaining disc. We also observed that the MF alters the shape and structure of the swept gas, giving a smooth appearance in the magnetized case and clumpier and filamentary-like morphology in the hydro case. Finally, we estimated the truncation radius expected for our models using the Gunn-Gott criterion and found that that is in agreement with the simulations.

  3. Comparison of Heidelberg Retina Tomograph with disc-macula distance to disc diameter ratio in diagnosing optic nerve hypoplasia.

    Science.gov (United States)

    Pang, Yi; Frantz, Kelly A

    2016-05-01

    To evaluate whether Heidelberg Retinal Tomograph (HRT) is a valid test for diagnosing congenital optic nerve hypoplasia (CONH) compared to the ratio of the distance between the centre of the optic disc and the centre of the macula and the mean optic disc diameter (DM:DD ratio). Furthermore, to determine the optimal cut-off value of HRT disc area to differentiate a hypoplastic disc from a normal optic disc. A total of 33 subjects with CONH (4-67 years old) and 160 normal subjects (5-65 years old) were recruited and underwent comprehensive eye examinations, fundus photography and HRT. Receiver operating characteristic curves for DM:DD ratio and HRT disc area were constructed based on data from the 46 CONH eyes and 160 control eyes. Mean (±S.D.) HRT disc area was 1.94 (±0.54) mm(2) for the control eyes and 0.84 (±0.35) mm(2) for the CONH eyes (p < 0.0001). The area under the curve (AUC) for DM:DD ratio was 0.83 (95% confidence interval: 0.76-0.90). The AUC for HRT disc area was 0.96 (95% confidence interval: 0.94-0.99). A statistically significant difference was found between AUC for HRT disc area and that for DM:DD ratio (p = 0.0004). The optimal cut-off value for HRT disc area was 1.42 mm(2) with 95% sensitivity and 85% specificity. The optimal cut-off value for DM:DD ratio was 3.20 with 78% sensitivity and 78% specificity. Both HRT and the DM:DD ratio are valid tests to aid diagnosis of CONH. HRT is superior to DM:DD ratio in diagnosing CONH with higher sensitivity and specificity. We suggest the optimal cut-off value for HRT disc area as 1.42 mm(2) in order to discriminate a hypoplastic disc from a normal optic disc. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  4. Fundamental study on articular disc with magnetic resonance imagings

    International Nuclear Information System (INIS)

    Chiba, Toyokazu

    1993-01-01

    In order to establish criteria of reading MRI of the temporomandibular joint, a morphological comparison between MRI and the section, and an observation of the articular disc associated with the opening were made. Five temporomandibular joints isolated from 3 human cadavers were subjected to MRI, and sections were prepared to examine criteria of reading MRI. In 20 male adults, 40 temporomandibular joints underwent MRI in three conditions of the intercuspal position, 10 and 20 mm opening positions, and the kinetics of the articular disc were examined. External feature of the head of mandible and that of the articular fossa, the articular tubercule and the postglenoid process were outlined in a row of blacks. The articular disc was outlined in a row of dark ashen areas of the anterior band, the intermediate region, and the posterior band. In the intercuspal position, the head of mandible was rarely covered with the articular disc, and being situated postero-inferiorly, at the most rear point of the posterior band of the articular disc. In the 10 mm-opening position, the head of mandible was practically covered with the articular disc. In the 20 mm-opening position, the intermediate region of the articular disc, and the head of mandible were situated in an approximate position. Quantitative movement of the articular disc was slower than that of the head of mandible. Comparison of various points of the articular disc revealed that movements of the anterior and posterior band varied almost proportionally to the opening distance, but with lesser movement of the intermediate region. (author)

  5. Floppy disc units for data collection from neutron beam experiments

    International Nuclear Information System (INIS)

    Hall, J.W.

    1976-02-01

    The replacement of paper tape output facilities on neutron beam equipment on DIDO and PLUTO reactors by floppy discs will improve reliability and provide a more manageable data storage medium. The cost of floppy disc drives is about the same as a tape punch and printer and less than other devices such as a magnetic tape. Suitable floppy disc controllers are not at present available and a unit was designed as a directly pluggable replacement for paper tape punches. This design was taken as the basis in the development of a prototype unit for use in neutron beam equipment. The circuit operation for this prototype unit is described. (author)

  6. Bilateral macular colobomata: Temporal dragging of optic disc

    Directory of Open Access Journals (Sweden)

    David J Mathew

    2015-01-01

    Full Text Available A 13-year-old male presented with decreased vision and squint from childhood. He had bilateral large colobomata at the macula in each eye, the one on the right being larger than the left. The disc was dragged temporally with straightening of the temporal retinal vessels. This is a case report of bilateral large macular coloboma and serves to report its association with a temporally dragged disc and straightened temporal retinal vessels. A dragged disc if present with a colobomatous defect at the macula may strengthen the case for diagnosis of macular coloboma and help exclude other differentials.

  7. Animal models of disc degeneration and major genetic strategies.

    Science.gov (United States)

    Sun, Fu; Qu, Ji-Ning; Zhang, Yin-Gang

    2013-01-01

    The establishment of a reliable animal model of lumbar disc degeneration (AMDD) is important for studying pathogenesis and evaluating treatment effectiveness. However, an ideal AMDD for use in laboratory studies has not yet been produced. This retrospective study reviews and compares several common AMDD and discusses their strengths and weaknesses. We also suggest a new method for establishing future AMDD. The identified genes associated with disc degeneration are susceptibility genes, which elevate risk but do not necessarily lead to disease occurrence. We propose to identify families with hereditary disc degeneration, find major casual genes with exome sequencing, and establish transgenic animal models. This approach may help us to build an improved AMDD.

  8. Comparison of efficacy of three commercially available antibiotic discs

    Directory of Open Access Journals (Sweden)

    Joshi A

    2008-01-01

    Full Text Available A study was undertaken to evaluate the efficacy of commercially available antimicrobial discs manufactured by Oxoid, UK, HiMedia Laboratories, Mumbai and Span Diagnostics, Surat. The discs were evaluated for their performance on the basis of percentage of coefficient of variation (%CV which is a measure of reproducibility, mean zone diameters which is a measure of accuracy and range of zone diameter using both standard ATCC strains and clinical isolates. The data showed variation for all three manufacturers and therefore routine and regular quality control of discs as well as meticulous following of good laboratory practices is strongly advocated in clinical laboratories

  9. Bilateral macular colobomata: Temporal dragging of optic disc.

    Science.gov (United States)

    Mathew, David J

    2015-04-01

    A 13-year-old male presented with decreased vision and squint from childhood. He had bilateral large colobomata at the macula in each eye, the one on the right being larger than the left. The disc was dragged temporally with straightening of the temporal retinal vessels. This is a case report of bilateral large macular coloboma and serves to report its association with a temporally dragged disc and straightened temporal retinal vessels. A dragged disc if present with a colobomatous defect at the macula may strengthen the case for diagnosis of macular coloboma and help exclude other differentials.

  10. Operative management of lumbar disc herniation : the evolution of knowledge and surgical techniques in the last century.

    Science.gov (United States)

    Postacchini, F; Postacchini, R

    2011-01-01

    Removal of a herniated disc with the use of the operative microscope was first performed by Yasargil (Adv Neurosurg. 4:81-2, 1977) in 1977. However, it began to be used more and more only in the late 1980s (McCulloch JA (1989) Principles of microsurgery for lumbar disc disease. Raven Press, New York). In the 1990s, many spinal surgeons abandoned conventional discectomy with naked-eye to pass to the routine practice of microdiscectomy. The merits of this technique are that it allows every type of disc herniation to be excised through a short approach to skin, fascia and muscles as well as a limited laminoarthrectomy. For these reasons, it has been, and still is, considered the "gold standard" of surgical treatment for lumbar disc herniation, and the method used by the vast majority of spinal surgeons. In the 1990s, the advent of MRI and the progressive increase in definition of this modality of imaging, as well as histopathologic and immunochemical studies of disc tissue and the analysis of the results of conservative treatments have considerably contributed to the knowledge of the natural evolution of a herniated disc. It was shown that disc herniation may decrease in size or disappear in a few weeks or months. Since the second half of the 1990s there has been a revival of percutaneous procedures. Some of these are similar to the percutaneous automated nucleotomy; other methods are represented by intradiscal injection of a mixture of "oxygen-ozone" (Alexandre A, Buric J, Paradiso R. et al. (2001) Intradiscal injection of oxygen ozone for the treatment of lumbar disc herniations: result at 5 years. 12th World Congress of Neurosurgery; 284-7), or laserdiscectomy performed under CT scan (Menchetti PPM. (2006) Laser Med Sci. 4:25-7). The really emerging procedure is that using an endoscope inserted into the disc through the intervertebral foramen to visualize the herniation and remove it manually using thin pituitary rongeurs, a radiofrequency probe or both (Chiu JC

  11. The probability of spontaneous regression of lumbar herniated disc: a systematic review.

    Science.gov (United States)

    Chiu, Chun-Chieh; Chuang, Tai-Yuan; Chang, Kwang-Hwa; Wu, Chien-Hua; Lin, Po-Wei; Hsu, Wen-Yen

    2015-02-01

    To determine the probability of spontaneous disc regression among each type of lumbar herniated disc, using a systematic review. Medline, Cochrane Library, CINAHL, and Web of Science were searched using key words for relevant original articles published before March 2014. Articles were limited to those published in English and human studies. Articles had to: (1) include patients with lumbar disc herniation treated conservatively; (2) have at least two imaging evaluations of the lumbar spine; and (3) exclude patients with prior lumbar surgery, spinal infections, tumors, spondylolisthesis, or spinal stenosis. Two reviewers independently extracted study details and findings. Thirty-one studies met the inclusion criteria. Furthermore, if the classification of herniation matched the recommended classification of the combined Task Forces, the data were used for combined analysis of the probability of disc regression of each type. Nine studies were applicable for probability calculation. The rate of spontaneous regression was found to be 96% for disc sequestration, 70% for disc extrusion, 41% for disc protrusion, and 13% for disc bulging. The rate of complete resolution of disc herniation was 43% for sequestrated discs and 15% for extruded discs. Spontaneous regression of herniated disc tissue can occur, and can completely resolve after conservative treatment. Patients with disc extrusion and sequestration had a significantly higher possibility of having spontaneous regression than did those with bulging or protruding discs. Disc sequestration had a significantly higher rate of complete regression than did disc extrusion. © The Author(s) 2014.

  12. 26 CFR 1.1014-9 - Special rule with respect to DISC stock.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 11 2010-04-01 2010-04-01 true Special rule with respect to DISC stock. 1.1014... respect to DISC stock. (a) In general. If property consisting of stock of a DISC or former DISC (as... distributions with respect to the stock which may have been made, after the date of the decedent's death and on...

  13. Lumbar disc degeneration is an equally important risk factor as lumbar fusion for causing adjacent segment disc disease.

    Science.gov (United States)

    Natarajan, Raghu N; Andersson, Gunnar B J

    2017-01-01

    Treatment of degenerative spinal disorders by fusion produces abnormal mechanical conditions at mobile segments above or below the site of spinal disorders and is clinically referred to as adjacent segments disc disease (ASDD) or transition syndrome in the case of a previous surgical treatment. The aim of the current study is to understand with the help of poro-elastic finite element models how single or two level degeneration of lower lumbar levels influences motions at adjacent levels and compare the findings to motions produced by single or two level fusions when the adjacent disk has varying degree of degeneration. Validated grade-specific finite element models including varying grades of disc degeneration at lower lumbar levels with and without fusion were developed and used to determine motions at all levels of the lumbar spine due to applied moment loads. Results showed that adjacent disc motions do depend on severity of disc degeneration, number of disc degenerated or fused, and level at which degeneration or fusion occurred. Furthermore, single level degeneration and single level fusion produced similar amount of adjacent disc motions. The pattern of increase in adjacent segment motions due to disc degeneration and increase in motions at segment adjacent to fusion was similar. Based on the current study, it can be concluded that disc degeneration should also be considered as a risk factor in addition to fusion for generating adjacent disc degeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:123-130, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  14. Thin films on cantilevers

    NARCIS (Netherlands)

    Nazeer, H.

    2012-01-01

    The main goal of the work compiled in this thesis is to investigate thin films for integration in micro electromechanical systems (MEMS). The miniaturization of MEMS actuators and sensors without compromising their performance requires thin films of different active materials with specific

  15. Spinal Neurofibroma Masquerading as a Herniated Disc: A case report.

    Science.gov (United States)

    Lamki, Tariq; Ammirati, Mario

    2012-11-01

    We present the only case in English medical literature of a spinal neurofibroma misdiagnosed as a herniated disc using magnetic resonance imaging (MRI). This case presented with typical symptoms and radiological findings of a herniated disc. Intraoperatively, an abnormality was noted at the S1 nerve root sleeve. Further exploration revealed a spinal neurofibroma which was completely resected, resulting in an improvement in the patient's symptoms. Currently, there is heavy reliance on MRI as a highly sensitive and specific tool used in the diagnosis of herniated lumbar discs. Although there have been occasional reports of misdiagnoses using MRI, there are no reported cases of a spinal neurofibroma being misdiagnosed as a herniated lumbar disc. Despite great advances in radiological diagnostic imaging, surgical surprises do still occur. Ultimately, instinct is still essential in intraoperative surgical decisions.

  16. Adjacent Lumbar Disc Herniation after Lumbar Short Spinal Fusion

    Directory of Open Access Journals (Sweden)

    Koshi Ninomiya

    2014-01-01

    Full Text Available A 70-year-old outpatient presented with a chief complaint of sudden left leg motor weakness and sensory disturbance. He had undergone L4/5 posterior interbody fusion with L3–5 posterior fusions for spondylolisthesis 3 years prior, and the screws were removed 1 year later. He has been followed up for 3 years, and there had been no adjacent segment problems before this presentation. Lumbar magnetic resonance imaging (MRI showed a large L2/3 disc hernia descending to the L3/4 level. Compared to the initial MRI, this hernia occurred in an “intact” disc among multilevel severely degenerated discs. Right leg paresis and bladder dysfunction appeared a few days after admission. Microscopic lumbar disc herniotomy was performed. The right leg motor weakness improved just after the operation, but the moderate left leg motor weakness and difficulty in urination persisted.

  17. Crova's Disc: A Way to Make Sound Waves "Visible."

    Science.gov (United States)

    Hastings, R. B.

    1981-01-01

    Explained are the differences between and offered are examples of longitudinal and transverse sound waves. Described is the construction of the Crova's Disc, a device used in the teaching of the propagation and properties of sound waves. (DS)

  18. Computerized phased array UT system for turbine disc rim inspection

    International Nuclear Information System (INIS)

    Goto, M.; Ohmatsu, K.; Nagai, S.; Komura, I.

    1988-01-01

    Turbine disc rim cracking in the nuclear power plants has been a major reliability issue in recent years. This problem has led to increased interest in periodic nondestructive examination and the computerized inspection system using phased array probe called PADRIS (phased array disc rim inspection system) has been developed. It provides for rapid assessment of disk rim integrity without removing blades from the disc rim during a brief unit shutdown and in highly confined spaces. PADRIS has performed successfully during recent field trials at the nuclear power plants, and both the rapid inspection and the precise evaluation capability for the disc rim cracking was established. This paper summarizes the outline of the PADRIS system and the results of the field trial

  19. A truly Newtonian softening length for disc simulations

    Czech Academy of Sciences Publication Activity Database

    Huré, J.-M.; Trova, Audrey

    2015-01-01

    Roč. 447, č. 2 (2015), s. 1866-1872 ISSN 0035-8711 Institutional support: RVO:67985815 Keywords : accretion discs * gravitation * numerical methods Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.952, year: 2015

  20. A truly Newtonian softening length for disc simulations

    Science.gov (United States)

    Huré, J.-M.; Trova, A.

