894 research outputs found

    Shortening of the Short Refractory Periods in Short QT Syndrome.

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    BACKGROUND: Diagnosis of short QT syndrome (SQTS) remains difficult in case of borderline QT values as often found in normal populations. Whether some shortening of refractory periods (RP) may help in differentiating SQTS from normal subjects is unknown. METHODS AND RESULTS: Atrial and right ventricular RP at the apex and right ventricular outflow tract as determined during standard electrophysiological study were compared between 16 SQTS patients (QTc 324±24 ms) and 15 controls with similar clinical characteristics (QTc 417±32 ms). Atrial RP were significantly shorter in SQTS compared with controls at 600- and 500-ms basic cycle lengths. Baseline ventricular RP were significantly shorter in SQTS patients than in controls, both at the apex and right ventricular outflow tract and for any cycle length. Differences remained significant for RP of any subsequent extrastimulus at any cycle length and any pacing site. A cut-off value of baseline RP <200 ms at the right ventricular outflow tract either at 600- or 500-ms cycle length had a sensitivity of 86% and a specificity of 100% for the diagnosis of SQTS. CONCLUSIONS: Patients with SQTS have shorter ventricular RP than controls, both at baseline during various cycle lengths and after premature extrastimuli. A cut-off value of 200 ms at the right ventricular outflow tract during 600- and 500-ms basic cycle length may help in detecting true SQTS from normal subjects with borderline QT values

    Field Theory And Second Renormalization Group For Multifractals In Percolation

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    The field-theory for multifractals in percolation is reformulated in such a way that multifractal exponents clearly appear as eigenvalues of a second renormalization group. The first renormalization group describes geometrical properties of percolation clusters, while the second-one describes electrical properties, including noise cumulants. In this context, multifractal exponents are associated with symmetry-breaking fields in replica space. This provides an explanation for their observability. It is suggested that multifractal exponents are ''dominant'' instead of ''relevant'' since there exists an arbitrary scale factor which can change their sign from positive to negative without changing the Physics of the problem.Comment: RevTex, 10 page

    The impact of ICT capital accumulation - A complete macroeconomic framework

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    The paper aims at assessing the net impact of the accumulation of Information and Communication Technologies (ICT) capital on the economy. In a first part, focusing on the supply-side of the economy, we show that the growth accounting methodology cannot provide us with a measure of the net economic impact of ICT capital accumulation, since it does not take into account substitution between production factors. We develop a theoretical framework relying on the profit optimizing behaviour of firms that enables us to quantify the missing terms. Applying to French data over the period 1995-2000, with reasonable assumptions on elasticities of substitution, we find that the net impact of ICT capital accumulation on labour productivity growth is half the one computed by growth accounting studies. In a second part, we use this long-term framework in a macroeconometric model. We find that long-term effects have a small magnitude, and the demand effects are the larger ones over the period 1995-2000. However, total impact is rather weak, less than 0.1 percentage of PIB per year.growth accounting, aggregate productivity, elasticity of substitution, information and communication technologies, macroeconometric models

    Romeo Pepoli. Patrimonio e potere a Bologna fra Comune e Signoria

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    Karl Marx observed long ago that all economic struggles invite moral struggles, or masquerade as such. The reverse may be true as well: deep moral-political conflicts may be waged through the manipulation of economic resources. Using the recent financial and Eurozone crises as empirical backgrounds, the four papers gathered here propose four different perspectives on the play of moral judgments in the economy, and call for broader and more systematic scholarly engagement with this issue. Focusing on executive compensation, bank bailouts, and the sovereign debt crisis, the symposium builds on a roundtable discussion held at the opening of the Max Planck Sciences Po Center on Coping with Instability in Market Societies (MaxPo) in Paris on November 29, 2012.Introduction Marion Fourcade and Cornelia Woll High wages in the financial crisis Philippe Steiner The morality of rescuing banks Cornelia Woll The construction of a moral duty for the Greek people to repay their national debt Wolfgang Streeck The economy as morality play, and implications for the Eurozone crisis Marion Fourcad

    Design of micromixers using CFD modelling

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    The effect of various geometrical parameters of a grooved staggered herringbone micromixer on the mixing performance has been investigated using Computational Fluid Dynamics. Mixing quality has been quantified with spatial data statistics, maximum striation thickness and residence time analyses. The results show that the number of grooves per mixing cycle does not affect the mixing quality in an important way. On the other hand, a larger groove depth and width allow the maximum striation thickness to be rapidly reduced, without increasing the pressure drop across the mixer. Wide grooves, however, create significant dead zones in the microchannel, whereas deep grooves improve the spatial mixing quality

