1,246 research outputs found

    Degenerative Lumbar Stenosis: Update

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    We present a literature review of the diagnosis and treatment of acquired lumbar spinal stenosis (LS), with a brief description of new surgical techniques. LS is the most common cause of spinal surgery in individuals older than 65 years of age. Neurogenic claudication and radiculopathy result from compression of the cauda equina and lumbosacral nerve roots by degenerated spinal elements. Surgical decompression is a well established treatment for patients with refractory, or moderate to severe clinical symptoms. However, the variety of surgical options is vast. New techniques have been developed with the goal of increasing long term functional outcomes. In this article we review lumbar decompression and fusion as treatment options for LS but also present other recent developments. 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Philadelphia: WB SaundersHackenberg, L., Halm, H., Bullmann, V., Vieth, V., Schneider, M., Liljenqvist, U., Transforaminal lumbar interbody fusion: A safe technique with satisfactory three to five year results (2005) European Spine Journal, 14 (6), pp. 551-558. , DOI 10.1007/s00586-004-0830-1Pavlov, P.W., Meijers, H., Van Limbeek, J., Jacobs, W.C.H., Lemmens, J.A.M., Obradov-Rajic, M., De Kleuver, M., Good outcome and restoration of lordosis after anterior lumbar interbody fusion with additional posterior fixation (2004) Spine, 29 (17), pp. 1893-1899. , DOI 10.1097/01.brs.0000137067.68630.70Periasamy, K., Shah, K., Wheelwright, E.F., Posterior lumbar interbody fusion using cages, combined with instrumented posterolateral fusion: A study of 75 cases (2008) Acta Orthop Belg, 74, pp. 240-248Salehi, S.A., Tawk, R., Ganju, A., Lamarca, F., Liu, J.C., Ondra, S.L., Sonntag, V.K.H., Frempong-Boadu, A.K., Transforaminal Lumbar Interbody Fusion: Surgical Technique and Results in 24 Patients (2004) Neurosurgery, 54 (2), pp. 368-374Hsieh, P.C., Koski, T.R., O'Shaughnessy, B.A., Anterior lumbar interbody fusion in comparison with transforaminal lumbar interbody fusion: Implications for the restoration of foraminal height, local disc angle, lumbar lordosis, and sagittal balance (2007) J Neurosurg Spine, 7, pp. 379-386Ozgur, B.M., Aryan, H.E., Pimenta, L., Taylor, W.R., Extreme Lateral Interbody Fusion (XLIF): A novel surgical technique for anterior lumbar interbody fusion (2006) Spine J, 6, pp. 435-443Ahlmann, E., Patzakis, M., Roidis, N., Shepherd, L., Holtom, P., Comparison of anterior and posterior iliac crest bone grafts in terms of harvest-site morbidity and functional outcomes (2002) Journal of Bone and Joint Surgery - Series a, 84 (5), pp. 716-720+Adv46Zipfel, G.J., Guiot, B.H., Fessler, R.G., Bone grafting (2003) Neurosurg Focus, 14, pp. E8Schizas, C., Triantafyllopoulos, D., Kosmopoulos, V., Tzinieris, N., Stafylas, K., Posterolateral lumbar spine fusion using a novel demineralized bone matrix: A controlled case pilot study (2008) Arch Orthop Trauma Surg, 128, pp. 621-625Boden, S.D., Davis, D.O., Dina, T.S., Patronas, N.J., Wiesel, S.W., Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. a prospective investigation (1990) Journal of Bone and Joint Surgery - Series a, 72 (3), pp. 403-408Hsu, W.K., Wang, J.C., The use of bone morphogenetic protein in spine fusion (2008) Spine J, 8, pp. 419-425Shields, L.B., Raque, G.H., Glassman, S.D., Adverse effects associated with high-dose recombinant human bone morphogenetic protein-2 use in anterior cervical spine fusion (2006) Spine, 31, pp. 542-547Glassman, S.D., Carreon, L., Djurasovic, M., Campbell, M.J., Puno, R.M., Johnson, J.R., Dimar, J.R., Posterolateral lumbar spine fusion with INFUSE bone graft (2007) Spine Journal, 7 (1), pp. 44-49. , DOI 10.1016/j.spinee.2006.06.381, PII S1529943006006930Shim, C.S., Lee, S.H., Shin, H.D., Charite versus ProDisc: A comparative study of a minimun 3-year follow-up (2007) Spine, 32, pp. 1012-1018Guyer, R.D., McAfee, P.C., Hochschuler, S.H., Prospective randomized study of the Charite artificial disc: Data from two investigational centers (2004) Spine J, 4, pp. 252-259Andeson, P.A., Tribus, C.B., Kitchel, S.H., Treatment of neurogenic claudication by interspinous decompression: Application of the X STOP device in patients with lumbar degenerative spondylolisthesis (2006) J Neurosurg Spine, 4, pp. 463-471Kondrashov, D.G., Hannibal, M., Hsu, K.Y., Zucherman, J.F., Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: A 4-year follow-up study (2006) Journal of Spinal Disorders and Techniques, 19 (5), pp. 323-327. , DOI 10.1097/01.bsd.0000211294.67508.3b, PII 0002472020060700000004Welch, W.C., Cheng, B.C., Awad, T.E., Clinical outcomes of the Dynesys dynamic neutralization system: 1-year preliminary results (2007) Neurosurg Focus, 22, pp. E8Siepe, C.J., Mayer, H.M., Wiechert, K., Korge, A., Clinical results of total lumbar disc replacement with ProDisc II: Three-year results for different indications (2006) Spine, 31 (17), pp. 1923-1932. , DOI 10.1097/01.brs.0000228780.06569.e8, PII 000076322006080100000