    2015-02-01

    The softened point mass model is commonly used in simulations of gaseous discs including self-gravity while the value of associated length λ remains, to some degree, controversial. This `parameter' is however fully constrained when, in a discretized disc, all fluid cells are demanded to obey Newton's law. We examine the topology of solutions in this context, focusing on cylindrical cells more or less vertically elongated. We find that not only the nominal length depends critically on the cell's shape (curvature, radial extension, height), but it is either a real or an imaginary number. Setting λ as a fraction of the local disc thickness - as usually done - is indeed not the optimal choice. We then propose a novel prescription valid irrespective of the disc properties and grid spacings. The benefit, which amounts to 2-3 more digits typically, is illustrated in a few concrete cases. A detailed mathematical analysis is in progress.

  1. The disc contribution to rotation curves of spiral galaxies

    International Nuclear Information System (INIS)

    Persic, M.; Salucci, P.

    1990-01-01

    We formulate analytically the maximum disc hypothesis (MDH) in the framework of a disc/halo mass decomposition, and apply it to a sample of suitably selected optical rotation curves. We find that the resulting disc-to-total mass ratios show a definite trend of increasing dark-to-luminous mass ratio with decreasing luminosity, in very good agreement with our previous results obtained by means of different decomposition techniques. The same trend is also clearly discernible when the mass ratios (at the same radius in disc length-scale units) obtained from published MDH models are correlated with luminosity. We discuss possible reasons why previous studies which have assumed a similar framework have missed this fundamental systematics of dark matter. (author)

  2. Thermal/Mechanical Measurement and Modeling of Bicycle Disc Brakes

    Directory of Open Access Journals (Sweden)

    Ioan Feier

    2018-02-01

    Full Text Available Brake induced heating has become more difficult to control as bicycle component mass has been reduced. High-power braking with insufficient cooling or thermal capacitance can create excessive temperatures, boiling brake fluid, performance degradation, and damage. To better understand component heating, a disc braking dynamometer has been constructed with a motor driven disc, hydraulic braking, and a miniature wind tunnel. Disc temperatures are studied for various braking scenarios using infrared techniques and thermocouples. A transient, numerical, MATLAB, lumped parameter thermal/mechanical model is created to predict the impact of key design parameters on braking performance and to understand the heat loss mechanisms from the brake system components. Computational fluid dynamics (CFD simulations are used to estimate the disc surface convective cooling coefficients for the model. The final model provides transient temperature predictions based on bicycle velocity and braking power, and successfully matches dynamometer experimental data.

  3. Compact binary merger and kilonova: outflows from remnant disc

    Science.gov (United States)

    Yi, Tuan; Gu, Wei-Min; Liu, Tong; Kumar, Rajiv; Mu, Hui-Jun; Song, Cui-Ying

    2018-05-01

    Outflows launched from a remnant disc of compact binary merger may have essential contribution to the kilonova emission. Numerical calculations are conducted in this work to study the structure of accretion flows and outflows. By the incorporation of limited-energy advection in the hyper-accretion discs, outflows occur naturally from accretion flows due to imbalance between the viscous heating and the sum of the advective and radiative cooling. Following this spirit, we revisit the properties of the merger outflow ejecta. Our results show that around 10-3 ˜ 10-1 M⊙ of the disc mass can be launched as powerful outflows. The amount of unbound mass varies with the disc mass and the viscosity. The outflow-contributed peak luminosity is around 1040 ˜ 1041 erg s-1. Such a scenario can account for the observed kilonovae associated with short gamma-ray bursts, including the recent event AT2017gfo (GW170817).

  4. Goddard Earth Sciences Data and Information Services Center (GES DISC)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) is the home (archive) of Precipitation, Atmospheric Chemistry and Dynamics, and...

  5. Adjacent Lumbar Disc Herniation after Lumbar Short Spinal Fusion

    Science.gov (United States)

    Iwatsuki, Koichi; Ohnishi, Yu-ichiro; Yoshimine, Toshiki

    2014-01-01

    A 70-year-old outpatient presented with a chief complaint of sudden left leg motor weakness and sensory disturbance. He had undergone L4/5 posterior interbody fusion with L3–5 posterior fusions for spondylolisthesis 3 years prior, and the screws were removed 1 year later. He has been followed up for 3 years, and there had been no adjacent segment problems before this presentation. Lumbar magnetic resonance imaging (MRI) showed a large L2/3 disc hernia descending to the L3/4 level. Compared to the initial MRI, this hernia occurred in an “intact” disc among multilevel severely degenerated discs. Right leg paresis and bladder dysfunction appeared a few days after admission. Microscopic lumbar disc herniotomy was performed. The right leg motor weakness improved just after the operation, but the moderate left leg motor weakness and difficulty in urination persisted. PMID:25276453

  6. [Endovascular repair of iliocaval arteriovenous fistula complicating lumbar disc surgery].

    Science.gov (United States)

    Ben Jemaa, H; Maalej, A; Lazzez, K; Jemal, H; Karray, S; Ben Mahfoudh, K

    2016-05-01

    Vascular complications of lumbar disc surgery are rare. Few cases have been reported. Arteriovenous fistulas are the most common. They are due to anatomical relationships between the last lumbar vertebrae, the corresponding discs, and the iliac vessels; degenerative lesions of the intervertebral discs facilitate instrumental vessel perforation, and operative difficulty. Computed tomography is particularly accurate for making the diagnosis. Treatment strategies consist in surgery or endovascular management. Percutaneous endovascular treatment using a stent-graft is a reasonable option for treating arteriovenous fistula. We describe the case of a 50-year-old patient who developed an iliocaval arteriovenous fistula following lumbar disc hernia surgery. The lesion was excluded by a stent-graft. The postoperative period was uneventful. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  7. Transient events in bright debris discs: Collisional avalanches revisited

    Science.gov (United States)

    Thebault, P.; Kral, Q.

    2018-01-01

    Context. A collisional avalanche is set off by the breakup of a large planetesimal, releasing vast amounts of small unbound grains that enter a debris disc located further away from the star, triggering there a collisional chain reaction that could potentially create detectable transient structures. Aims: We investigate this mechanism, using for the first time a fully self-consistent code coupling dynamical and collisional evolutions. We also quantify for the first time the photometric evolution of the system and investigate whether or not avalanches could explain the short-term luminosity variations recently observed in some extremely bright debris discs. Methods: We use the state-of-the-art LIDT-DD code. We consider an avalanche-favoring A6V star, and two set-ups: a "cold disc" case, with a dust release at 10 au and an outer disc extending from 50 to 120 au, and a "warm disc" case with the release at 1 au and a 5-12 au outer disc. We explore, in addition, two key parameters: the density (parameterized by its optical depth τ) of the main outer disc and the amount of dust released by the initial breakup. Results: We find that avalanches could leave detectable structures on resolved images, for both "cold" and "warm" disc cases, in discs with τ of a few 10-3, provided that large dust masses (≳1020-5 × 1022 g) are initially released. The integrated photometric excess due to an avalanche is relatively limited, less than 10% for these released dust masses, peaking in the λ 10-20 μm domain and becoming insignificant beyond 40-50 μm. Contrary to earlier studies, we do not obtain stronger avalanches when increasing τ to higher values. Likewise, we do not observe a significant luminosity deficit, as compared to the pre-avalanche level, after the passage of the avalanche. These two results concur to make avalanches an unlikely explanation for the sharp luminosity drops observed in some extremely bright debris discs. The ideal configuration for observing an

  8. Optical thin film devices

    Science.gov (United States)

    Mao, Shuzheng

    1991-11-01

    Thin film devices are applied to almost all modern scientific instruments, and these devices, especially optical thin film devices, play an essential role in the performances of the instruments, therefore, they are attracting more and more attention. Now there are numerous kinds of thin film devices and their applications are very diversified. The 300-page book, 'Thin Film Device and Applications,' by Prof. K. L. Chopra gives some general ideas, and my paper also outlines the designs, fabrication, and applications of some optical thin film devices made in my laboratory. Optical thin film devices have been greatly developed in the recent decades. Prof. A. Thelan has given a number of papers on the theory and techniques, Prof. H. A. Macleod's book, 'Thin Film Optical Filters,' has concisely concluded the important concepts of optical thin film devices, and Prof. J. A. Dobrowobski has proposed many successful designs for optical thin film devices. Recently, fully-automatic plants make it easier to produce thin film devices with various spectrum requirements, and some companies, such as Balzers, Leybold AG, Satis Vacuum AG, etc., have manufactured such kinds of coating plants for research or mass-production, and the successful example is the production of multilayer antireflection coatings with high stability and reproducibility. Therefore, it could be said that the design of optical thin film devices and coating plants is quite mature. However, we cannot expect that every problem has been solved, the R&D work still continues, the competition still continues, and new design concepts, new techniques, and new film materials are continually developed. Meanwhile, the high-price of fully-automatic coating plants makes unpopular, and automatic design of coating stacks is only the technique for optimizing the manual design according to the physical concepts and experience, in addition, not only the optical system, but also working environment should be taken into account when

  9. The gravo-magneto disc instability with a viscous dead zone

    OpenAIRE

    Martin, Rebecca G.; Lubow, Stephen H.

    2013-01-01

    We consider the evolution of accretion discs that contain some turbulence within a disc dead zone, a region about the disc midplane of a disc that is not sufficiently ionised for the magneto-rotational instability (MRI) to drive turbulence. In particular, we determine whether additional sources of turbulence within a dead zone are capable of suppressing gravo-magneto (GM) disc outbursts that arise from a rapid transition from gravitationally produced to MRI produced turbulence. With viscous $...

  10. Simulation of biological therapies for degenerated intervertebral discs.

    Science.gov (United States)

    Zhu, Qiaoqiao; Gao, Xin; Temple, H Thomas; Brown, Mark D; Gu, Weiyong

    2016-04-01

    The efficacy of biological therapies on intervertebral disc repair was quantitatively studied using a three-dimensional finite element model based on a cell-activity coupled multiphasic mixture theory. In this model, cell metabolism and matrix synthesis and degradation were considered. Three types of biological therapies-increasing the cell density (Case I), increasing the glycosaminoglycan (GAG) synthesis rate (Case II), and decreasing the GAG degradation rate (Case III)-to the nucleus pulposus (NP) of each of two degenerated discs [one mildly degenerated (e.g., 80% viable cells in the NP) and one severely degenerated (e.g., 30% viable cells in the NP)] were simulated. Degenerated discs without treatment were also simulated as a control. The cell number needed, nutrition level demanded, time required for the repair, and the long-term outcomes of these therapies were analyzed. For Case I, the repair process was predicted to be dependent on the cell density implanted and the nutrition level at disc boundaries. With sufficient nutrition supply, this method was predicted to be effective for treating both mildly and severely degenerated discs. For Case II, the therapy was predicted to be effective for repairing the mildly degenerated disc, but not for the severely degenerated disc. Similar results were predicted for Case III. No change in cell density for Cases II and III were predicted under normal nutrition level. This study provides a quantitative guide for choosing proper strategies of biological therapies for different degenerated discs. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  11. Leaf Disc Regeneration of Passion Fruit | Amugune | African Crop ...

    African Journals Online (AJOL)

    A leaf disc regeneration system was developed for passion fruit, Passiflora edulis Sims. Leaf discs were cultured on a modified MS medium containing 8.90 µM BAP or on 8.90 µM BAP and 2.32 µM KIN. Shoots appeared within four weeks. These could be rooted when transferred to the same medium containing 0.54, 2.69 ...

  12. Origin of chemically distinct discs in the Auriga cosmological simulations

    Science.gov (United States)

    Grand, Robert J. J.; Bustamante, Sebastián; Gómez, Facundo A.; Kawata, Daisuke; Marinacci, Federico; Pakmor, Rüdiger; Rix, Hans-Walter; Simpson, Christine M.; Sparre, Martin; Springel, Volker

    2018-03-01

    The stellar disc of the Milky Way shows complex spatial and abundance structure that is central to understanding the key physical mechanisms responsible for shaping our Galaxy. In this study, we use six very high resolution cosmological zoom-in simulations of Milky Way-sized haloes to study the prevalence and formation of chemically distinct disc components. We find that our simulations develop a clearly bimodal distribution in the [α/Fe]-[Fe/H] plane. We find two main pathways to creating this dichotomy, which operate in different regions of the galaxies: (a) an early (z > 1) and intense high-[α/Fe] star formation phase in the inner region (R ≲ 5 kpc) induced by gas-rich mergers, followed by more quiescent low-[α/Fe] star formation; and (b) an early phase of high-[α/Fe] star formation in the outer disc followed by a shrinking of the gas disc owing to a temporarily lowered gas accretion rate, after which disc growth resumes. In process (b), a double-peaked star formation history around the time and radius of disc shrinking accentuates the dichotomy. If the early star formation phase is prolonged (rather than short and intense), chemical evolution proceeds as per process (a) in the inner region, but the dichotomy is less clear. In the outer region, the dichotomy is only evident if the first intense phase of star formation covers a large enough radial range before disc shrinking occurs; otherwise, the outer disc consists of only low-[α/Fe] sequence stars. We discuss the implication that both processes occurred in the Milky Way.

  13. Iliac artery pseudoaneurysm after lumbar disc hernia operation

    Directory of Open Access Journals (Sweden)

    Mehmet Atay

    2016-03-01

    Full Text Available Lumbar disc herniation surgery is usually performed through a posterior approach. Vascular injuries can be counted among the complications. 39 years old male patient had lower extremity pain which has started after lumbar disc herniation surgery and continued for a month. Iliac arterial pseudoaneurysm has been detected in computerized tomography. It was successfully treated with vascular surgery [Cukurova Med J 2016; 41(0.100: 5-7

  14. The diagnostic utility of resistive MRI for lumbar disc hernias

    International Nuclear Information System (INIS)

    Sakaida, Hiroshi; Hanakita, Junya; Suwa, Hideyuki; Nishihara, Kiyoshi; Nishi, Shogo; Ohta, Fumito; Iihara, Kouji

    1990-01-01

    The diagnostic utility of the 0.1 tesla resistive magnetic resonance imaging (MRI) system was studied for 78 lumbar disc hernias in surgically treated 70 patients. Myelographic appearance of the lumbar disc hernias fell into the following three categories: (1) medial type, compressing the thecal sac; (2) mediolateral type, compressing both the nerve root and thecal sac; and (3) lateral type, compressing the nerve root. MRI was performed in low-flip angle (LF) and saturation-recovery (SR) radiofrequency-pulse sequences for the midline and paramedian sagittal sections, respectively. A transverse section was found positive when the laterality of the disc hermia was obtained. A coronal section was found positive when high-intensity disc material compresisng the nerve root was recognized. Diagnostic capability of MRI was graded in three scores: Excellent- the optimal information was provided; Fair- some pieces of information was obtained, but not enough for diagnosis; Poor- the information was not helpful for diagnosis in deciding the operative procedure. Of 13 medial disc hernias, 84.6% was positive in the sagittal plane and 88.9% in the transverse plane. MRI was superior to myelography in 9 lesions. Of 38 mediolateral disc hernias, 84.2% were positive in the sagittal plane, 74.2% in the transverse plane, and 26.7% in the coronal plane. MRI was judged as excellent for 17 lesions, fair for 15 lesions, and poor for 6 lesions. Of 27 lateral disc hernias, 55.6% were positive in the sagittal plane, 50.0% in the transverse plane, and 30.0% in the coronal plane. MRI was judged as excellent for 4 lesions, fair for 11 lesions, and poor for 12 lesions. Resistive MRI system was of limited value in diagnosing surgical indication of lateral lumbar disc hernias, especially for small but painful lesions. (N.K.)

