1,683 research outputs found

    Generalized Ricci Curvature Bounds for Three Dimensional Contact Subriemannian manifolds

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    Measure contraction property is one of the possible generalizations of Ricci curvature bound to more general metric measure spaces. In this paper, we discover sufficient conditions for a three dimensional contact subriemannian manifold to satisfy this property.Comment: 49 page

    Direct intra-abdominal pressure monitoring via piezoresistive pressure measurement: a technical note

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    <p>Abstract</p> <p>Background</p> <p>Piezoresistive pressure measurement technique (PRM) has previously been applied for direct IAP measurement in a porcine model using two different devices. Aim of this clinical study was to assess both devices regarding complications, reliability and agreement with IVP in patients undergoing elective abdominal surgery.</p> <p>Methods</p> <p>A prospective cohort study was performed in 20 patients randomly scheduled to receive PRM either by a Coach<sup>®</sup>-probe or an Accurate++<sup>®</sup>-probe (both MIPM, Mammendorf, Germany). Probes were placed on the greater omentum and passed through the abdominal wall paralleling routine drainages. PRM was compared with IVP measurement by t-testing and by calculating mean difference as well as limits of agreement (LA).</p> <p>Results</p> <p>There were no probe related complications. Due to technical limitations, data could be collected in 3/10 patients with Coach<sup>® </sup>and in 7/10 patients with Accurate++<sup>®</sup>. Analysis was carried out only for Accurate++<sup>®</sup>. Mean values did not differ to mean IVP values. Mean difference to IVP was 0.1 ± 2.8 mmHg (LA: -5.5 to 5.6 mmHg).</p> <p>Conclusion</p> <p>Direct IAP measurement was clinically uneventful. Although results of Accurate++<sup>® </sup>were comparable to IVP, the device might be too fragile for IAP measurements in the clinical setting. Local ethical committee trial registration: EK2024</p

    Ioffe Times in DIS from a Dipole Model Fit

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    We present a study of Ioffe times in deep inelastic electron-proton scattering. We deduce 'experimental' Ioffe-time distributions from the small-x HERA data as described by a particular colour-dipole-model fit. We show distributions for three representative gamma*-proton c.m. energies W and various values of the photon virtuality Q^2. These distributions are rather broad for transversely and very narrow for longitudinally polarised virtual photons. The Ioffe times for W=150 GeV, for example, range from around 1000 fm for Q^2=1 GeV^2 to around 10 fm for Q^2=100 GeV^2. Based on our results we discuss consequences for the limitations of applicability of the dipole picture.Comment: 20 page

    A comparison of echocardiographic and electron beam computed tomographic assessment of aortic valve area in patients with valvular aortic stenosis

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    The purpose of this study was to compare electron beam computed tomography (EBT) with transthoracic echocardiography (TTE) in determining aortic valve area (AVA). Thirty patients (9 females, 21 males) underwent a contrast-enhanced EBT scan (e-Speed, GE, San Francisco, CA, USA) and TTE within 17 ± 12 days. In end-inspiratory breath hold, a prospectively ecg-triggered scan was acquired with a beam speed of 50–100 ms, a collimation of 2 × 1.5 mm and an increment of 3.0 mm. The AVA was measured with planimetry. A complete TTE study was performed in all patients, and the AVA was computed using the continuity equation. There was close correlation between AVA measured with EBT and AVA assessed with TTE (r = 0.60, P < 0.01). The AVA measured with EBT was 0.51 ± 0.46 cm2 larger than the AVA calculated with TTE measurements. EBT appeared to be a valuable non-invasive method to measure the AVA. EBT measures the anatomical AVA, while with TTE the functional AVA is calculated, which explains the difference in results between the methods

    Cerebral involvement in a patient with Goodpasture's disease due to shortened induction therapy: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Goodpasture's disease is a rare immunological disease with formation of pathognomonic antibodies against renal and pulmonary basement membranes. Cerebral involvement has been reported in several cases in the literature, yet the pathogenetic mechanism is not entirely clear.</p> <p>Case presentation</p> <p>A 21-year-old Caucasian man with Goodpasture's disease and end-stage renal disease presented with two generalized seizures after a period of mild cognitive disturbance. Blood pressure and routine laboratory tests did not exceed the patient's usual values, and examination of cerebrospinal fluid was unremarkable. Cerebral magnetic resonance imaging (MRI) revealed multiple cortical and subcortical lesions on fluid-attenuated inversion recovery sequences. Since antiglomerular basement membrane antibodies were found to be positive with high titers, plasmapheresis was started. In addition, cyclophosphamide pulse therapy was given on day 13. Encephalopathy and MRI lesions disappeared during this therapy, and antiglomerular basement membrane antibodies were significantly reduced. Previous immunosuppressive therapy was performed without corticosteroids and terminated early after 3 months.</p> <p>The differential diagnostic considerations were cerebral vasculitis and posterior reversible encephalopathy syndrome. Vasculitis could be seen as an extrarenal manifestation of the underlying disease. Posterior reversible encephalopathy syndrome, on the other hand, can be triggered by immunosuppressive therapy and may appear without a hypertensive crisis.</p> <p>Conclusion</p> <p>A combination of central nervous system symptoms with a positive antiglomerular basement membrane test in a patient with Goodpasture's disease should immediately be treated as an acute exacerbation of the disease with likely cross-reactivity of antibodies with the choroid plexus. In our patient, a discontinuous strategy of immunosuppressive therapy may have favored recurrence of Goodpasture's disease.</p

    Diagnostic role of new Doppler index in assessment of renal artery stenosis

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    BACKGROUND: Renal artery stenosis (RAS) is one of the main causes of secondary systemic arterial hypertension. Several non-invasive diagnostic methods for RAS have been used in hypertensive patients, such as color Doppler ultrasound (US). The aim of this study was to assess the sensitivity and specificity of a new renal Doppler US direct-method parameter: the renal-renal ratio (RRR), and compare with the sensitivity and specificity of direct-method conventional parameters: renal peak systolic velocity (RPSV) and renal aortic ratio (RAR), for the diagnosis of severe RAS. METHODS: Our study group included 34 patients with severe arterial hypertension (21 males and 13 females), mean age 54 (± 8.92) years old consecutively evaluated by renal color Doppler ultrasound (US) for significant RAS diagnosis. All of them underwent digital subtraction arteriography (DSA). RAS was significant if a diameter reduction > 50% was found. The parameters measured were: RPSV, RAR and RRR. The RRR was defined as the ratio between RPSV at the proximal or mid segment of the renal artery and RPSV measured at the distal segment of the renal artery. The sensitivity and specificity cutoff for the new RRR was calculated and compared with the sensitivity and specificity of RPSV and RAR. RESULTS: The accuracy of the direct method parameters for significant RAS were: RPSV >200 cm/s with 97% sensitivity, 72% specificity, 81% positive predictive value and 95% negative predictive value; RAR >3 with 77% sensitivity, 90% specificity, 90% positive predictive value and 76% negative predictive value. The optimal sensitivity and specificity cutoff for the new RRR was >2.7 with 97% sensitivity (p < 0.004) and 96% specificity (p < 0.02), with 97% positive predictive value and 97% negative predictive value. CONCLUSION: The new RRR has improved specificity compared with the direct method conventional parameters (RPSV >200cm/s and RAR >3). Both RRR and RPSV show better sensitivity than RAR for the RAS diagnosis
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