    Comparison of Coulomb Blockade Thermometers with the International Temperature Scale PLTS-2000

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    The operation of the primary Coulomb blockade thermometer (CBT) is based on a measurement of bias voltage dependent conductance of arrays of tunnel junctions between normal metal electrodes. Here we report on a comparison of a CBT with a high accuracy realization of the PLTS-2000 temperature scale in the range from 0.008 K to 0.65 K. An overall agreement of about 1% was found for temperatures above 0.25 K. For lower temperatures increasing differences are caused by thermalization problems which are accounted for by numerical calculations based on electron-phonon decoupling.Comment: 6 pages, 5 figure

    Temperature dependent resistivity of spin-split subbands in GaAs 2D hole system

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    We calculate the temperature dependent resistivity in spin-split subbands induced by the inversion asymmetry of the confining potential in GaAs 2D hole systems. By considering both temperature dependent multisubband screening of impurity disorder and hole-hole scattering we find that the strength of the metallic behavior depends on the symmetry of the confining potential (i.e., spin-splitting) over a large range of hole density. At low density above the metal-insulator transition we find that effective disorder reduces the enhancement of the metallic behavior induced by spin-splitting. Our theory is in good qualitative agreement with existing experiments

    Mild parenchymal lung disease and/or low diffusion capacity impacts survival and treatment response in patients diagnosed with idiopathic pulmonary arterial hypertension

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    There are limited published data defining survival and treatment response in patients with mild lung disease and/or reduced gas transfer who fulfil diagnostic criteria for idiopathic pulmonary arterial hypertension (IPAH). Patients diagnosed with IPAH between 2001–19 were identified in the ASPIRE registry. Using pre-specified criteria based on CT imaging and spirometry, patients with a diagnosis of IPAH and no lung disease were termed IPAHno-LD (n=303), and those with minor-mild emphysema or fibrosis were described as IPAHmild-LD (n=190). Survival was significantly better in IPAHno-LD than in IPAHmild-LD (1 and 5-year survival 95% and 70% versus 78% and 22% respectively, p<0.0001). In the combined group of IPAHno-LD and IPAHmild-LD, independent predictors of higher mortality were increasing age, lower DLCO, lower exercise capacity and a diagnosis of IPAHmild-LD (p all <0.05). Exercise capacity and quality of life improved (p both <0.0001) following treatment in patients with IPAHno-LD but not IPAHmild-LD. A proportion of patients with IPAHno-LD had a DLCO <45%; these patients had poorer survival than patients with DLCO ≥45% although demonstrated improved exercise capacity following treatment. The presence of even mild parenchymal lung disease in patients who would be classified as IPAH according to current recommendations has a significant adverse effect on outcomes. This phenotype can be identified using lung function testing and clinical CT reports. Patients with IPAH, no lung disease and severely reduced DLCO may represent a further distinct phenotype. These data suggest that RCTs of targeted therapies in patients with these phenotypes are required