  15. The use of genetic algorithms to model protoplanetary discs

    Science.gov (United States)

    Hetem, Annibal; Gregorio-Hetem, Jane

    2007-12-01

    The protoplanetary discs of T Tauri and Herbig Ae/Be stars have previously been studied using geometric disc models to fit their spectral energy distribution (SED). The simulations provide a means to reproduce the signatures of various circumstellar structures, which are related to different levels of infrared excess. With the aim of improving our previous model, which assumed a simple flat-disc configuration, we adopt here a reprocessing flared-disc model that assumes hydrostatic, radiative equilibrium. We have developed a method to optimize the parameter estimation based on genetic algorithms (GAs). This paper describes the implementation of the new code, which has been applied to Herbig stars from the Pico dos Dias Survey catalogue, in order to illustrate the quality of the fitting for a variety of SED shapes. The star AB Aur was used as a test of the GA parameter estimation, and demonstrates that the new code reproduces successfully a canonical example of the flared-disc model. The GA method gives a good quality of fit, but the range of input parameters must be chosen with caution, as unrealistic disc parameters can be derived. It is confirmed that the flared-disc model fits the flattened SEDs typical of Herbig stars; however, embedded objects (increasing SED slope) and debris discs (steeply decreasing SED slope) are not well fitted with this configuration. Even considering the limitation of the derived parameters, the automatic process of SED fitting provides an interesting tool for the statistical analysis of the circumstellar luminosity of large samples of young stars.

  16. Prevalence of disc cupping in non-glaucomatous eyes

    Directory of Open Access Journals (Sweden)

    José Pablo Chiappe

    2015-02-01

    Full Text Available This study assessed optic disc size and cupping, using a commercially available ophthalmoscope, in order to show norms of these values for clinical practice. Subjects were office-workers referred from their respective workplaces for a routine medical examination, which included eye examination. The optic disc size was classified as small, medium or large, for having a diameter 1.5 times (respectively the diameter of the ophthalmoscope's selected light spot on the posterior pole. The cupping was classified as the ratio of the vertical cupping diameter and the vertical disc diameter on a relative decimal scale from 0.0 to 1.0.This study included 184 subjects with a mean age of 40.5 ± 9.5 years; 149 (81% were males. Their mean ocular pressure was 12.4 ± 1.5 mmHg (range 10-17 mmHg. There was a high correlation between optic disc sizes and cupping in the right and left eyes (Pearson Correlation r = 0.866, p < 0.001; therefore, for simplicity only the data for right eyes are presented. According to our definition, the optic discs in these eyes comprised 27 (14.7% small, 141 (76.6% medium and 16 (8.7% large. The small optic discs were rarely cupped, and the large optic discs were always cupped. Optic disc cupping greater than 0.7 was rarely found and should be suspect of glaucoma. Clinical doctors should be aware of this and refer those subjects with abnormal cupping to the specialist.

  17. HEAT TRANSIENT TRANSFER ANALYSIS OF BRAKE DISC /PAD SYSTEM

    OpenAIRE

    Thuppal Vedanta, Srivatsan; Kora, Naga Vamsi Krishna

    2016-01-01

    Braking is mainly controlled by the engine. Friction between a pair of pads and a rotating disc converts the kinetic energy of the vehicle into heat. High temperatures can be reached in the system which can be detrimental for both, components and passenger safety. Numerical techniques help simulate load cases and compute the temperatures field in brake disc and brake pads. The present work implements a Finite Element (FE) toolbox in Matlab/Simulink able to simulate different braking manoeuvre...

  18. Disc battery ingestion; a single event with different outcomes

    Directory of Open Access Journals (Sweden)

    E. Sindi

    2017-06-01

    Full Text Available Foreign body (FB ingestion is a common problem especially in children below the age of 5 years. This is fueled by their curiosity to explore their surroundings. The ingested foreign body finds its way out of the gastrointestinal tract without any serious consequences most of the time. On the other hand, disc battery ingestion has been reported to cause serious harm when ingested including death. We report two patients who had ingested disc batteries and their respective outcomes.

  19. An intervertebral disc whole organ culture system to investigate proinflammatory and degenerative disc disease condition.

    Science.gov (United States)

    Lang, Gernot; Liu, Yishan; Geries, Janna; Zhou, Zhiyu; Kubosch, David; Südkamp, Norbert; Richards, R Geoff; Alini, Mauro; Grad, Sibylle; Li, Zhen

    2018-04-01

    The aim of this study was to compare the effect of different disease initiators of degenerative disc disease (DDD) within an intervertebral disc (IVD) organ culture system and to understand the interplay between inflammation and degeneration in the early stage of DDD. Bovine caudal IVDs were cultured within a bioreactor for up to 11 days. Control group was cultured under physiological loading (0.02-0.2 MPa; 0.2 Hz; 2 hr/day) and high glucose (4.5 g/L) medium. Detrimental loading (0.32-0.5 MPa, 5 Hz; 2 hr/day) and low glucose (2 g/L) medium were applied to mimic the condition of abnormal mechanical stress and limited nutrition supply. Tumour necrosis factor alpha (TNF-α) was injected into the nucleus pulposus (100 ng per IVD) as a proinflammatory trigger. TNF-α combined with detrimental loading and low glucose medium up-regulated interleukin 1β (IL-1β), IL-6, and IL-8 gene expression in disc tissue, nitric oxide, and IL-8 release from IVD, which indicate a proinflammatory effect. The combined initiators up-regulated matrix metalloproteinase 1 gene expression, down-regulated gene expression of Type I collagen in annulus fibrosus and Type II collagen in nucleus pulposus, and reduced the cell viability. Furthermore, the combined initiators induced a degradative effect, as indicated by markedly higher glycosaminoglycan release into conditioned medium. The combination of detrimental dynamic loading, nutrient deficiency, and TNF-α intradiscal injection can synergistically simulate the proinflammatory and degenerative disease condition within DDD. This model will be of high interest to screen therapeutic agents in further preclinical studies for early intervention and treatment of DDD. Copyright © 2018 John Wiley & Sons, Ltd.

  20. Cranial thoracic disc protrusions in three German Shepherd dogs.

    Science.gov (United States)

    Gaitero, Lluís; Añor, Sònia

    2009-11-01

    Although intervertebral disc degeneration can occur at any level of the spine, cervical and thoraco-lumbar discs are more commonly affected. The presence of the inter-capital ligament between the rib heads results in an extremely low incidence of cranial thoracic intervertebral disc herniation. In this case series, the clinical, radiological, and surgical findings, as well as the post-operative outcome, in three German Shepherd dogs with T2-T3 disc protrusions is reported. These dogs had chronic progressive paraparesis and lumbar myelography and post-myelographic computerised tomography revealed ventrolateral, extra-dural spinal cord compressions over the T2-T3 intervertebral disc. All animals exhibited transient deterioration in their clinical signs and one developed unilateral Horner's syndrome following T2-T3 hemi-dorsal laminectomy. Subsequently two of the dogs improved progressively and neurological dysfunction had completely resolved by 2 months. To the authors' knowledge, this is the first case series describing T2-T3 disc protrusions in the dog.

  1. Concomitance of fibromyalgia syndrome and cervical disc herniation.

    Science.gov (United States)

    Güler, Mustafa; Aydın, Teoman; Akgöl, Erdal; Taşpınar, Özgür

    2015-03-01

    [Purpose] Fibromyalgia syndrome (FMS) and cervical disc herniation (CDH) are a common diseases commonly encountered in physical therapy clinics. There are also patients who have both of these diseases. In this study we aim to investigated whether FMS is a risk factor for cervical disc herniation and the frequency of their coincident occurrence. [Subjects and Methods] Thirty-five patients having a primary FMS diagnosis according to the American Rheumatism Association criteria are taken into consideration and a control group were the subjects of this study. The two groups were compared with respect to cervical disc hernia using cervical region MRI. [Results] The distribution of disc hernia of 6 fibromyalgia patients who had cervical discopathy was: 16.6% C2-3, 16.6% C5-6, 16.6% C6-7, 33.3% C4-5, C5-6 (two levels in two patients) and 16.6% C4-5, C5-6, C7-1 (three levels in one patient) . The herniation directions were given as: central in 5 levels, right paramedian in 1 level, and left paramedian disc hernia in 1 level. There were 4 cervical disk hernia in the control group. The herniation direction were central in two, right paramedian in one, and left paramedian in one patient. [Conclusion] In this study, the existence of cervical disc herniation in fibromyalgia patients was found to be not different from the normal population.

  2. Histological Identification of Propionibacterium acnes in Nonpyogenic Degenerated Intervertebral Discs

    Directory of Open Access Journals (Sweden)

    Ye Yuan

    2017-01-01

    Full Text Available Purpose. Low-virulence anaerobic bacteria, especially the Propionibacterium acnes (P. acnes, have been thought to be a new pathogeny for a series of disc diseases. However, until now, there has been no histological evidence to confirm this link. The purpose of this study was to confirm the presence of P. acnes in nonpyogenic intervertebral discs via histological observation. Method. Degenerated intervertebral discs were harvested from 76 patients with low back pain and/or sciatica but without any symptoms of discitis or spondylodiscitis. The samples were cultured under anaerobic conditions and then examined using 16S rDNA PCR to screen for P. acnes. Samples found to be positive for P. acnes were stained with hematoxylin-eosin (HE and modified Brown-Brenn staining and observed under a microscope. Results. Here, 16 intervertebral discs were found to be positive for P. acnes via 16S rDNA PCR and the prevalence was 21.05% (16/76. Among them, 7 samples had visible microbes stained with HE and modified Brown-Brenn staining. Morphological examination showed the bacteria to be Gram-positive and rod-shaped, so they were considered P. acnes. Conclusion. P. acnes is capable of colonizing some degenerated intervertebral discs without causing discitis, and its presence could be further confirmed by histological evidence. Targeting these bacteria may be a promising therapy method for some disc diseases.

  3. Degenerated human intervertebral discs contain autoantibodies against extracellular matrix proteins

    Directory of Open Access Journals (Sweden)

    S Capossela

    2014-04-01

    Full Text Available Degeneration of intervertebral discs (IVDs is associated with back pain and elevated levels of inflammatory cells. It has been hypothesised that discogenic pain is a direct result of vascular and neural ingrowth along annulus fissures, which may expose the avascular nucleus pulposus (NP to the systemic circulation and induce an autoimmune reaction. In this study, we confirmed our previous observation of antibodies in human degenerated and post-traumatic IVDs cultured in vitro. We hypothesised that the presence of antibodies was due to an autoimmune reaction against specific proteins of the disc. Furthermore we identified antigens which possibly trigger an autoimmune response in degenerative disc diseases. We demonstrated that degenerated and post-traumatic IVDs contain IgG antibodies against typical extracellular proteins of the disc, particularly proteins of the NP. We identified IgGs against collagen type II and aggrecan, confirming an autoimmune reaction against the normally immune privileged NP. We also found specific IgGs against collagens types I and V, but not against collagen type III. In conclusion, this study confirmed the association between disc degeneration and autoimmunity, and may open the avenue for future studies on developing prognostic, diagnostic and therapy-monitoring markers for degenerative disc diseases.

  4. Vortex survival in 3D self-gravitating accretion discs

    Science.gov (United States)

    Lin, Min-Kai; Pierens, Arnaud

    2018-04-01

    Large-scale, dust-trapping vortices may account for observations of asymmetric protoplanetary discs. Disc vortices are also potential sites for accelerated planetesimal formation by concentrating dust grains. However, in 3D discs vortices are subject to destructive `elliptic instabilities', which reduces their viability as dust traps. The survival of vortices in 3D accretion discs is thus an important issue to address. In this work, we perform shearing box simulations to show that disc self-gravity enhances the survival of 3D vortices, even when self-gravity is weak in the classic sense (e.g. with a Toomre Q ≃ 5). We find a 3D, self-gravitating vortex can grow on secular timescales in spite of the elliptic instability. The vortex aspect-ratio decreases as it strengthens, which feeds the elliptic instability. The result is a 3D vortex with a turbulent core that persists for ˜103 orbits. We find when gravitational and hydrodynamic stresses become comparable, the vortex may undergo episodic bursts, which we interpret as interaction between elliptic and gravitational instabilities. We estimate the distribution of dust particles in self-gravitating, turbulent vortices. Our results suggest large-scale vortices in protoplanetary discs are more easily observed at large radii.

  5. Concomitance of fibromyalgia syndrome and cervical disc herniation

    Science.gov (United States)

    Güler, Mustafa; Aydın, Teoman; Akgöl, Erdal; Taşpınar, Özgür

    2015-01-01

    [Purpose] Fibromyalgia syndrome (FMS) and cervical disc herniation (CDH) are a common diseases commonly encountered in physical therapy clinics. There are also patients who have both of these diseases. In this study we aim to investigated whether FMS is a risk factor for cervical disc herniation and the frequency of their coincident occurrence. [Subjects and Methods] Thirty-five patients having a primary FMS diagnosis according to the American Rheumatism Association criteria are taken into consideration and a control group were the subjects of this study. The two groups were compared with respect to cervical disc hernia using cervical region MRI. [Results] The distribution of disc hernia of 6 fibromyalgia patients who had cervical discopathy was: 16.6% C2–3, 16.6% C5–6, 16.6% C6–7, 33.3% C4–5, C5–6 (two levels in two patients) and 16.6% C4–5, C5–6, C7–1 (three levels in one patient) . The herniation directions were given as: central in 5 levels, right paramedian in 1 level, and left paramedian disc hernia in 1 level. There were 4 cervical disk hernia in the control group. The herniation direction were central in two, right paramedian in one, and left paramedian in one patient. [Conclusion] In this study, the existence of cervical disc herniation in fibromyalgia patients was found to be not different from the normal population. PMID:25931731

  6. Laser Disc Decompression In Emam Khomeini Hospital 1996-1999

    Directory of Open Access Journals (Sweden)

    Ghaffar Poor. M

    2002-07-01

    Full Text Available Low back pain is among the most frequent medical complaints and a major public health problem. 1.7 percent of cases are caused by herniated disc, 20 percent of which require interventional treatment. Percutaneous laser disc decompression (P.L.DD can be considered as an effective therapeutic alternative in certain cases."nMaterials and Methods: To determine the efficacy of this method in Iran in patient's with low back pain due to disc herniation, 40 patients according to medical history, physical examination and MRI findings were selected for this study. Patients who had canal stenosis, marginal, osteophyte, advanced disc dehydration, ruptured posterior ligament and other contraindication were excluded. CT scan was used only for needle navigation. After proper positioning of needle, nucleous pulposus was evapourated with Nd-YAG laser. Total energy was 1200-1600j. The procedure was done out patient and follow up has been done at 1 day, 1 week, 1,3, 6 and 12 months."nResults: There was no serious complication. 80 percent of patients in one-year follow up showed significant clinical improvement."nConclusion: Our findings suggests that percutaneous laser disc decompression can be considered as an effective alternative method of treatment for disc herniation and patient selection is the critical factor which determines success rate.

  7. GES DISC Data Recipes in Jupyter Notebooks

    Science.gov (United States)

    Li, A.; Banavige, B.; Garimella, K.; Rice, J.; Shen, S.; Liu, Z.

