969 research outputs found
National variations in perioperative assessment and surgical management of Crohn's disease: a multicentre study
Aim: Crohn's disease (CD) requires a multidisciplinary approach and surgery should be undertaken by dedicated colorectal surgeons with audited outcomes. We present a national, multicentre study, with the aim to collect benchmark data on key performance indicators in CD surgery, to highlight areas where standards of CD surgery excel and to facilitate targeted quality improvement where indicated.
Methods: All patients undergoing ileocaecal or redo ileocolic resection in the participating centres for primary and recurrent CD from June 2018 to May 2019 were included. The main objective was to collect national data on hospital volume and practice variations. Postoperative morbidity was the primary outcome. Laparoscopic surgery and stoma rate were the secondary outcomes.
Results: In all, 715 patients were included: 457 primary CD and 258 recurrent CD with a postoperative morbidity of 21.6% and 34.7%, respectively. Laparoscopy was used in 83.8% of primary CD compared to 31% of recurrent CD. Twenty-five hospitals participated and the total number of patients per hospital ranged from 2 to 169. Hospitals performing more than 10 primary CD procedures per year showed a higher adoption of laparoscopy and bowel sparing surgery.
Conclusions: There is significant heterogeneity in the number of CD surgeries performed per year nationally in Italy. Our data suggest that high-volume hospitals perform more complex procedures, with a higher adoption of bowel sparing surgery. The rate of laparoscopy in high-volume hospitals is higher for primary CD but not for recurrent CD compared with low-volume hospitals
National variations in perioperative assessment and surgical management of Crohn's disease: a multicentre study
Aim Crohn's disease (CD) requires a multidisciplinary approach and surgery should be undertaken by dedicated colorectal surgeons with audited outcomes. We present a national, multicentre study, with the aim to collect benchmark data on key performance indicators in CD surgery, to highlight areas where standards of CD surgery excel and to facilitate targeted quality improvement where indicated. Methods All patients undergoing ileocaecal or redo ileocolic resection in the participating centres for primary and recurrent CD from June 2018 to May 2019 were included. The main objective was to collect national data on hospital volume and practice variations. Postoperative morbidity was the primary outcome. Laparoscopic surgery and stoma rate were the secondary outcomes. Results In all, 715 patients were included: 457 primary CD and 258 recurrent CD with a postoperative morbidity of 21.6% and 34.7%, respectively. Laparoscopy was used in 83.8% of primary CD compared to 31% of recurrent CD. Twenty-five hospitals participated and the total number of patients per hospital ranged from 2 to 169. Hospitals performing more than 10 primary CD procedures per year showed a higher adoption of laparoscopy and bowel sparing surgery. Conclusions There is significant heterogeneity in the number of CD surgeries performed per year nationally in Italy. Our data suggest that high-volume hospitals perform more complex procedures, with a higher adoption of bowel sparing surgery. The rate of laparoscopy in high-volume hospitals is higher for primary CD but not for recurrent CD compared with low-volume hospitals
Directional pinning and anisotropy in YBa2Cu3O7-x with BaZrO3 nanorods: intrinsic and nanorods-induced anisotropy
We present a study of the anisotropic vortex parameters as obtained from
measurements of the microwave complex resistivity in the vortex state with a
tilted applied magnetic field in YBa2Cu3O7-x thin films with BaZrO3 nanorods.