    Cryogenic Characterization of Commercial SiC Power MOSFETs

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    The cryogenic performance of two commercially available SiC power MOSFETs are presented in this work. The devices are characterised in static and dynamic tests at 10 K intervals from 20-320 K. Static current-voltage characterisation indicates that at low temperatures threshold voltage, turn-on voltage, on-state resistance, transconductance, and the body diode turn-on voltage all increase while saturation current decreases. Dynamic, 60 V, 3A switching tests within the cryogenic chamber are also reported and the trends of switching speed, losses, and total power losses, which rise at low temperature, are presented. Overall, both MOSFETs are fully operable down to 20 K with both positive and negative changes in behaviour.</p

    Octonion Quantum Chromodynamics

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    Starting with the usual definitions of octonions, an attempt has been made to establish the relations between octonion basis elements and Gell-Mann \lambda matrices of SU(3)symmetry on comparing the multiplication tables for Gell-Mann \lambda matrices of SU(3)symmetry and octonion basis elements. Consequently, the quantum chromo dynamics (QCD) has been reformulated and it is shown that the theory of strong interactions could be explained better in terms of non-associative octonion algebra. Further, the octonion automorphism group SU(3) has been suitably handled with split basis of octonion algebra showing that the SU(3)_{C}gauge theory of colored quarks carries two real gauge fields which are responsible for the existence of two gauge potentials respectively associated with electric charge and magnetic monopole and supports well the idea that the colored quarks are dyons

    Optimising approximate entropy for assessing cardiac dyssynchrony with radionuclide ventriculography

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    Left ventricular dyssynchrony can be assessed with phase parameters from radionuclide ventriculography (RNVG), including approximate entropy (ApEn). The input values used to calculate ApEn will affect the results significantly, so it is essential to optimise ApEn for the application. However to date, no optimisation for ApEn applied to images has been published. In this paper, generated data were used to simulate patient phase images, allowing the input parameters for ApEn to be tested and optimised in a controlled environment. Clinical images were then used to confirm that the selected parameters were appropriate. The results demonstrate the effect of input parameters for ApEn and the most appropriate use with RNVG phase images. This work demonstrates the importance of optimisation and standardisation when using ApEn as a measure of dyssynchrony

    Heteroepitaxial Beta-Ga2O3 on 4H-SiC for an FET With Reduced Self Heating

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    A method to improve thermal management of β-Ga 2 O 3 FETs is demonstrated here via simulation of epitaxial growth on a 4H-SiC substrate. Using a recently published device as a model, the reduction achieved in self-heating allows the device to be driven at higher gate voltages and increases the overall performance. For the same operating parameters an 18% increase in peak drain current and 15% reduction in lattice temperature are observed. Device dimensions may be substantially reduced without detriment to performance and normally off operation may be achieved

    Radionuclide ventriculography phase analysis for risk stratification of patients undergoing cardiotoxic cancer therapy

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    Background: Accurate diagnostic tools to identify patients at risk of cancer therapy-related cardiac dysfunction (CTRCD) are critical. For patients undergoing cardiotoxic cancer therapy, ejection fraction assessment using radionuclide ventriculography (RNVG) is commonly used for serial assessment of left ventricular (LV) function. Methods: In this retrospective study, approximate entropy (ApEn), synchrony, entropy, and standard deviation from the phase histogram (phase SD) were investigated as potential early markers of LV dysfunction to predict CTRCD. These phase parameters were calculated from the baseline RNVG phase image for 177 breast cancer patients before commencing cardiotoxic therapy. Results: Of the 177 patients, 11 had a decline in left ventricular ejection fraction (LVEF) of over 10% to an LVEF below 50% after treatment had commenced. This patient group had a significantly higher ApEn at baseline to those who maintained a normal LVEF throughout treatment. Of the parameters investigated, ApEn was superior for predicting the risk of CTRCD. Combining ApEn with the baseline LVEF further improved the discrimination between the groups. Conclusions: The results suggest that RNVG phase analysis using approximate entropy may aid in the detection of sub-clinical LV contraction abnormalities, not detectable by baseline LVEF measurement, predicting a subsequent decline in LVEF
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