    2017-12-01

    The Earth Science Data and Information System (ESDIS) Project manages twelve Distributed Active Archive Centers (DAACs) which are geographically dispersed across the United States. The DAACs are responsible for ingesting, processing, archiving, and distributing Earth science data produced from various sources (satellites, aircraft, field measurements, etc.). In response to projections of an exponential increase in data production, there has been a recent effort to prototype various DAAC activities in the cloud computing environment. This, in turn, led to the creation of an initiative, called the Cloud Analysis Toolkit to Enable Earth Science (CATEES), to develop a Python software package in order to transition Earth science data processing to the cloud. This project, in particular, supports CATEES and has two primary goals. One, transition data recipes created by the Goddard Earth Science Data and Information Service Center (GES DISC) DAAC into an interactive and educational environment using Jupyter Notebooks. Two, acclimate Earth scientists to cloud computing. To accomplish these goals, we create Jupyter Notebooks to compartmentalize the different steps of data analysis and help users obtain and parse data from the command line. We also develop a Docker container, comprised of Jupyter Notebooks, Python library dependencies, and command line tools, and configure it into an easy to deploy package. The end result is an end-to-end product that simulates the use case of end users working in the cloud computing environment.

  8. Pathogenesis of optic disc edema in raised intracranial pressure.

    Science.gov (United States)

    Hayreh, Sohan Singh

    2016-01-01

    Optic disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of optic disc edema in raised intracranial pressure: the anatomy and blood supply of the optic nerve, the roles of the sheath of the optic nerve, of the centripetal flow of fluids along the optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of optic disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and optic disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of optic disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the optic nerve on the optic disc edema. This latter study showed that opening the sheath resulted in resolution of optic disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of optic disc edema. I also investigated optic disc edema with

  9. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  10. Accreting transition discs with large cavities created by X-ray photoevaporation in C and O depleted discs

    Science.gov (United States)

    Ercolano, Barbara; Weber, Michael L.; Owen, James E.

    2018-01-01

    Circumstellar discs with large dust depleted cavities and vigorous accretion on to the central star are often considered signposts for (multiple) giant planet formation. In this Letter, we show that X-ray photoevaporation operating in discs with modest (factors 3-10) gas-phase depletion of carbon and oxygen at large radii ( > 15 au) yields the inner radius and accretion rates for most of the observed discs, without the need to invoke giant planet formation. We present one-dimensional viscous evolution models of discs affected by X-ray photoevaporation assuming moderate gas-phase depletion of carbon and oxygen, well within the range reported by recent observations. Our models use a simplified prescription for scaling the X-ray photoevaporation rates and profiles at different metallicity, and our quantitative result depends on this scaling. While more rigorous hydrodynamical modelling of mass-loss profiles at low metallicities is required to constrain the observational parameter space that can be explained by our models, the general conclusion that metal sequestering at large radii may be responsible for the observed diversity of transition discs is shown to be robust. Gap opening by giant planet formation may still be responsible for a number of observed transition discs with large cavities and very high accretion rate.

  11. Local stellar kinematics from RAVE data—VIII. Effects of the Galactic disc perturbations on stellar orbits of red clump stars

    Science.gov (United States)

    Önal Taş, Ö.; Bilir, S.; Plevne, O.

    2018-02-01

    We aim to probe the dynamic structure of the extended Solar neighborhood by calculating the radial metallicity gradients from orbit properties, which are obtained for axisymmetric and non-axisymmetric potential models, of red clump (RC) stars selected from the RAdial Velocity Experiment's Fourth Data Release. Distances are obtained by assuming a single absolute magnitude value in near-infrared, i.e. M_{Ks}=-1.54±0.04 mag, for each RC star. Stellar orbit parameters are calculated by using the potential functions: (i) for the MWPotential2014 potential, (ii) for the same potential with perturbation functions of the Galactic bar and transient spiral arms. The stellar age is calculated with a method based on Bayesian statistics. The radial metallicity gradients are evaluated based on the maximum vertical distance (z_{max}) from the Galactic plane and the planar eccentricity (ep) of RC stars for both of the potential models. The largest radial metallicity gradient in the 01 kpc, the radial metallicity gradients have zero or positive values and they do not depend on ep subsamples. There is a large radial metallicity gradient for thin disc, but no radial gradient found for thick disc. Moreover, the largest radial metallicity gradients are obtained where the outer Lindblad resonance region is effective. We claim that this apparent change in radial metallicity gradients in the thin disc is a result of orbital perturbation originating from the existing resonance regions.

  12. Thin film hydrogen sensor

    Science.gov (United States)

    Cheng, Yang-Tse; Poli, Andrea A.; Meltser, Mark Alexander

    1999-01-01

    A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

  13. A Picture-perfect Pure-disc Galaxy

    Science.gov (United States)

    2011-02-01

    The bright galaxy NGC 3621, captured here using the Wide Field Imager on the 2.2-metre telescope at ESO's La Silla Observatory in Chile, appears to be a fine example of a classical spiral. But it is in fact rather unusual: it does not have a central bulge and is therefore described as a pure-disc galaxy. NGC 3621 is a spiral galaxy about 22 million light-years away in the constellation of Hydra (The Sea Snake). It is comparatively bright and can be seen well in moderate-sized telescopes. This picture was taken using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile. The data were selected from the ESO archive by Joe DePasquale as part of the Hidden Treasures competition [1]. Joe's picture of NGC 3621 was ranked fifth in the competition. This galaxy has a flat pancake shape, indicating that it hasn't yet come face to face with another galaxy as such a galactic collision would have disturbed the thin disc of stars, creating a small bulge in its centre. Most astronomers think that galaxies grow by merging with other galaxies, in a process called hierarchical galaxy formation. Over time, this should create large bulges in the centres of spirals. Recent research, however, has suggested that bulgeless, or pure-disc, spiral galaxies like NGC 3621 are actually fairly common. This galaxy is of further interest to astronomers because its relative proximity allows them to study a wide range of astronomical objects within it, including stellar nurseries, dust clouds, and pulsating stars called Cepheid variables, which astronomers use as distance markers in the Universe [2]. In the late 1990s, NGC 3621 was one of 18 galaxies selected for a Key Project of the Hubble Space Telescope: to observe Cepheid variables and measure the rate of expansion of the Universe to a higher accuracy than had been possible before. In the successful project, 69 Cepheid variables were observed in this galaxy alone. Multiple monochrome images taken through

  14. Mass Distribution in Rotating Thin-Disk Galaxies According to Newtonian Dynamics

    Directory of Open Access Journals (Sweden)

    James Q. Feng

    2014-04-01

    Full Text Available An accurate computational method is presented for determining the mass distribution in a mature spiral galaxy from a given rotation curve by applying Newtonian dynamics for an axisymmetrically rotating thin disk of finite size with or without a central spherical bulge. The governing integral equation for mass distribution is transformed via a boundary-element method into a linear algebra matrix equation that can be solved numerically for rotation curves with a wide range of shapes. To illustrate the effectiveness of this computational method, mass distributions in several mature spiral galaxies are determined from their measured rotation curves. All the surface mass density profiles predicted by our model exhibit approximately a common exponential law of decay, quantitatively consistent with the observed surface brightness distributions. When a central spherical bulge is present, the mass distribution in the galaxy is altered in such a way that the periphery mass density is reduced, while more mass appears toward the galactic center. By extending the computational domain beyond the galactic edge, we can determine the rotation velocity outside the cut-off radius, which appears to continuously decrease and to gradually approach the Keplerian rotation velocity out over twice the cut-off radius. An examination of circular orbit stability suggests that galaxies with flat or rising rotation velocities are more stable than those with declining rotation velocities especially in the region near the galactic edge. Our results demonstrate the fact that Newtonian dynamics can be adequate for describing the observed rotation behavior of mature spiral galaxies.

  15. Biomechanical analysis of the camelid cervical intervertebral disc

    Directory of Open Access Journals (Sweden)

    Dean K. Stolworthy

    2015-01-01

    Full Text Available Chronic low back pain (LBP is a prevalent global problem, which is often correlated with degenerative disc disease. The development and use of good, relevant animal models of the spine may improve treatment options for this condition. While no animal model is capable of reproducing the exact biology, anatomy, and biomechanics of the human spine, the quality of a particular animal model increases with the number of shared characteristics that are relevant to the human condition. The purpose of this study was to investigate the camelid (specifically, alpaca and llama cervical spine as a model of the human lumbar spine. Cervical spines were obtained from four alpacas and four llamas and individual segments were used for segmental flexibility/biomechanics and/or morphology/anatomy studies. Qualitative and quantitative data were compared for the alpaca and llama cervical spines, and human lumbar specimens in addition to other published large animal data. Results indicate that a camelid cervical intervertebral disc (IVD closely approximates the human lumbar disc with regard to size, spinal posture, and biomechanical flexibility. Specifically, compared with the human lumbar disc, the alpaca and llama cervical disc size are approximately 62%, 83%, and 75% with regard to area, depth, and width, respectively, and the disc flexibility is approximately 133%, 173%, and 254%, with regard to range of motion (ROM in axial-rotation, flexion-extension, and lateral-bending, respectively. These results, combined with the clinical report of disc degeneration in the llama lower cervical spine, suggest that the camelid cervical spine is potentially well suited for use as an animal model in biomechanical studies of the human lumbar spine.

  16. Extracellular matrix remodeling in experimental intervertebral disc degeneration.

    Science.gov (United States)

    de Oliveira, Cintia Pereira; Rodrigues, Luciano Miller Reis; Fregni, Maria Vitória Ventura Dias; Gotfryd, Alberto; Made, Ana Maria; Pinhal, Maria Aparecida da Silva

    2013-05-01

    To evaluate the remodeling of the extracellular matrix in intervertebral disc degeneration through the experimental model of intervertebral disc degeneration. The model of disc degeneration induction, using needle 20G and 360° rotation, was applied for 30 seconds between the 6(th)/7(th), and 8(th)/9(th) coccygeal vertebrae of Wistar rats. The intermediary level, between the 7(th) and 8(th) vertebrae, was taken as control, not being subjected puncture. The distribution of the extracellular matrix components involved in the remodeling and inflammation process, such as proteoglycans (aggrecan, decorin, biglycan), growth factors (TGFβ), heparanase isoforms (HPSE1, HPSE2), metaloprotesasis-9 (MMP9) and interleukins (IL-6, IL-10) was analyzed during the post-injury period (15 to 30 days) and in the control group (discs collected immediately after the puncture, day zero). On the 15(th) day, acute phase of the disease, a reduced expression of extracellular matrix components had been observed, whilst there were no differences in the interleukins expression. At 30 days, the molecules followed a very similar pattern of expression in the control group (not affected by disc degeneration). The results show that during the acute phase significant alterations in the extracellular matrix components occur and in the late phase intervertebral disc returns to a profile similar to noninvolved tissue, probably due to extensive remodeling process of the extracellular matrix that is capable of regenerating the damaged tissue. : The experimental model used demonstrated the occurrence of significant changes in the extracellular matrix during the period analyzed after induction of intervertebral disc degeneration. Laboratory investigation.

  17. Genetic association studies in lumbar disc degeneration: a systematic review.

    Directory of Open Access Journals (Sweden)

    Pasi J Eskola

    Full Text Available Low back pain is associated with lumbar disc degeneration, which is mainly due to genetic predisposition. The objective of this study was to perform a systematic review to evaluate genetic association studies in lumbar disc degeneration as defined on magnetic resonance imaging (MRI in humans.A systematic literature search was conducted in MEDLINE, MEDLINE In-Process, SCOPUS, ISI Web of Science, The Genetic Association Database and The Human Genome Epidemiology Network for information published between 1990-2011 addressing genes and lumbar disc degeneration. Two investigators independently identified studies to determine inclusion, after which they performed data extraction and analysis. The level of cumulative genetic association evidence was analyzed according to The HuGENet Working Group guidelines.Fifty-two studies were included for review. Forty-eight studies reported at least one positive association between a genetic marker and lumbar disc degeneration. The phenotype definition of lumbar disc degeneration was highly variable between the studies and replications were inconsistent. Most of the associations presented with a weak level of evidence. The level of evidence was moderate for ASPN (D-repeat, COL11A1 (rs1676486, GDF5 (rs143383, SKT (rs16924573, THBS2 (rs9406328 and MMP9 (rs17576.Based on this first extensive systematic review on the topic, the credibility of reported genetic associations is mostly weak. Clear definition of lumbar disc degeneration phenotypes and large population-based cohorts are needed. An international consortium is needed to standardize genetic association studies in relation to disc degeneration.

  18. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  19. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...

  20. Frontal cortical synaptic communication is abnormal in Disc1 genetic mouse models of schizophrenia.

    Science.gov (United States)

    Holley, Sandra M; Wang, Elizabeth A; Cepeda, Carlos; Jentsch, J David; Ross, Christopher A; Pletnikov, Mikhail V; Levine, Michael S

    2013-05-01

    Mouse models carrying Disc1 mutations may provide insights into how Disc1 genetic variations contribute to schizophrenia (SZ) susceptibility. Disc1 mutant mice show behavioral and cognitive disturbances reminiscent of SZ. To dissect the synaptic mechanisms underlying these phenotypes, we examined electrophysiological properties of cortical neurons from two mouse models, the first expressing a truncated mouse Disc1 (mDisc1) protein throughout the entire brain, and the second expressing a truncated human Disc1 (hDisc1) protein in forebrain regions. We obtained whole-cell patch clamp recordings to examine how altered expression of Disc1 protein changes excitatory and inhibitory synaptic transmissions onto cortical pyramidal neurons in the medial prefrontal cortex in 4-7 month-old mDisc1 and hDisc1 mice. In both mDisc1 and hDisc1 mice, the frequency of spontaneous EPSCs was greater than in wild-type littermate controls. Male mice from both lines were more affected by the Disc1 mutation than were females, exhibiting increases in the ratio of excitatory to inhibitory events. Changes in spontaneous IPSCs were only observed in the mDisc1 model and were sex-specific, with diminished cortical GABAergic neurotransmission, a well-documented characteristic of SZ, occurring only in male mDisc1 mice. In contrast, female mDisc1 mice showed an increase in the frequency of small-amplitude sIPSCs. These findings indicate that truncations of Disc1 alter glutamatergic and GABAergic neurotransmission both commonly and differently in the models and some of the effects are sex-specific, revealing how altered Disc1 expression may contribute to behavioral disruptions and cognitive deficits of SZ. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Thin epitaxial silicon detectors

    International Nuclear Information System (INIS)

    Stab, L.

    1989-01-01

    Manufacturing procedures of thin epitaxial surface barriers will be given. Some improvements have been obtained: larger areas, lower leakage currents and better resolutions. New planar epitaxial dE/dX detectors, made in a collaboration work with ENERTEC-INTERTECHNIQUE, and a new application of these thin planar diodes to EXAFS measurements, made in a collaboration work with LURE (CNRS,CEA,MEN) will also be reported

  2. Multifunctional thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

    2015-10-13

    A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

  3. Thinning 'Elstar' apple with benzyladenine

    NARCIS (Netherlands)

    Maas, F.M.

    2006-01-01

    ‘Elstar’, the main apple cultivar grown in the Netherlands, requires adequate thinning to reach marketable fruit sizes and to achieve regular yields by preventing alternate bearing. At the moment, chemical thinning of ‘Elstar’ is the only economically feasible way of thinning. Thinning by hand is

  4. Fluoroscopic-guided intradiscal oxygen-ozone injection therapy for thoracolumbar intervertebral disc herniations in dogs.

    Science.gov (United States)

    Han, Hyun-Jung; Kim, Joon-Young; Jang, Ha-Young; Lee, Bora; Yoon, Jung-Hee; Jang, Sang-Keun; Choi, Seok Hwa; Jeong, Soon-Wuk

    2007-01-01

    To investigate the effect of oxygen-ozone (O2-O3) injection on thoracolumbar intervertebral disc herniation (IVDH) in dogs. Ten herniated discs of five dogs were treated with percutaneous injection of an O2-O3 gas mixture with O3 concentration of 32 microg/microl intradiscally (1.5-2 microl) under fluoroscopy guidance. Five weeks after treatment, the mean size of herniated discs was measured by computed tomography and showed significant reduction of disc volumes in all animals (8.8%+/-3.82%). The degree of shrinkage was negatively linearly correlated with disc mineralization (correlation coefficient=-0.636) and statistically significant at pdiscs by disc shrinkage.