    Hypocycloid-shaped hollow-core photonic crystal fiber Part II: Cladding effect on confinement and bend loss

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    We report on numerical and experimental studies on the influence of cladding ring-number on the confinement and bend loss in hypocycloid-shaped Kagome hollow core photonic crystal fiber. The results show that beyond the second ring, the ring number has a minor effect on confinement loss whereas the bend loss is strongly reduced with the ringnumber increase. Finally, the results show that the increase in the cladding ring-number improves the modal content of the fiber

    Postoperative bladder dysfunction and outcomes after minimally invasive extravesical ureteric reimplantation in children using a laparoscopic and a robot-assisted approach: results of a multicentre international survey

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    OBJECTIVES: To assess and compare postoperative bladder dysfunction rates and outcomes after laparoscopic and robot-assisted extravesical ureteric reimplantation in children and to identify risk factors associated with bladder dysfunction. PATIENTS AND METHODS: A total of 151 children underwent minimally invasive extravesical ureteric reimplantation in five international centres of paediatric urology over a 5-year period (January 2013-January 2018). The children were divided in two groups according to surgical approach: group 1 underwent laporoscopic reimplantation and included 116 children (92 girls and 24 boys with a median age of 4.5 years), while group 2 underwent robot-assisted reimplantation and included 35 children (29 girls and six boys with a median age of 7.5 years). The two groups were compared with regard to: procedure length; success rate; postoperative complication rate; and postoperative bladder dysfunction rate (acute urinary retention [AUR] and voiding dysfunction). Univariate and multivariate logistic regression analyses were performed to assess predictors of postoperative bladder dysfunction. Factors assessed included age, gender, laterality, duration of procedure, pre-existing bladder and bowel dysfunction (BBD) and pain control. RESULTS: The mean operating time was significantly longer in group 2 compared with group 1, for both unilateral (159.5 vs 109.5 min) and bilateral procedures (202 vs 132 min; P = 0.001). The success rate was significantly higher in group 2 than in group 1 (100% vs 95.6%; P = 0.001). The overall postoperative bladder dysfunction rate was 8.6% and no significant difference was found between group 1 (6.9%) and group 2 (14.3%; P = 0.17). All AUR cases were managed with short-term bladder catheterization except for two cases (1.3%) in group 1 that required short-term suprapubic catheterization. Univariate and multivariate analyses showed that bilateral pathology, pre-existing BBD and duration of procedure were predictors of postoperative bladder dysfunction (P = 0.001). CONCLUSION: Our results confirmed that short-term bladder dysfunction is a possible complication of extravesical ureteric reimplantation, with no significant difference between the laparoscopic and robot-assisted approaches. Bladder dysfunction occurred more often after bilateral repairs, but required suprapubic catheterization in only 1.3% of cases. Bilaterality, pre-existing BBD and duration of surgery were confirmed on univariate and multivariate analyses as predictors of postoperative bladder dysfunction in this series

    Bond-charge Interaction in the extended Hubbard chain

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    We study the effects of bond-charge interaction (or correlated hopping) on the properties of the extended ({\it i.e.,} with both on-site (UU) and nearest-neighbor (VV) repulsions) Hubbard model in one dimension at half-filling. Energy gaps and correlation functions are calculated by Lanczos diagonalization on finite systems. We find that, irrespective of the sign of the bond-charge interaction, XX, the charge--density-wave (CDW) state is more robust than the spin--density-wave (SDW) state. A small bond-charge interaction term is enough to make the differences between the CDW and SDW correlation functions much less dramatic than when X=0X=0. For X=tX=t and fixed V<2tV<2t (tt is the uncorrelated hopping integral), there is an intermediate phase between a charge ordered phase and a phase corresponding to singly-occupied sites, the nature of which we clarify: it is characterized by a succession of critical points, each of which corresponding to a different density of doubly-occupied sites. We also find an unusual slowly decaying staggered spin-density correlation function, which is suggestive of some degree of ordering. No enhancement of pairing correlations was found for any XX in the range examined.Comment: 10 pages, 7 PostScript figures, RevTeX 3; to appear in Phys Rev
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