Our experience with the treatment of large incisional hernias (IH) was reviewed comparing mesh repair alone vs. mesh repair plus pedicle flaps.
A retrospective study was performed on patients treated ...between 2001 and 2005 that underwent component separation technique (CST) repair with polypropylene mesh alone or with polypropylene mesh and local "pedicle" dermal flaps. The primary outcome evaluated was the recurrence rate, secondary outcomes the complication rate, hospital stay and reoperation rate.
Forty-eight patients were reviewed. Six patients (13%) developed an IH recurrence, two of them (4%) required secondary repair. CST combined with prosthetic mesh repair and pedicle flap was performed in 19 patients (39.6%) while CST combined with mesh repair alone in 29 patients (60.4%). The duration of surgery, hospitalization, postoperative complications as well as long-term results were similar.
Dermal pedicled flaps obtained through deepithelization of redundant skin following corrections of large incisional hernias are a safe, relatively easy and effective technique that allows reliable soft tissue coverage of the abdominal submuscular mesh.
In the current work, the study of the aeroelastic behaviour of a wing with external store(s), such as a missile or drop fuel tank, is presented. The aeroelastic governing equations derived for a ...cantilever wing with coupled bending and torsion modes account for structural and aerodynamic non-linearities. Coupling terms retained in the aeroelastic governing equations are due to: (a) the non-linear beam theory, (b) the aerodynamic non-linearities of a quasi-steady model with stall, and (c) the non-linear kinematics terms of the store(s). As presented in the paper, this aircraft configuration can induce pathologies, such as store(s)-induced limit cycle oscillations (or si-LCOs), very different from the one of a clean wing configuration, and from the one obtained from the linearized form of the aeroelastic governing equations. Time domain simulation, phase portrait, and bifurcation analyses are performed for various velocities, initial conditions, and store(s)-sensitive parameters — such as store mass, number, location along the wing — to examine the dynamic aeroelastic instabilities of the system (e.g. the onset of flutter and LCO). Numerical studies indicate the presence of regions of subcritical Hopf-bifurcation, corresponding to an unstable LCO, for velocities below the linear flutter velocity.
Expressions for the bispectral density functions for multi-degree-of-freedom spring–mass–damper systems possessing quadratic nonlinearities and subject to Gaussian excitation are derived. The ...derivation uses a Volterra-series model for the system response and yields expressions for both auto-spectra, where the output of only one degree-of-freedom is used, and cross-spectra, where the bispectral density contains multiple output-response time series. The proposed formulation is used to identify the presence and location of quadratic nonlinearities in multiple degree-of-freedom systems. Results show that the ability to detect and localize nonlinearity is heavily dependent on which particular bispectral density is utilized.
The Short Model Coil (SMC) assembly has been designed, as test bench for short racetrack coils wound with cable. The mechanical structure comprises an iron yoke surrounded by a 20 mm thick aluminum ...alloy shell, and includes four loading pads that transmit the required pre-compression from the outer shell into the two coils. The outer shell is pre-tensioned with mechanical keys that are inserted with the help of pressurized bladders and two 30 mm diameter aluminum alloy rods provide the axial loading to the coil ends. The outer shell, the axial rods, and the coils are instrumented with strain gauges, which allow precise monitoring of the loading conditions during the assembly and at cryogenic temperature during the magnet test. Two SMC assemblies have been completed and cold tested in the frame of a European collaboration between CEA (FR), CERN and STFC (UK) and with the technical support from LBNL (US). This paper describes the main features of the SMC assembly, the experience from the dummy assemblies, the fabrication of the coils, and discusses the test results of the cold tests showing a peak field of 12.5 T at 1.9 K after training.
In this paper, I introduce a comprehensive workflow aimed at optimizing oil production and CO2 geological storage. I show that the same methodology can be applied to different categories of problems: ...a) real-time reservoir fluid mapping for predicting and delaying water breakthrough time as far as possible in oil production; b) real-time CO2 mapping for maximizing the sweep efficiency and storage capacity of CO2 in geological formations. Despite their intrinsic differences, these types of problems share common aspects, issues and possible solutions. In both cases, various geophysical techniques can be applied, including Electric Resistivity Tomography (briefly ERT) for accurate fluid mapping and monitoring. This method is highly effective and sensitive for detecting the type of fluid and for estimating saturation in the geological formations. The robustness and the accuracy of the ERT models increase if densely spaced electrodes layouts are permanently deployed into the production and injection wells. In the first part of the paper, I discuss how in both scenarios of oil production and CO2 storage, we can apply time-lapse borehole ERT method for mapping fluids in the reservoir. Next, I discuss how to apply various techniques of time-series analysis for predicting the evolution of the fluids distribution over time. Finally, using Q-Learning, that is a specific Reinforcement Learning method, I discuss how we can optimize the decisional workflow using our models about past, real-time and predicted fluids displacement. The result is the definition of a "best policy" addressed to both problems of optimized oil production and safe CO2 geological storage. In the second part of the paper, I show benefits and limitations of my approach with the support of synthetic tests.
Abstract
Background
Patients with atrial fibrillation (AF) experience a high mortality rate despite optimal antithrombotic treatment. Characteristics of AF patients at higher mortality risk have been ...barely described so far and no risk score has been specifically developed at this aim. Furthermore, a clinical approach based on risk scores present some limits such as to not consider some important risk factors for mortality, and many available scores have poor predictive value. Cluster analysis may play a role in overcoming limitations of risk scores, especially in the case of overlapping risk factors.
Purpose
To identify of clinical phenotypes by using an unbiased statistical approach, such as the cluster analysis.