  5. Research on anti crack mechanism of bionic coupling brake disc

    Science.gov (United States)

    Shi, Lifeng; Yang, Xiao; Zheng, Lingnan; Wu, Can; Ni, Jing

    2017-09-01

    According to the biological function of fatigue resistance possessed by biology, this study designed a Bionic Coupling Brake Disc (BCBD) which can inhibit crack propagation as the result of improving fatigue property. Thermal stress field of brake disc was calculated under emergency working condition, and circumferential and radial stress field which lead to fatigue failure of brake disc were investigated simultaneously. Results showed that the maximum temperature of surface reached 890°C and the maximum residual tensile stress was 207 Mpa when the initial velocity of vehicle was 200 km/h. Based on the theory of elastic plastic fracture mechanics, the crack opening displacement and the crack front J integrals of the BCBD and traditional brake disc (TBD) with pre-cracking were calculated, and the strength of crack front was compared. Results revealed the growth behavior of fatigue crack located on surface of brake disc, and proved the anti fatigue resistance of BCBD was better, and the strength of crack resistance of BCBD was much stronger than that of TBD. This simulation research provided significant references for optimization and manufacturing of BCBD.

  6. Bladed disc crack diagnostics using blade passage signals

    Science.gov (United States)

    Hanachi, Houman; Liu, Jie; Banerjee, Avisekh; Koul, Ashok; Liang, Ming; Alavi, Elham

    2012-12-01

    One of the major potential faults in a turbo fan engine is the crack initiation and propagation in bladed discs under cyclic loads that could result in the breakdown of the engines if not detected at an early stage. Reliable fault detection techniques are therefore in demand to reduce maintenance cost and prevent catastrophic failures. Although a number of approaches have been reported in the literature, it remains very challenging to develop a reliable technique to accurately estimate the health condition of a rotating bladed disc. Correspondingly, this paper presents a novel technique for bladed disc crack detection through two sequential signal processing stages: (1) signal preprocessing that aims to eliminate the noises in the blade passage signals; (2) signal postprocessing that intends to identify the crack location. In the first stage, physics-based modeling and interpretation are established to help characterize the noises. The crack initiation can be determined based on the calculated health monitoring index derived from the sinusoidal effects. In the second stage, the crack is located through advanced detrended fluctuation analysis of the preprocessed data. The proposed technique is validated using a set of spin rig test data (i.e. tip clearance and time of arrival) that was acquired during a test conducted on a bladed military engine fan disc. The test results have demonstrated that the developed technique is an effective approach for identifying and locating the incipient crack that occurs at the root of a bladed disc.

  7. Quantitative measurement of intervertebral disc signal using MRI

    International Nuclear Information System (INIS)

    Niemelaeinen, R.; Videman, T.; Dhillon, S.S.; Battie, M.C.

    2008-01-01

    Aim: To investigate the spinal cord as an alternative intra-body reference to cerebrospinal fluid (CSF) in evaluating thoracic disc signal intensity. Materials and methods: T2-weighted magnetic resonance imaging (MRI) images of T6-T12 were obtained using 1.5 T machines for a population-based sample of 523 men aged 35-70 years. Quantitative data on the signal intensities were acquired using an image analysis program (SpEx (copy right) ). A random sample of 30 subjects and intraclass correlation coeffcients (ICC) were used to examine the repeatability of the spinal cord measurements. The validity of using the spinal cord as a reference was examined by correlating cord and CSF samples. Finally, thoracic disc signal was validated by correlating it with age without adjustment and adjusting for either cord or CSF. Pearson's r was used for correlational analyses. Results: The repeatability of the spinal cord signal measurements was extremely high (≥0.99). The correlations between the signals of spinal cord and CSF by level were all above 0.9. The spinal cord-adjusted disc signal and age correlated similarly with CSF-adjusted disc signal and age (r = -0.30 to -0.40 versus r = -0.26 to -0.36). Conclusion: Adjacent spinal cord is a good alternative reference to the current reference standard, CSF, for quantitative measurements of disc signal intensity. Clearly fewer levels were excluded when using spinal cord as compared to CSF due to missing reference samples

  8. Transforaminal Approach in Thoracal Disc Pathologies: Transforaminal Microdiscectomy Technique

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    Sedat Dalbayrak

    2014-01-01

    Full Text Available Objective. Many surgical approaches have been defined and implemented in the last few decades for thoracic disc herniations. The endoscopic foraminal approach in foraminal, lateral, and far lateral disc hernias is a contemporary minimal invasive approach. This study was performed to show that the approach is possible using the microscope without an endoscope, and even the intervention on the discs within the spinal canal is possible by having access through the foramen. Methods. Forty-two cases with disc hernias in the medial of the pedicle were included in this study; surgeries were performed with transforaminal approach and microsurgically. Extraforaminal disc hernias were not included in the study. Access was made through the Kambin triangle, foramen was enlarged, and spinal canal was entered. Results. The procedure took 65 minutes in the average, and the mean bleeding amount was about 100cc. They were mobilized within the same day postoperatively. No complications were seen. Follow-up periods range between 5 and 84 months, and the mean follow-up period is 30.2 months. Conclusion. Transforaminal microdiscectomy is a method that can be performed in any clinic with standard spinal surgery equipment. It does not require additional equipment or high costs.

  9. Orthogonal versus covariant Lyapunov vectors for rough hard disc systems

    Science.gov (United States)

    Bosetti, H.; Posch, H. A.

    2013-06-01

    The Oseledec splitting of the tangent space into covariant subspaces for a hyperbolic dynamical system is numerically accessible by computing the full set of covariant Lyapunov vectors. In this paper, the covariant Lyapunov vectors, the orthogonal Gram-Schmidt vectors and the corresponding local (time-dependent) Lyapunov exponents are analyzed for a planar system of rough hard discs (RHDS). These results are compared to respective results for a smooth-hard-disc system (SHDS). We find that the rotation of the discs deeply affects the Oseledec splitting and the structure of the tangent space. For both the smooth and rough hard discs, the stable, unstable and central manifolds are transverse to each other, although the minimal angle between the unstable and stable manifolds of the RHDS typically is very small. Both systems are hyperbolic. However, the central manifold is precisely orthogonal to the rest of the tangent space only for the smooth-particle case and not for the rough discs. We also demonstrate that the rotations destroy the Hamiltonian (symplectic) character for the RHDS. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Lyapunov analysis: from dynamical systems theory to applications’.

  10. The magnetorotational instability in debris-disc gas

    Science.gov (United States)

    Kral, Quentin; Latter, Henrik

    2016-09-01

    Debris discs are commonly swathed in gas, which can be observed in UV, in fine structure lines in FIR, and in resolved maps of CO emission. Carbon and oxygen are overabundant in such gas, but it is severely depleted in hydrogen. As a consequence, its ionization fraction is remarkably high, suggesting that magnetohydrodynamic (MHD) processes could be important. In particular, the gas may be subject to the magnetorotational instability (MRI), and indeed, recent modelling of β Pictoris requires an anomalous viscosity to explain the gas's observed radial structure. In this paper, we explore the possibility that the MRI is active in debris-disc gas and responsible for the observed mass transport. We find that non-ideal MHD and dust-gas interactions play a subdominant role, and that linear instability is viable at certain radii. However, owing to low gas densities, the outer parts of the disc could be stabilized by a weak ambient magnetic field, though it is difficult to constrain such a field. Even if the MRI is stabilized by too strong a field, a magnetocentrifugal wind may be launched in its place, and this could lead to equivalent (non-turbulent) transport. Numerical simulations of the vertically stratified MRI in conditions appropriate to the debris-disc gas should be able to determine the nature of the characteristic behaviour at different radii, and decide on the importance of the MRI (and MHD more generally) on the evolution of these discs.

  11. A Symptomatic Spinal Extradural Arachnoid Cyst with Lumbar Disc Herniation

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    Yoshinori Kadono

    2015-01-01

    Full Text Available Spinal epidural arachnoid cyst (EAC is a rare, usually asymptomatic condition of unknown origin, which typically involves the lower thoracic spine. We report a case of posttraumatic symptomatic EAC with lumbar disc herniation. A 22-year-old man experienced back pain and sciatica after a traffic accident. Neurological examination revealed a right L5 radiculopathy. Magnetic resonance imaging demonstrated a cystic lesion at the L3 to L5 level and an L4-5 disc herniation; computed tomography myelography showed that the right L5 root was sandwiched between the cyst and the herniation. A dural defect was identified during surgery. The cyst was excised completely and the defect was repaired. A herniation was excised beside the dural sac. Histology showed that the cyst wall consisted of collagen and meningothelial cells. Postoperatively the symptoms resolved. Lumbar spinal EACs are rare; such cysts may arise from a congenital dural crack and grow gradually. The 6 cases of symptomatic lumbar EAC reported in the literature were not associated with disc herniation or trauma. In this case, the comorbid disc herniation was involved in symptom progression. Although many EACs are asymptomatic, comorbid spinal disorders such as disc herniation or trauma can result in symptom progression.

  12. A potential role of thymic stromal lymphopoietin in the recruitment of macrophages to mouse intervertebral disc cells via monocyte chemotactic protein 1 induction: implications for herniated discs.

    Science.gov (United States)

    Ohba, Tetsuro; Haro, Hirotaka; Ando, Takashi; Koyama, Kensuke; Hatsushika, Kyosuke; Suenaga, Fumiko; Ohnuma, Yuko; Nakamura, Yuki; Katoh, Ryohei; Ogawa, Hideoki; Hamada, Yoshiki; Nakao, Atsuhito

    2008-11-01

    To determine whether thymic stromal lymphopoietin (TSLP) plays a role in the resorption of herniated disc tissue. The expression of TSLP messenger RNA (mRNA) and protein in mouse intervertebral disc cells was assessed by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA), and immunohistochemical analysis. The ability of mouse intervertebral disc cells to respond to TSLP stimulation was examined by Western blot analysis, ELISA, and protein array analysis. Intracellular signaling pathways involved in TSLP signaling in mouse intervertebral disc cells were investigated using several chemical inhibitors. The role of TSLP in macrophage migration into the intervertebral disc was assessed by in vitro migration assay. Finally, TSLP expression in clinical specimens derived from patients with a herniated disc was examined by immunohistochemistry. Mouse intervertebral disc cells expressed TSLP mRNA and protein upon stimulation with NF-kappaB-activating ligands such as tumor necrosis factor alpha. In addition, the mouse intervertebral disc cells expressed the TSLP receptor and produced monocyte chemotactic protein 1 (MCP-1; CCL2) and macrophage colony-stimulating factor in response to TSLP stimulation. Both anulus fibrosus and nucleus pulposus intervertebral disc cells expressed MCP-1 upon TSLP stimulation, which was mediated via the phosphatidylinositol 3-kinase/Akt pathway. Consistently, the supernatants of TSLP-activated intervertebral disc cultures had the capacity to induce macrophage migration in an MCP-1-dependent manner. Finally, TSLP and MCP-1 were coexpressed in human herniated disc specimens in which macrophage infiltration into the tissue was observed. TSLP induced by NF-kappaB-activating ligands in intervertebral discs may contribute to the recruitment of macrophages to the intervertebral disc by stimulating MCP-1 production and may be involved in the resorption of herniated disc tissue.

  13. Kinetic magnetic resonance imaging analysis of lumbar segmental motion at levels adjacent to disc herniation.

    Science.gov (United States)

    Lao, Lifeng; Daubs, Michael D; Takahashi, Shinji; Lord, Elizabeth L; Cohen, Jeremiah R; Zhong, Guibin; Wang, Jeffrey C

    2016-01-01

    A retrospective radiographic study was carried out to analyze the effect of lumbar disc herniation on the kinetic motion of adjacent segments. A total of 162 patients with low back pain or radicular pain in the lower limbs without a prior history of surgery were evaluated using kinetic magnetic resonance imaging. Translational motion, angular variation, and disc height were measured at each segment from L1-L2 to L5-S1. Other factors including the degree of disc degeneration, age, gender, and vertebral segment location were analyzed to determine any predisposing risk factors for segmental instability adjacent to disc herniations. Spinal levels above the disc herniation exhibited, on average, a 6.4 % increase in translational motion per mm of disc herniation (P = 0.496) and a 21.4 % increase in angular motion per mm herniation (P = 0.447). Levels below the herniation demonstrated a 5.2 % increase in translational motion per mm of disc herniation (P = 0.428) and a decrease of 10.7 % in angular motion per mm (P = 0.726). The degree of disc degeneration had no significant correlation with adjacent level motion. Similarly, disc herniation was not significantly correlated with disc height at adjacent levels, although there was a significant relationship between gender and adjacent segment disc height. Although disc height, translational motion, and angular variation are significantly affected at the level of a disc herniation, no significant changes are apparent in adjacent segments. Our results indicate that herniated discs have no effect on range of motion at adjacent levels regardless of the degree of disc degeneration or the size of disc herniation, suggesting that the natural progression of disc degeneration and adjacent segment disease may be separate, unrelated processes within the lumbar spine.

  14. Percutaneous Treatment of Herniated Lumbar Discs with Ozone: Investigation of the Mechanisms of Action.

    Science.gov (United States)

    Murphy, Kieran; Elias, Gavin; Steppan, Jim; Boxley, Chett; Balagurunathan, Kuberan; Victor, Xylophone; Meaders, Thomas; Muto, Mario

    2016-08-01

    To elucidate the mechanism of action of intradiscal oxygen-ozone therapy for herniated intervertebral disc therapy. Ozone's mechanism of action was investigated using 3 approaches: mathematical models of intervertebral disc space to explore the relationship between disc pressure and volume; ozonolysis experiments using glycosaminoglycans (GAGs) from a Chinese hamster ovary cell line that were similar in composition to GAGs found in human nucleus pulposus; and experiments in which live Yucatan miniature pigs received various concentrations of percutaneous, image-guided intradiscal oxygen-ozone treatment and were examined (after sacrifice) with histology and semiquantitative analysis of disc cytokine concentrations. Engineering calculations support observations that a small (6%) disc volume reduction can result in considerable (9.84%) intradiscal pressure reduction. Porcine disc histology and Chinese hamster ovary GAG ozonolysis results showed that administered ozone reacted with and fragmented disc proteoglycans, reducing disc volume through disc dehydration. Cytokine analysis of porcine discs found that each of 4 cytokines measured (interleukin [IL]-1β, IL-6, IL-8, and tumor necrosis factor α) increased in concentration after 2 wt% ozone treatment. Oxygen-ozone therapy breaks down proteoglycan GAGs that maintain disc osmotic pressure, dehydrating the nucleus pulposus and reducing intervertebral disc volume. This is likely a primary mechanism by which ozone relieves nerve root compression and alleviates herniated disc-related pain. Additionally, 2 wt% ozone appears to interact with intradiscal cytokines, generating an antiinflammatory response that may contribute to symptom improvement. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

  15. Investigation of Product Performance of Al-Metal Matrix Composites Brake Disc using Finite Element Analysis

    International Nuclear Information System (INIS)

    Fatchurrohman, N; Marini, C D; Suraya, S; Iqbal, AKM Asif

    2016-01-01

    The increasing demand of fuel efficiency and light weight components in automobile sectors have led to the development of advanced material parts with improved performance. A specific class of MMCs which has gained a lot of attention due to its potential is aluminium metal matrix composites (Al-MMCs). Product performance investigation of Al- MMCs is presented in this article, where an Al-MMCs brake disc is analyzed using finite element analysis. The objective is to identify the potentiality of replacing the conventional iron brake disc with Al-MMCs brake disc. The simulation results suggested that the MMCs brake disc provided better thermal and mechanical performance as compared to the conventional cast iron brake disc. Although, the Al-MMCs brake disc dissipated higher maximum temperature compared to cast iron brake disc's maximum temperature. The Al-MMCs brake disc showed a well distributed temperature than the cast iron brake disc. The high temperature developed at the ring of the disc and heat was dissipated in circumferential direction. Moreover, better thermal dissipation and conduction at brake disc rotor surface played a major influence on the stress. As a comparison, the maximum stress and strain of Al-MMCs brake disc was lower than that induced on the cast iron brake disc. (paper)

