Search results for "dilations"
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Hilbert space operators with two-isometric dilations
2021
A bounded linear Hilbert space operator $S$ is said to be a $2$-isometry if the operator $S$ and its adjoint $S^*$ satisfy the relation $S^{*2}S^{2} - 2 S^{*}S + I = 0$. In this paper, we study Hilbert space operators having liftings or dilations to $2$-isometries. The adjoint of an operator which admits such liftings is characterized as the restriction of a backward shift on a Hilbert space of vector-valued analytic functions. These results are applied to concave operators (i.e., operators $S$ such that $S^{*2}S^{2} - 2 S^{*}S + I \le 0$) and to operators similar to contractions or isometries. Two types of liftings to $2$-isometries, as well as the extensions induced by them, are construct…
W1113 Efficacy and Safety of Endoscopic Balloon Dilation of Symptomatic Intestinal Crohn's Disease Strictures
2009
Aim: To evaluate prospectively the clinical efficacy and safety of endoscopic hydrostatic balloon dilation in a consecutive cohort of symptomatic intestinal Crohn’s disease strictures. Methods: Between September 2003 and December 2008 we performed endoscopic balloon dilations in 37 Crohn’s disease patients with 39 intestinal symptomatic strictures (4 naive and 35 postoperative). Dilations were performed using a Rigiflex through-the-scope balloon. Clinical success rate was claimed if a patient remained asymptomatic and did not require surgery or further endoscopic dilation, following technical success. Actuarial curves of clinical, endoscopic (redilation) and surgical recurrence were obtaine…
Efficacy and safety of endoscopic balloon dilation of symptomatic intestinal Crohn's disease strictures
2011
Abstract Aim To evaluate prospectively the clinical efficacy and safety of endoscopic hydrostatic balloon dilation in a consecutive cohort of symptomatic intestinal Crohn's disease strictures. Methods Between September 2003 and December 2008 we performed endoscopic balloon dilations in 37 Crohn's disease patients with 39 intestinal symptomatic strictures (4 naive and 35 postoperative). Dilations were performed using a Rigiflex through-the-scope balloon. Clinical success rate was claimed if a patient remained asymptomatic and did not require surgery or further endoscopic dilation, following technical success. Actuarial curves of clinical, endoscopic (redilation) and surgical recurrence were …