We present the angular dependence of the vortex viscosity , the pinning
constant k_p and the upper limit for the creep factor \chi_M. We show that the
directional effect of the nanorods is absent in \eta, which is dictated by the
mass anisotropy \gamma. By contrast, pinning-mediated properties are strongly
affected by the nanorods. It is significant that the pinning and creep affected
by the nanorods is detectable also at our very high operating frequency, which
implies very short-range displacements of the vortices from their equilibrium
position.Comment: Proceedings of VORTEX VIII Conference, to be published in Physica
Strong reduction of field-dependent microwave surface resistance in YBaCuO with sub-micrometric BaZrO inclusions
We observe a strong reduction of the field induced thin film surface
resistance measured at high microwave frequency (47.7 GHz) in
YBaCuO thin films grown on SrTiO substrates, as a
consequence of the introduction of sub-micrometric BaZrO particles. The
field increase of the surface resistance is smaller by a factor of 3 in
the film with BaZrO inclusions, while the zero-field properties are not
much affected. Combining surface resistance and surface reactance data we
conclude (a) that BaZrO inclusions determine very deep and steep pinning
wells and (b) that the pinning changes nature with respect to the pure film.Comment: RevTeX; 4 pages, 3 figures; submitted to Applied Physics Letter
Reduction of the field-dependent microwave surface resistance in YBa_2Cu_3O_7 with sub-micrometric BaZrO_3 inclusions as a function of BaZrO_3 concentration
In order to study the vortex pinning determined by artificially introduced
pinning centers in the small-vortex displacement regime, we measured the
microwave surface impedance at 47.7 GHz in the mixed state of
YBaCuO thin films, where sub-micrometric BaZrO
particles have been incorporated. As a function of the BaZrO content, we
observe that the absolute losses slightly decrease up to a BaZrO content of
5%, and then increase. We found that the magnetic-field-induced losses behave
differently, in that they are not monotonic with increasing BaZrO
concentration: at small concentration (2.5%) the field-induced losses increase,
but large reduction of the losses themselves, by factors up to 3, is observed
upon further increasing the BaZrO concentration in the target up to 7%.
Using measurements of both surface resistance and surface reactance we estimate
vortex pinning-related parameters. We find that BaZrO inclusions introduce
deep and steep pinning wells. In particular, the minimum height of the energy
barrier for single vortices is raised. At larger BaZrO content (5% and 7%)
the phenomenon is at its maximum, but it is unclear whether it shows a
saturation or not, thus leaving room for further improvements.Comment: 7 pages, 7 figure
A Robust Tracking Method for MIMO Uncertain Discrete-Time Systems: Mechatronic Applications
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Anisotropy and directional pinning in YBaCuO with BaZrO3 nanorods
Measurements of anisotropic transport properties (dc and high-frequency
regime) of driven vortex matter in YBaCuO with elongated
strong-pinning sites (c-axis aligned, self-assembled BaZrO nanorods) are
used to demonstrate that the effective-mass angular scaling takes place only in
intrinsic physical quantities (flux-flow resistivity), and not in
pinning-related Labusch parameter and critical currents. Comparison of the
dynamics at different time scales shows evidence for a transition of the vortex
matter toward a Mott phase, driven by the presence of nanorods. The strong
pinning in dc arises partially from a dynamic effect.Comment: 4 pages, 4 figures. Accepted for publication on Applied Physics
Letters. With respect to v1: changed title, slightly shortene
Majorant-Based Control Methodology for Mechatronic and Transportation Processes
This paper provides a unified approach via majorant systems, which allows one to easily design a family of robust, smooth and effective control laws of proportional - h order integral - k order derivative (PIhDk) -type for broad classes of uncertain nonlinear multi-input multi-output (MIMO) systems, including mechatronic and transportation processes with ideal or real actuators, subject to bounded disturbances and measurement errors. The proposed control laws are simple to design and implement and are used, acting on a single design parameter, to track a sufficiently smooth but generic reference signal, yielding a tracking error norm less than a prescribed value, with a good transient phase and feasible control signals, despite the presence of disturbances, parametric and structural uncertainties, measurement errors, and in case of real actuators and amplifiers. Moreover, some guidelines to easily design the proposed controllers are given. Finally, the stated unified methodology and various performance comparisons are illustrated and validated in two case studies
Exclusive tensor meson photoproduction
We study tensor meson photoproduction outside of the resonance region, at
beam energies of few GeVs. We build a model based on Regge theory that includes
the leading vector and axial exchanges. We consider two determinations of the
unknown helicity couplings, and fit to the recent a2 photoproduction data from
CLAS. Both choices give a similar description of the a2 cross section, but
result in different predictions for the parity asymmetries and the f2
photoproduction cross section. We conclude that new measurements of f2
photoproduction in the forward region are needed to pin down the correct
production mechanism. We also extend our predictions to the 8.5 GeV beam
energy, where current experiments are running.Comment: 13 pages, 7 figures, 3 tables. Version accepted for publication on
Phys.Rev.
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