  16. Sex differences in lumbar degenerative disc disease.

    Science.gov (United States)

    Gautschi, Oliver P; Smoll, Nicolas R; Corniola, Marco V; Joswig, Holger; Schaller, Karl; Hildebrandt, Gerhard; Stienen, Martin N

    2016-06-01

    A growing number of studies focus on sex differences in the pre- and postoperative setting in patients with degenerative disc disease (DDD). The exact pathomechanism behind this phenomenon, however, remains unclear. The objective of this study was to investigate pre- and postoperative sex differences in patients with lumbar DDD. In a prospective two-center study, back and leg pain (Visual Analogue Scale (VAS)), functional disability (Oswestry Disability Index (ODI) and Roland-Morris Disability Index) and health-related quality of life (HRQoL) (EuroQol 5D and Short-Form (SF12)) were collected for patients scheduled for lumbar spine surgery. In addition to the subjective functional impairment (SFI), objective functional impairment (OFI) was estimated using age- and sex-adjusted cut-off values for the timed-up-and-go (TUG) test. The 6-week responder status was defined using minimally clinically important differences of the ODI, SF12 PCS, VAS back and leg pain in all patients. Six months and one year follow-up (FU) was available in n=127 and n=87 patients, respectively. The patient cohort comprised of n=214 patients (41.6% females). Preoperatively, female patients scored significantly worse on VAS back and leg pain, ODI and SF12 PCS (psex-related differences had resolved for SFI and OFI was similar as well (p=0.333). There were no sex differences in the mean improvement after 6 weeks for all measures of pain intensity, functional impairment and HRQoL (p>0.182). Male and female patients profited equally on measures of SFI and HRQoL up to six months and one year after surgery (p>0.091). Preoperatively, female patients scored worse in terms of SFI, while OFI was similar. Consecutively, OFI appears to be less prone to sex bias and may thus serve as a valuable surrogate-marker of disability. The disadvantageous preoperative SFI-status did not translate into worse postoperative results, as no sex differences were present at the 6-week, 6-months and 1-year follow

  17. Modal-Based Design Improvement of a Butterfly Valve Disc

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    Marius Draghiciu

    2017-11-01

    Full Text Available The dynamic behaviour control of a butterfly valve is important because, when one of the valve disc natural frequency is close to the frequency of vortex shedding, which appears when the valve is fully open or partially closed, resonance may appear and vibration with significant amplitudes is generated. This paper presents an example by how the design of a butterfly valve disc can be improved by using a modal analysis performed by means of the finite element method. For this purpose, the research reveals the way in which the natural frequencies of the disc can be modified by applying stiffening ribs or changing the dimensions, respective the position of these ribs.

  18. A physical process of the radial acceleration of disc galaxies

    Science.gov (United States)

    Wilhelm, Klaus; Dwivedi, Bhola N.

    2018-03-01

    An impact model of gravity designed to emulate Newton's law of gravitation is applied to the radial acceleration of disc galaxies. Based on this model (Wilhelm et al. 2013), the rotation velocity curves can be understood without the need to postulate any dark matter contribution. The increased acceleration in the plane of the disc is a consequence of multiple interactions of gravitons (called `quadrupoles' in the original paper) and the subsequent propagation in this plane and not in three-dimensional space. The concept provides a physical process that relates the fit parameter of the acceleration scale defined by McGaugh et al. (2016) to the mean free path length of gravitons in the discs of galaxies. It may also explain the gravitational interaction at low acceleration levels in MOdification of the Newtonian Dynamics (MOND, Milgrom 1983, 1994, 2015, 2016). Three examples are discussed in some detail: the spiral galaxies NGC 7814, NGC 6503 and M 33.

  19. Therapeutic surprise! Photodynamic therapy for cavernous haemangioma of the disc

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    Mahesh P Shanmugam

    2017-01-01

    Full Text Available Purpose: To report the response of cavernous haemangioma of the disc to PDT. Methods and Patients: A 32 years old lady presented to us with complaints of sudden onset of blurry vision in her right eye. What seemed initially as polypoidal choroidal vasculopathy turned out as cavernous haemangioma of the disc after pneumatic displacement of the sub-retinal haeme. She was treated with PDT as she was prone to recurrent haemorrhage from the lesion due to her low platelet count. Results: Complete regression of the cavernous haemangioma was noted as early as the second week itself and remained regressed for 4 months. Conclusion: PDT can be safe option for patients presenting with symptomatic cavernous haemangioma of the disc or retina.

  20. Control of senescence in rumex leaf discs by gibberellic Acid.

    Science.gov (United States)

    Goldthwaite, J J; Laetsch, W M

    1968-11-01

    The kinetics of chlorophyll and protein decomposition and the effect of gibberellic acid (GA) were examined in senescing leaf discs of Rumex crispus and R. obtusifolius. Loss of Rumex total chlorophyll proceeds at a slow rate for about 2 days followed by a period of rapid logarithmic decline. Chlorophyll b is lost at a slightly faster rate than chlorophyll a during senescence in discs as well as in situ. GA causes a complete cessation of net chlorophyll and protein degradation for several days in Rumex, in contrast to the incomplete senescence inhibition generally observed with cytokinins. GA is fully effective even when added at the middle of the logarithmic phase of chlorophyll loss. Senescence inhibition by GA is apparently gradually reversed upon GA removal. The cytokinins, kinetin and 6-benzylaminopurine, were also effective in Rumex leaf discs, indicating that the senescence retarding effect was not restricted to the gibberellins.

  1. Analysis of trace element in intervertebral disc by Atomic Absorption Spectrometry techniques in degenerative disc disease in the Polish population

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    Andrzej Nowakowski

    2015-05-01

    Full Text Available Objective. Although trace elements are regarded crucial and their content has been determined in number of tissue there are only few papers addressing this problem in intervertebral disc in humans. Most of the trace elements are important substrates of enzymes influencing metabolism and senescence process. Others are markers of environmental pollution. Therefore the aim of the research was to analyzed of the trace element content in the intervertebral disc, which may be a vital argument recognizing the background of degenerative changes to be the effect of the environment or metabolic factors. Materials and methods. Material consist of 18 intervertebral disc from 15 patients, acquired in surgical procedure of due to the degenerative disease with Atomic Absorption Spectrometry content of Al, Cd, Co, Pb, Cu, Ni, Mo, Mg, Zn was evaluated. Results. Only 4 of the trace elements were detected in all samples. The correlation analysis showed significant positive age correlation with Al and negative in case of Co. Among elements significant positive correlation was observed between Al/Pb, Co/Mo, Al/Mg, Al/Zn Pb/Zn and Mg/Zn. Negative correlation was observed in Al/Co, Cd/Mg, Co/Mg, Mo/Mg, Co/Zn and Mo/Zn. Conclusions. This study is the first to our knowledge that profiles the elements in intervertebral disc in patients with degenerative changes. We have confirmed significant differences between the trace element contents in intervertebral disc and other tissue. It can be ground for further investigation.

  2. Temporomandibular joint sounds and disc dislocations incidence after orotracheal intubation

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    Estela T Rodrigues

    2009-12-01

    Full Text Available Estela T Rodrigues1, Iván C Suazo2, Antonio S Guimarães31Centro de Pós Graduação em Odontologia São Leopoldo Mandic, Campinas, Brasil; 2Department of Morphology. Universidad de Talca, Talca, Chile; 3Centro de Pós Graduação em Odontologia São Leopoldo Mandic, Campinas, BrasilAbstract: The aim of this study was to analyze the temporomandibular joint (TMJ disc displacement and articular sounds incidence after orotracheal intubation. A prospective cohort study was conducted in the Hospital Universitário do Oeste do Paraná (HUOP, in Cascavel, Brazil. 100 patients (aged 14–74 years, mean 44 years, 34 male and 66 female, in need of surgical procedure with orotracheal intubation were evaluated. The anterior disc displacement with reduction incidence and the nonclassifiable sounds incidence by the Research Diagnostic Criteria Axis I was evaluated in all patients after orotracheal intubation. The patients was evaluated one day before and until two days after the procedure. Eight percent present with anterior disc displacement with reduction and 10% presented nonclassifiable sounds after the orotracheal intubation. There was no correlation of any kind regarding gender related influence in the incidence of disc dislocations (P = 0.2591 and TMJ sounds (P = 0.487. Although anterior disc dislocations and TMJ sounds after anesthetic with orotracheal intubation presented a low incidence (8%–10%, it is recommended that the evaluation of TMJ signs and symptoms be done before the anesthetic procedure to take care with susceptible patients manipulation.Keywords: orotracheal intubation, TMJ sounds, TMJ dislocations, TMJ disorders, disc displacement, surgical procedure

  3. The effect of environment on the structure of disc galaxies

    Science.gov (United States)

    Pranger, Florian; Trujillo, Ignacio; Kelvin, Lee S.; Cebrián, María

    2017-05-01

    We study the influence of environment on the structure of disc galaxies, using imfit to measure the g- and r-band structural parameters of the surface-brightness profiles for ˜700 low-redshift (z < 0.063) cluster and field disc galaxies with intermediate stellar mass (0.8 × 1010 M⊙ < M⋆ < 4 × 1010 M⊙) from the Sloan Digital Sky Survey, DR7. Based on this measurement, we assign each galaxy to a surface-brightness profile type (Type I ≡ single-exponential, Type II ≡ truncated, Type III ≡ antitruncated). In addition, we measure (g - r) rest frame colour for disc regions separated by the break radius. Cluster disc galaxies (at the same stellar mass) have redder (g - r) colour by ˜0.2 mag than field galaxies. This reddening is slightly more pronounced outside the break radius. Cluster disc galaxies also show larger global Sérsic-indices and are more compact than field discs, both by ˜15 per cent. This change is connected to a flattening of the (outer) surface-brightness profile of Type I and - more significantly - of Type III galaxies by ˜8 per cent and ˜16 per cent, respectively, in the cluster environment compared to the field. We find fractions of Type I, Type II and Type III of (6 ± 2) per cent, (66 ± 4) per cent and (29 ± 4) per cent in the field and (15_{-4}^{+7}) per cent, (56 ± 7) per cent and (29 ± 7) per cent in the cluster environment, respectively. We suggest that the larger abundance of Type I galaxies in clusters (matched by a corresponding decrease in the Type II fraction) could be the signature of a transition between Type II and Type I galaxies produced/enhanced by environment-driven mechanisms.

  4. A radiological study on lumbar disc herniation in Korean

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    Seol, Hae Young; Park, In Sik; Suh, Won Hyuk; Lee, Min Jae [Korea University College of Medicine, Seoul (Korea, Republic of)

    1979-12-15

    Among the patients operated because of lumbar disc herniation from January 1973 to May 1979 at Korea University Hospital, 154 cases were analyzed radiologically and the following conclusions were obtained. 1. The ratio of male to female was 1.96 : 1. 2. The incidences of single and multiple involvement were 74.7% and 25.3%. 3. Most frequent level of lumbar disc herniation was L4-5 interspace. 4. The incidences of left, central and bilateral defects were 45.45%, 33.76%, 12.33% and 8.44% respectively. 5. The incidences of spina bifida and transitional vertebra were 24.04% and 9.09% respectively. 6. The overall mean of the lumbosacral angle was 33.97 .deg. 7. The overall mean depth of the lumbar lordosis was 8.48 mm. 8. The ratio of the height of L4-5 interspace to the shorter anteroposterior diameter of L-5 body was obtained by authors' idea. The mean ratios of male and female patients of L4-5 disc herniation which had no evidence of the narrowing of L4-5 interspace on simple radiologic finding were 0.3042 and 0.3064 respectively. So the ratio had a little value in the diagnosis of L4-5 disc herniation on simple radiologic study. 9. Myelography had high diagnostic accuracy, and the majority of the pseudonegative finding on lumbar disc herniation myelographically was seen at L4-5 disc herniation.

  5. Disc volume reduction with percutaneous nucleoplasty in an animal model.

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    Richard Kasch

    Full Text Available STUDY DESIGN: We assessed volume following nucleoplasty disc decompression in lower lumbar spines from cadaveric pigs using 7.1Tesla magnetic resonance imaging (MRI. PURPOSE: To investigate coblation-induced volume reductions as a possible mechanism underlying nucleoplasty. METHODS: We assessed volume following nucleoplastic disc decompression in pig spines using 7.1-Tesla MRI. Volumetry was performed in lumbar discs of 21 postmortem pigs. A preoperative image data set was obtained, volume was determined, and either disc decompression or placebo therapy was performed in a randomized manner. Group 1 (nucleoplasty group was treated according to the usual nucleoplasty protocol with coblation current applied to 6 channels for 10 seconds each in an application field of 360°; in group 2 (placebo group the same procedure was performed but without coblation current. After the procedure, a second data set was generated and volumes calculated and matched with the preoperative measurements in a blinded manner. To analyze the effectiveness of nucleoplasty, volumes between treatment and placebo groups were compared. RESULTS: The average preoperative nucleus volume was 0.994 ml (SD: 0.298 ml. In the nucleoplasty group (n = 21 volume was reduced by an average of 0.087 ml (SD: 0.110 ml or 7.14%. In the placebo group (n = 21 volume was increased by an average of 0.075 ml (SD: 0.075 ml or 8.94%. The average nucleoplasty-induced volume reduction was 0.162 ml (SD: 0.124 ml or 16.08%. Volume reduction in lumbar discs was significant in favor of the nucleoplasty group (p<0.0001. CONCLUSIONS: Our study demonstrates that nucleoplasty has a volume-reducing effect on the lumbar nucleus pulposus in an animal model. Furthermore, we show the volume reduction to be a coblation effect of nucleoplasty in porcine discs.

  6. Lumbosacral sagittal alignment in association to intervertebral disc diseases.

    Science.gov (United States)

    Habibi, Zohreh; Maleki, Farid; Meybodi, Ali Tayebi; Mahdavi, Ali; Saberi, Hooshang

    2014-12-01

    A cross-sectional case-control study was designed to compare the sagittal alignment of lumbosacral regions in two groups of patients suffering from low back pain, one with intervertebral disc pathologies and one without. To evaluate the correlation between lumbosacral sagittal alignment and disc degeneration. Changes in lumbar lordosis and pelvic parameters in degenerative disc lesions have been assessed in few studies. Overall, patients with discopathy were shown to have lower lumbar lordosis and more vertical sacral profiles. From patients with intractable low back pain undergoing lumbosacral magnetic resonance imaging, 50 subjects with disc degeneration and 50 controls with normal scans were consecutively enrolled. A method was defined with anterior tangent-lines going through anterior bodies of L1 and S1 to measure global lumbosacral angle, incorporating both lumbar lordosis and sacral slope. Global lumbosacral angle using the proposed method and lumbar lordosis using Cobb's method were measured in both groups. Lumbar lordosis based on Cobb's method was lower in group with discopathy (20°-67°; mean, 40.48°±9.89°) than control group (30°-62°; mean, 44.96°±7.68°), although it was not statistically significant. The proposed global lumbosacral angle in subject group (53°-103°; mean, 76.5°±11.018°) was less than control group (52°-101°; mean, 80.18°±9.95°), with the difference being statistically significant (p=0.002). Patients with intervertebral disc lesions seem to have more straightened lumbosacral profiles, but it has not been proven which comes first: disc degeneration or changes in sagittal alignment. Finding an answer to this dilemma demands more comprehensive long-term prospective studies.