Methods
Cluster analysis was used to identify clinical phenotypes of AF patients associated with all-cause mortality in 5,171 AF patients from the START registry. Clinical variables used for the analysis were age, sex, diabetes, previous cerebrovascular events, previous cardiovascular events, heart failure, peripheral artery disease, use of non-vitamin K oral anticoagulants, cancer, pulmonary disease, smoking habit, previous major bleeding. The risk of all-cause mortality in each cluster was analyzed.
Results
We identified 4 clusters (Figure 1). Cluster 1 was composed by youngest patients, with obesity and paroxysmal AF; Cluster 2 by patients with low cardiovascular risk factors and high proportion of cancer; Cluster 3 by men with diabetes and coronary and peripheral artery disease, a high proportion of thrombocytopenia, and a high use of aspirin, proton pump inhibitors, and statins; Cluster 4 included the oldest patients, mainly women, with previous cerebrovascular disease, persistent/ permanent AF, heart failure, kidney disease and anemia. In this cluster there was the highest use of digoxin and NOACs.
During 9856,84 patient/years of observation, 386 deaths (3.92%/year) occurred. Mortality rates significantly increased across clusters: 0.42%/year (cluster 1, reference group), 2.12%/year (cluster 2, adjusted hazard ratio aHR 3.306, 95% confidence interval CI 1.204–9.077, p=0.020), 4.41%/year (cluster 3, aHR 6.702, 95% CI 2.433–18.461, p<0.001) and 8.71%/year (cluster 4, aHR 8.927, 95% CI 3.238–24.605, p<0.001).
Conclusions
We identified different clinical phenotypes of AF patients by cluster analysis which were specifically associated with mortality. This approach may help identify patients at higher risk of mortality.
Figure 1
Funding Acknowledgement
Type of funding source: None
Abstract The future of particle accelerators is strongly linked to the development of high—field magnets. The European Organization for Nuclear Research (CERN) is currently developing Nb 3 Sn-based ...magnets for the high-luminosity upgrade of the large hadron collider (HL-LHC), to fully exploit its potential and surpass the intrinsic performance limitations of Nb–Ti-based magnets. The fabrication of Nb 3 Sn magnets is a challenging process as it requires managing the brittle and strain sensitive conductor after the reaction heat treatment to generate the superconducting phase. Accelerator magnet coils are usually manufactured following the wind-react-and-impregnate fabrication process. This reduces the difficulty of working with brittle compounds but adds uncertainties associated with volume change during phase transition and thermal expansion/contraction differentials during the temperature ramps of the heat treatment and cooldown to cryogenic temperatures. To investigate the root causes of performance limitation or degradation observed on HL-LHC magnet prototypes, several Nb 3 Sn-based coils have been examined. The present paper illustrates an innovative methodology of investigations of the root causes at several fabrication stages and after cooldown and powering. The approach is based on a sequence of mesoscale observations of whole coil sections by an innovative high—energy linac x-ray computed tomography, followed by materialographic assessment of internal events, geometrical distortions and potential flaws using light microscopy. Additionally, scanning electron microscopy and focused ion beam were used to analyze damage at localized positions. This comprehensive approach provides an in-depth view of the examined coils by characterizing atypical features and imperfections in both the strands and the glass fiber/resin of the insulation system, univocally associating the limiting quenches experienced by the coils to identified physical events.
Tests with a prescribed deceleration pulse are fundamental to the development and certification of crashworthy structures. At the Politecnico di Milano Laboratory for the Safety of Transports these ...tests are carried out using a horizontal impact-sled facility. Test articles are mounted on a trolley which is launched down a rail and then arrested by means of a braking system that allows prescribed deceleration pulses to be obtained. The oleo-pneumatic braking system customarily used in these tests is difficult to use and user-defined time-histories of the deceleration pulse cannot be obtained. In an effort to overcome these limits, a new braking system was developed. The idea was to arrest the trolley by means of a number of beams that varied in length and that were positioned at variable distances from each other. Experimental tests and numerical simulations were carried out in parallel to verify the feasibility of the new system and improve on the initial design. A mathematical model and genetic algorithm were also developed and used as part of a method to find the test set-up that allowed user-defined deceleration pulses to be obtained. A full-scale test with the deceleration pulse prescribed for small airplane seat certification was carried out to assess the performance of the braking system. The test revealed a weakness of the braking system that was then further developed before being put into full operational service.
Performance of a Quadrupole Under High Stress Felice, H; Bajko, M; Bingham, B ...
IEEE transactions on applied superconductivity,
2011-June, 2011-06-00, 20110601, Letnik:
21, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Future upgrades of the Large Hadron Collider (LHC) will require large aperture and high gradient quadrupoles. Nb 3 Sn is the most viable option for this application but is also known for its strain ...sensitivity. In high field magnets, with magnetic fields above 12 T, the Lorentz forces will generate mechanical stresses that may exceed 200 MPa in the windings. The existing measurements of critical current versus strain of Nb 3 Sn strands or cables are not easily applicable to magnets. In order to investigate the impact of high mechanical stress on the quench performance, a series of tests was carried out within a LBNL/CERN collaboration using the magnet TQS03 (a LHC Accelerator Research Program (LARP) 1-meter long, 90-mm aperture Nb 3 Sn quadrupole). The magnet was tested four times at CERN under various pre-stress conditions. The average mechanical compressive azimuthal pre-stress on the coil at 4.2 K ranged from 120 MPa to 200 MPa. This paper reports on the magnet performance during the four tests focusing on the relation between pre-stress conditions and the training plateau.
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