  7. The Dusty Disc of NGC 247

    Science.gov (United States)

    2011-03-01

    This image of NGC 247, taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile, reveals the fine details of this highly inclined spiral galaxy and its rich backdrop. Astronomers say this highly tilted orientation, when viewed from Earth, explains why the distance to this prominent galaxy was previously overestimated. The spiral galaxy NGC 247 is one of the closest spiral galaxies of the southern sky. In this new view from the Wide Field Imager on the MPG/ESO 2.2-metre telescope in Chile large numbers of the galaxy's component stars are clearly resolved and many glowing pink clouds of hydrogen, marking regions of active star formation, can be made out in the loose and ragged spiral arms. NGC 247 is part of the Sculptor Group, a collection of galaxies associated with the Sculptor Galaxy (NGC 253, also shown in eso0902 and eso1025). This is the nearest group of galaxies to our Local Group, which includes the Milky Way, but putting a precise value on such celestial distances is inherently difficult. To measure the distance from the Earth to a nearby galaxy, astronomers have to rely on a type of variable star called a Cepheid to act as a distance marker. Cepheids are very luminous stars, whose brightness varies at regular intervals. The time taken for the star to brighten and fade can be plugged into a simple mathematical relation that gives its intrinsic brightness. When compared with the measured brightness this gives the distance. However, this method isn't foolproof, as astronomers think this period-luminosity relationship depends on the composition of the Cepheid. Another problem arises from the fact that some of the light from a Cepheid may be absorbed by dust en route to Earth, making it appear fainter, and therefore further away than it really is. This is a particular problem for NGC 247 with its highly inclined orientation, as the line of sight to the Cepheids passes through the galaxy's dusty disc. However, a

  8. Disc Battery - An Unusual Vaginal Foreign Body in a Child.

    Science.gov (United States)

    Khan, Yousuf Aziz; Mahmood, Mansoor; Taqi, Esmaeel

    2016-01-01

    Disc battery ingestion and esophageal injury is well-known in children. Insertion of a disc/lithium battery into body's natural orifices is rarely reported. We present a case of self-insertion of a lithium battery into the vagina by a 2 ½ year old female. Vaginoscopy was performed and the battery was retrieved which had corroded and caused vaginal ulceration. Post-operative outcome was favorable. Treating physicians must be aware of the hazardous effects of insertion of lithium batteries as it may cause significant damage in a short period.

  9. A homopolar disc dynamo experiment with liquid metal contacts

    OpenAIRE

    Avalos-Zúñiga, R. A.; Priede, J.; Bello-Morales, C. E.

    2017-01-01

    We present experimental results of a homopolar disc dynamo constructed at CICATA-Quer\\'etaro in Mexico. The device consists of a flat, multi-arm spiral coil which is placed above a fast-spinning metal disc and connected to the latter by sliding liquid-metal electrical contacts. Theoretically, self-excitation of the magnetic field is expected at the critical magnetic Reynolds number Rm~45, which corresponds to a critical rotation rate of about 10 Hz. We measured the magnetic field above the di...

  10. Diagnostic accuracy of magnetic resonance imaging of lumbar disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Takashi; Nakamura, Takafumi; Kikuchi, Taro; Watanabe, Hiroyuki; Takagi, Katsumasa; Yoshizumi, Kazuhiro; Katahira, Kazuhiro [Kumamoto Univ. (Japan). School of Medicine

    2000-03-01

    We studied the accuracy of MRI in lumbar disc herniation, comparing the results with the operative findings in the assessment of the rupture of the posterior longitudinal ligament (PLL), and type of herniation. The MRI findings in 47 subjects who were operated on for lumbar disc herniation were retrospectively studied. The accuracy rate was 75.2% for the rupture of the PLL and 40.4% for the type of herniation respectively. It was hard to differentiate subligamentous extrusion from transligamentous extrusion on MRI. (author)

  11. Congenital maldevelopment of intervertebral disc simulating a neurofibroma

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, M.; Malik, A.; Mishra, N.K.; Chandra, S.; Gaikwad, S.B. [Department of Neuroradiology, All India Institute of Medical Sciences, New Delhi (India); Jain, K. [Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi (India)

    1998-07-01

    Intervertebral disc herniation is a common cause of radiculopathy and myelopathy in adulthood. It is an uncommon tumor mimic. We report on an extradural disc associated with an osseous defect ostensibly caused by pressure erosion and appearing as a neural tumor. It showed homogeneous enhancement on a contrast-enhanced MR examination, leading to an erroneous diagnosis of nerve sheath tumor. An attempt has been made to explain the likely mechanism of formation accounting for the imaging appearances, along with a review of the literature. (orig.) With 3 figs., 9 refs.

  12. [Principles of intervertebral disc assessment in private accident insurance].

    Science.gov (United States)

    Steinmetz, M; Dittrich, V; Röser, K

    2015-09-01

    Due to the spread of intervertebral disc degeneration, insurance companies and experts are regularly confronted with related assessments of insured persons under their private accident insurance. These claims pose a particular challenge for experts, since, in addition to the clinical assessment of the facts, extensive knowledge of general accident insurance conditions, case law and current study findings is required. Each case can only be properly assessed through simultaneous consideration of both the medical and legal facts. These guidelines serve as the basis for experts and claims.managers with respect to the appropriate individual factual assessment of intervertebral disc degeneration in private accident insurance.

  13. Is tomography of intervertebral disc calcification useful in children?

    International Nuclear Information System (INIS)

    Ginalski, J.M.; Landry, M.; Gudinchet, F.; Schnyder, P.

    1992-01-01

    In the past ten years, we have found cervical intervertebral disc calcification in three children on plain films of the cervical spine made because of cervical pain. In each case, we required further radiological investigations, antero-posterior and lateral linear tomography for two children and an axial computed tomography for one child. In each case, tomography revealed no supplementary useful information. On retrospect, we think that these examinations caused unnecessary irradiation and that they should only be carried out in the rare circumstances when disc calcification is associated with neurological symptoms. (orig.)

  14. Heterotopic ossification associated with myelopathy following cervical disc prosthesis implantation.

    Science.gov (United States)

    Wenger, Markus; Markwalder, Thomas-Marc

    2016-04-01

    This case report presents a 37-year-old man with clinical signs of myelopathy almost 9 years after implantation of a Bryan disc prosthesis (Medtronic Sofamor Danek, Memphis, TN, USA) for C5/C6 soft disc herniation. As demonstrated on MRI and CT scan, spinal cord compression was caused by bony spurs due to heterotopic ossification posterior to the still moving prosthesis. The device, as well as the ectopic bone deposits, had to be removed because of myelopathy and its imminent aggravation. Conversion to anterior spondylodesis was performed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Residual stresses in a cast iron automotive brake disc rotor

    Science.gov (United States)

    Ripley, Maurice I.; Kirstein, Oliver

    2006-11-01

    Runout, and consequent juddering and pulsation through the brake pedal, is a multi-million dollar per year warranty problem for car manufacturers. There is some suspicion that the runout can be caused by relaxation of residual casting stresses when the disc is overheated during severe-braking episodes. We report here neutron-diffraction measurements of the levels and distribution of residual strains in a used cast iron brake disc rotor. The difficulties of measuring stresses in grey cast iron are outlined and three-dimensional residual-strain distributions are presented and their possible effects discussed.

  16. Remote punching of discs from radioactive samples for electron microscopy

    International Nuclear Information System (INIS)

    Rowe, J.; Madden, P.K.; Callen, V.M.

    1980-02-01

    A 'unidisc hand-operated press' has been modified for in-cave cutting of 3 mm diameter discs, destined for examination in the transmission electron microscope. No equivalent facility is available commercially. The modified punch is mechanically stable, compact in size for posting and easy to use since sample punching is controlled from a hand pump outside the cave. Discs may be cut from tested and untested strip tensile samples. The specially built sample locating jig may be interchanged to accept other sample geometries. (author)

  17. Residual stresses in a cast iron automotive brake disc rotor

    International Nuclear Information System (INIS)

    Ripley, Maurice I.; Kirstein, Oliver

    2006-01-01

    Runout, and consequent juddering and pulsation through the brake pedal, is a multi-million dollar per year warranty problem for car manufacturers. There is some suspicion that the runout can be caused by relaxation of residual casting stresses when the disc is overheated during severe-braking episodes. We report here neutron-diffraction measurements of the levels and distribution of residual strains in a used cast iron brake disc rotor. The difficulties of measuring stresses in grey cast iron are outlined and three-dimensional residual-strain distributions are presented and their possible effects discussed

  18. Early diagnosis of disc-space infection using gallium-67

    International Nuclear Information System (INIS)

    Norris, S.; Ehrlich, M.G.; Keim, D.E.; Guiterman, H.; McKusick, K.A.

    1978-01-01

    A 4-year-old boy had had progressive central lumbar pain and hamstring spasm. He had a normal lumbar-spine x-ray except for minimal L-5, S1 spondylolysis, but gave an abnormal gallium-67 scan in the region of the low lumbar spine. Eight weeks following intensive antibiotic therapy, confirmation of the diagnosis of disc-space infection was established by roentgenographic studies that demonstrated narrowing of the L 4 to 5 intervertebral disc space. A technetium-99m diphosphonate bone scan, performed concurrently with the gallium-67 study, was normal

  19. Human and bovine spinal disc mechanics subsequent to trypsin injection

    Directory of Open Access Journals (Sweden)

    Jeremy Alsup

    2017-10-01

    The Translational Potential of this Article: Preclinical testing of novel spinal devices is essential to the design validation and regulatory processes, but current testing techniques rely on cadaveric testing of primarily older spines with essentially random amounts of disc degeneration. The present work investigates the viability of using trypsin injections to create a more uniform preclinical model of disc degeneration from a mechanics perspective, for the purpose of testing spinal devices. Such a model would facilitate translation of new spinal technologies to clinical practice.

  20. Failure analysis of clutch disc in a two-ton truck; Análisis de falla del disco de embrague de un camión de 2 ton

    Directory of Open Access Journals (Sweden)

    Diego Leon Perea Salcedo

    2013-06-01

    Full Text Available This article presents the failure analysis of a clutch disc in a two-ton truck. The failure part was made of high-carbon steel for springs. Although the failure surface was very thin and difficult to interpret, the fracture surface examination revealed chevron marks and the presence of faint beach marks. The failure parts were made of hardened 1070 carbon steel. The cushioning plate experienced shear and bending alternating stress. The end failure is caused by shock load.

  1. Failure analysis of clutch disc in a two-ton truck; Análisis de falla del disco de embrague de un camión de 2 ton

    OpenAIRE

    Diego Leon Perea Salcedo

    2013-01-01

    This article presents the failure analysis of a clutch disc in a two-ton truck. The failure part was made of high-carbon steel for springs. Although the failure surface was very thin and difficult to interpret, the fracture surface examination revealed chevron marks and the presence of faint beach marks. The failure parts were made of hardened 1070 carbon steel. The cushioning plate experienced shear and bending alternating stress. The end failure is caused by shock load.

  2. Correlation of plain radiographic and lumbar myelographic findings with surgical findings in thoracolumbar disc disease

    International Nuclear Information System (INIS)

    Oldby, N.J.; Dyce, J.; Houlton, J.E.F.

    1994-01-01

    The results of a prospective study to compare the plain radiographic and lumbar myelographic findings with the surgical findings in 70 cases of suspected thoracolumbar disc protrusion in the dog are reported. The aim was to assess the relative accuracy of disc lesion localisation using plain and contrast radiography. From the plain radiographs, the affected disc space was correctly identified in 40 cases (57.1 per cent), and incorrectly identified in seven. More than one site was identified in 11; in eight of these dogs, the affected disc space was strongly suspected. It was not possible to identify an affected disc in 12 cases. The site of disc protrusion was accurately identified by myelography in 60 dogs (85.7 per cent). In four dogs, myelography was helpful in identifying an adjacent disc and, in a further two, cord swelling was found at surgery. In one dog, neither disc material nor cord swelling was identified. Three myelograms were non-diagnostic

  3. File list: ALL.Lar.10.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  4. File list: ALL.Lar.50.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  5. File list: ALL.Lar.05.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  6. File list: ALL.Lar.20.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Lar.20.AllAg.Dorsal_mesothoracic_disc dm3 All antigens Larvae Dorsal mesothorac...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Lar.20.AllAg.Dorsal_mesothoracic_disc.bed ...

  7. Evaluation of Squeal Noise from the WMATA Transit Car Disc Brake System : A Preliminary Investigation

    Science.gov (United States)

    1981-03-01

    The Washington Metropolitan Area Transit Authority (WMATA) rail transit car design adopted the use of disc brakes as the primary friction braking system. Unfortunately, while disc brakes are more efficient than the traditional tread brake designs, th...

  8. COMPARISON OF THERMOELASTIC RESULTS IN TWO TYPES OF FUNCTIONALLY GRADED BRAKE DISCS

    Directory of Open Access Journals (Sweden)

    Z.N. Ismarrubie

    2012-06-01

    Full Text Available A thermoelastic simulation of functionally graded (FG brake discs is performed using finite element (FE ANSYS. The material properties of two types of FG brake discs are assumed to vary in both radial and thickness directions according to a power law distribution. The brake discs are in contact with one hollow pure pad disc. Dry contact friction is considered as the heat source. The proper thicknesses of pad discs are found to have full-contact status. The behaviour of the thermoelastic results for thickness and radial FG brake discs are compared. The results show that the behaviour of temperature and vertical displacement in these two types of FG brake discs are the same. However, the variations of radial displacement for different grading indices are not the same. The behaviour of other results are quite similar. Thus, it can be concluded that the variation direction of material properties in FG brake discs can affect the results.

  9. Trapping of low-mass planets outside the truncated inner edges of protoplanetary discs

    Science.gov (United States)

    Miranda, Ryan; Lai, Dong

    2018-02-01

    We investigate the migration of a low-mass (≲10 M⊕) planet near the inner edge of a protoplanetary disc using two-dimensional viscous hydrodynamics simulations. We employ an inner boundary condition representing the truncation of the disc at the stellar corotation radius. As described by Tsang, wave reflection at the inner disc boundary modifies the Type I migration torque on the planet, allowing migration to be halted before the planet reaches the inner edge of the disc. For low-viscosity discs (α ≲ 10-3), planets may be trapped with semi-major axes as large as three to five times the inner disc radius. In general, planets are trapped closer to the inner edge as either the planet mass or the disc viscosity parameter α increases, and farther from the inner edge as the disc thickness is increased. This planet trapping mechanism may impact the formation and migration history of close-in compact multiplanet systems.

  10. Three-dimensional analysis of volumetric changes in herniated discs of the lumbar spine: does spontaneous resorption of herniated discs always occur?

    Science.gov (United States)

    Seo, Jun-Yeong; Roh, Young-Ho; Kim, Young-Hoon; Ha, Kee-Yong

    2016-05-01

    To investigate volumetric changes in lumbar disc herniation (LDH) using three-dimensional measurements obtained by magnetic resonance imaging (MRI) and to identify possible factors affecting such changes. Between January 2004 and December 2011, 43 patients who underwent conservative treatment for LDH were enrolled. In all, 56 disc levels were investigated. MRI was performed on two or more occasions (minimally, at the initial visit and 6 months later). The volume of each herniated disc was determined. For each patient, disc migration, morphology, initial LDH size, and clinical outcome were evaluated. The mean volumes of herniated discs at the initial and follow-up visits were 1,304.57 ± 837.99 and 993.84 ± 610.04 mm(3), respectively. The mean change in volume from the initial to the follow-up visit was 310.73 ± 743.60 mm(3). Volumes decreased at 35 disc levels and increased at 21 levels. The disc containment, the extent of LDH, the initial size of the herniated disc, and the degree of intactness of the posterior longitudinal ligament were significantly correlated with disc resorption and an increase in disc volume (p = 0.01, p = 0.018, p = 0.001, and p disc volumetric change and clinical outcome. We observed that LDH is a dynamic disease and that a herniated disc is not always spontaneously resorbed, in contrast to what has been reported previously. Alleviation of clinical symptoms can be achieved via conservative treatment even if the volume of the herniated disc changes. Spinal surgeons should not only present an option of initial non-surgical treatment to LDH patients but should also inform them that the LDH may change in size during daily activity or exercise.

  11. The Specific Sagittal Magnetic Resonance Imaging of Intradural Extra-Arachnoid Lumbar Disc Herniation

    OpenAIRE

    Sasaji, Tatsuro; Horaguchi, Kiyoshi; Yamada, Noboru; Iwai, Kazuo

    2012-01-01

    Intradural extra-arachnoid lumbar disc herniation is a rare disease. Few MRI findings have been reported. We experienced an intradural extra-arachnoid lumbar disc herniation. We reviewed the preoperative MRI findings. Lumbar spine T2-weighted sagittal MRI showed that one line of the ventral dura was divided into two by a disc herniation. We speculated that the two lines comprised the dura and arachnoid and that a disc herniation existed between them. We believe that division of the ventral du...

  12. Mechanical deformation and glycosaminoglycan content changes in a rabbit annular puncture disc degeneration model.

    Science.gov (United States)

    Chan, Deva D; Khan, Safdar N; Ye, Xiaojing; Curtiss, Shane B; Gupta, Munish C; Klineberg, Eric O; Neu, Corey P

    2011-08-15

    Evaluation of degenerated intervertebral discs from a rabbit annular puncture model by using specialized magnetic resonance imaging (MRI) techniques, including displacement encoding with stimulated echoes and a fast-spin echo (DENSE-FSE) acquisition and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). To evaluate a rabbit disc degeneration model by using various MRI techniques. To determine the displacements and strains, spin-lattice relaxation time (T1), and glycosaminoglycan (GAG) distribution of degenerated discs as compared to normal and adjacent level discs. Annular puncture of the intervertebral disc produces disc degeneration in rabbits. DENSE-FSE has been previously demonstrated in articular cartilage for the measurement of soft tissue displacements and strains. MRI also can measure the T1 of tissue, and dGEMRIC can quantify GAG concentration in cartilage. METHODS.: In eight New Zealand white rabbits, the annulus fibrosis of a lumbar disc was punctured. After 4 weeks, the punctured and cranially adjacent motion segments were isolated for MRI and histology. MRI was used to estimate the disc volume and map T1. DENSE-FSE was used to determine displacements for the estimation of strains. dGEMRIC was then used to determine GAG distributions. Histology and standard MRI indicated degeneration in punctured discs. Disc volume increased significantly at 4 weeks after the puncture. Displacement of the nucleus pulposus was distinct from that of the annulus fibrosis in most untreated discs but not in punctured discs. T1 was significantly higher and GAG concentration significantly lower in punctured discs compared with untreated adjacent level discs. Noninvasive and quantitative MRI techniques can be used to evaluate the mechanical and biochemical changes that occur with animal models of disc degeneration. DENSE-FSE, dGEMRIC, and similar techniques have potential for evaluating the progression of disc degeneration and the efficacy of treatments.

  13. Intervertebral disc regeneration or repair with biomaterials and stem cell therapy - feasible or fiction?

    OpenAIRE

    Chan Samantha; Gantenbein-Ritter Benjamin

    2012-01-01

    The “gold standard” for treatment of intervertebral disc herniations and degenerated discs is still spinal fusion corresponding to the saying “no disc – no pain”. Mechanical prostheses which are currently implanted do only have medium outcome success and have relatively high re operation rates. Here we discuss some of the biological intervertebral disc replacement approaches which can be subdivided into at least two classes in accordance to the two different tissue types the nucleus pulposus ...

  14. Detection of residual disc hernia material and confirmation of nerve root decompression at lumbar disc herniation surgery by intraoperative ultrasound.

    Science.gov (United States)

    Aoyama, Takeshi; Hida, Kazutoshi; Akino, Minoru; Yano, Shunsuke; Iwasaki, Yoshinobu

    2009-06-01

    The aim of lumbar disc herniation surgery is the removal of herniated disc material (HDM) and complete decompression of the nerve root. As some patients present with residual HDM, we examined the ability of intraoperative ultrasound (IOUS) to detect this material. Between February 2006 and June 2007, we used IOUS in 30 patients undergoing surgery for lumbar disc herniation. They were 17 men and 13 women; their ages ranged from 22 to 63 y (mean 44.0 y). The level surgically addressed was L3/4 in 1, L4/5 in 14 and L5/S1 in 15 patients; they were operated in the prone position. After placing a 3-4 cm midline skin incision, partial hemi-semilaminotomy was performed. HDM was removed through a bone window; a surgical microscope was used during the operation. After removal was judged as adequate, IOUS was performed; 17 patients also underwent IOUS before removal of the herniated disc. For the acquisition of IOUS images, we used LOGIQ 9 and 8c microconvex probes (GE Healthcare, Wauwatosa, WI, USA). The normal anatomical structures were well visualized. HDM was iso- to hyperechoic compared with normal nerve tissue. In three of 17 patients, the dural sac and nerve root could not be distinguished from HDM before removal, although in all 30, the decompressed dural sac, intradural cauda equina and nerve root were well visualized. We posit that the echogenicity of nerve tissue was raised due to compression, rendering it similar to that of the herniated disc. In two patients, IOUS detected residual disc material; the surgical procedure was resumed and sufficient removal was accomplished. IOUS monitoring is safe, convenient and inexpensive. It is also highly useful for the detection of residual HDM and the confirmation of adequate nerve root decompression.

  15. Optical thin film deposition

    International Nuclear Information System (INIS)

    Macleod, H.A.

    1979-01-01

    The potential usefulness in the production of optical thin-film coatings of some of the processes for thin film deposition which can be classified under the heading of ion-assisted techniques is examined. Thermal evaporation is the process which is virtually universally used for this purpose and which has been developed to a stage where performance is in almost all respects high. Areas where further improvements would be of value, and the possibility that ion-assisted deposition might lead to such improvements, are discussed. (author)

  16. Thin Film Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K.

    1998-11-19

    The motivation to develop thin film technologies dates back to the inception of photovoltaics. It is an idea based on achieving truly low-cost photovoltaics appropriate for mass production and energy significant markets. The key to the idea is the use of pennies worth of active materials. Since sunlight carries relatively little energy in comparison with combustion-based energy sources, photovoltaic (PV) modules must be cheap to produce energy that can be competitive. Thin films are presumed to be the answer to that low-cost requirement. But how cheap do they have to be? The following is an oversimplified analysis that allows some insight into this question.

  17. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    Jayakumar, S.; Kannan, M.D.; Prasanna, S.

    2012-01-01

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  18. Shear Thinning in Xenon

    Science.gov (United States)

    Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

    2009-01-01

    We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

  19. Experience in Nonsurgical Treatment of Patients with Intervertebral Disc Protrusions and Herniated Discs Combined with Lumbar Instability

    Directory of Open Access Journals (Sweden)

    O.Ye. Pashkov

    2014-10-01

    Full Text Available An analysis of the data from 40 patients with instability and herniated disc in the lumbar spine has been carried out. The short-term (1 month and long-term (1.5 years results of conservative treatment were analyzed, and also the nature and characteristics of their course in the early and late periods were examined. Combined use of manual therapy and traction is not allowed as a method of conservative treatment for disc herniation associated with instability. Rehabilitation of the patient (targeted recovery of reliability of the spine functioning under physiological, common and industrial loads is advisable.

  20. Posterior transdural discectomy : a new approach for the removal of a central thoracic disc herniation

    NARCIS (Netherlands)

    Coppes, Maarten H; Bakker, Nicolaas A; Metzemaekers, Jan D M; Groen, Rob J M

    BACKGROUND: The optimal surgical approach for thoracic disc herniation remains a matter of debate, especially for central disc herniation. In this paper, we present a new technique to remove central thoracic disc herniation, the posterior transdural approach, and report a series of 13 cases operated

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  7. File list: Oth.Lar.20.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Lar.20.AllAg.Dorsal_mesothoracic_disc dm3 TFs and others Larvae Dorsal mesothor...acic disc SRX151957,SRX151959,SRX151958,SRX151956 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Lar.20.AllAg.Dorsal_mesothoracic_disc.bed ...

  8. File list: Unc.Lar.05.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Lar.05.AllAg.Dorsal_mesothoracic_disc dm3 Unclassified Larvae Dorsal mesothorac...ic disc http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Lar.05.AllAg.Dorsal_mesothoracic_disc.bed ...

  9. File list: DNS.Lar.50.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Lar.50.AllAg.Dorsal_mesothoracic_disc dm3 DNase-seq Larvae Dorsal mesothoracic ...disc http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Lar.50.AllAg.Dorsal_mesothoracic_disc.bed ...

  10. File list: His.Lar.50.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Lar.50.AllAg.Dorsal_mesothoracic_disc dm3 Histone Larvae Dorsal mesothoracic di...sc http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Lar.50.AllAg.Dorsal_mesothoracic_disc.bed ...

  11. File list: Oth.Lar.05.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Lar.05.AllAg.Dorsal_mesothoracic_disc dm3 TFs and others Larvae Dorsal mesothor...acic disc SRX151957,SRX151958,SRX151959,SRX151956 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Lar.05.AllAg.Dorsal_mesothoracic_disc.bed ...

  12. File list: Unc.Lar.50.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Lar.50.AllAg.Dorsal_mesothoracic_disc dm3 Unclassified Larvae Dorsal mesothorac...ic disc http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Lar.50.AllAg.Dorsal_mesothoracic_disc.bed ...

  13. File list: DNS.Lar.10.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Lar.10.AllAg.Dorsal_mesothoracic_disc dm3 DNase-seq Larvae Dorsal mesothoracic ...disc http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Lar.10.AllAg.Dorsal_mesothoracic_disc.bed ...

  14. File list: Oth.Lar.10.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Lar.10.AllAg.Dorsal_mesothoracic_disc dm3 TFs and others Larvae Dorsal mesothor...acic disc SRX151957,SRX151958,SRX151959,SRX151956 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Lar.10.AllAg.Dorsal_mesothoracic_disc.bed ...

  15. File list: Unc.Lar.10.AllAg.Dorsal_mesothoracic_disc [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Lar.10.AllAg.Dorsal_mesothoracic_disc dm3 Unclassified Larvae Dorsal mesothorac...ic disc http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Lar.10.AllAg.Dorsal_mesothoracic_disc.bed ...

  16. Association between visual degeneration of intervertebral discs and the apparent diffusion coefficient.

    Science.gov (United States)

    Niinimäki, Jaakko; Korkiakoski, Arto; Ojala, Outi; Karppinen, Jaro; Ruohonen, Jyrki; Haapea, Marianne; Korpelainen, Raija; Natri, Antero; Tervonen, Osmo

    2009-06-01

    The value of apparent diffusion coefficient (ADC) measurements in intervertebral disc has been studied because ADC provides an estimate of free diffusion of unbound water and could be used as a quantitative tool to estimate degenerative changes. However, the challenging nature of diffusion imaging of spine and limited numbers of subjects in earlier studies has produced contradictory findings. We aimed to determine the relation between ADC and visual degenerative changes in lumbar intervertebral discs in a sufficiently large homogeneous study group. Lumbar spines of 228 volunteer middle-aged men were MR imaged at 1.5 T including anatomic and diffusion-weighted imaging. ADC values, T2 signal intensity and height, and width of the three lowest lumbar intervertebral discs were measured and disc degeneration visually graded. The calculated average ADC of 530 measured discs was 2.01 x 10(-3) mm(2)/s+/-0.29 (+/-S.D.). The reduction in ADC between visually normal and moderately degenerated discs was 4%. Severely degenerated discs showed 5% larger ADC values than normal discs, presumably due to free water in cracks and fissures of those discs. T2 signal intensity of the disc was significantly correlated with the ADC values, whereas other measured parameters did not show correlation. There was no evident difference in ADC between the studied anatomic lumbar levels. Because there is considerable overlap between ADC values of normal and degenerated discs, we conclude that ADC measurements of intervertebral discs, at least with current technology, have limited clinical value.

  17. Investigations into the Mechanical Properties and Microstructural Behavior of Foreign and Locally Fabricated Brake Disc

    Directory of Open Access Journals (Sweden)

    Basil Olufemi Akinnuli

    2017-11-01

    Full Text Available The present work reports investigations on mechanical and microstructural properties of foreign and locally fabricated brake disc. From safety point of view, brake disc is a crucial component of the braking system. Foreign brake disc (FBD are known for their long life span and better mechanical properties under service condition. However, locally fabricated brake disc (LFBD may possess similar or better mechanical properties than the foreign one. Therefore, the need to investigate their mechanical properties in order to determine which brake disc has better mechanical properties under the same service condition. It was observed that a high machinability index occurs in the locally fabricated brake disc as compared with the foreign brake disc, noticeable in the softness and weak graphite flakes formation in the matrix. Higher resistance to indentation was noticeable in the foreign brake disc as compared to the locally fabricated disc. The locally fabricated brake disc however, witnesses about 22% reduction in toughness compared to the foreign brake disc. An offshoot from this research will enhance the choice of material selection in the manufacturing of brake disc and assurance of locally made spare parts at affordable prices, and the provision of employment opportunities by establishing spare-parts production and allied industries

  18. Ensuring long-term reliability of the data storage on optical disc

    Science.gov (United States)

    Chen, Ken; Pan, Longfa; Xu, Bin; Liu, Wei

    2008-12-01

    "Quality requirements and handling regulation of archival optical disc for electronic records filing" is released by The State Archives Administration of the People's Republic of China (SAAC) on its network in March 2007. This document established a complete operative managing process for optical disc data storage in archives departments. The quality requirements of the optical disc used in archives departments are stipulated. Quality check of the recorded disc before filing is considered to be necessary and the threshold of the parameter of the qualified filing disc is set down. The handling regulations for the staffs in the archives departments are described. Recommended environment conditions of the disc preservation, recording, accessing and testing are presented. The block error rate of the disc is selected as main monitoring parameter of the lifetime of the filing disc and three classes pre-alarm lines are created for marking of different quality check intervals. The strategy of monitoring the variation of the error rate curve of the filing discs and moving the data to a new disc or a new media when the error rate of the disc reaches the third class pre-alarm line will effectively guarantee the data migration before permanent loss. Only when every step of the procedure is strictly implemented, it is believed that long-term reliability of the data storage on optical disc for archives departments can be effectively ensured.

  19. DNA synthesis in the imaginal wing discs of the American bollworm ...

    Indian Academy of Sciences (India)

    Unknown

    Care was taken during dissection as the fat body and muscles tend to obscure the imaginal discs. Imaginal discs were distinctly seen under stereo bino- cular microscope, from one-day old final-instar larvae of. H. armigera. 2.3 Incubation. A pair of mesothoracic wing discs was excised in lepidopteran saline (Bindokas and ...

  20. The use of birefringence for predicting the stiffness of injection molded polycarbonate discs

    NARCIS (Netherlands)

    Neves, N.M.; Pouzada, A.S.; Voerman, J.H.D.; Powell, P.C.

    1998-01-01

    Polycarbonate discs were injection molded with different sets of molding conditions. The parameters studied were the flow rate, melt- and mold-temperature. The discs were subjected to three point support flexural tests. Those tests are specially intended for injection molded discs because of their