Background
In staged liver resections, associating liver partition and portal ligation for staged hepatectomy (ALPPS) achieves sufficient hypertrophy of the future liver remnant (FLR) in 7 days. This ...is based on portal vein ligation and transection, and on occlusion of intrahepatic collaterals. This article presents a new surgical technique for achieving rapid hypertrophy of the FLR, which also involves adding intrahepatic collateral occlusion to portal vein transection.
Methods
Patients scheduled for two‐stage liver resection for primary or secondary liver tumours, in whom the FLR was considered too small, were enrolled prospectively. In the first stage, a tourniquet was placed around the parenchymal transection line, and the right portal vein was ligated and cut (associating liver tourniquet and portal ligation for staged hepatectomy, ALTPS). The tourniquet was placed on the umbilical ligament if a staged right trisectionectomy was planned, and on Cantlie's line for staged right hepatectomy.
Results
From September 2011, 22 ALTPS procedures were carried out (right trisectionectomy in 15, right hepatectomy in 7). Median FLR at 7 days increased from 410 to 700 ml (median increase 61 (range 33–189) per cent). The median duration of the first stage was 125 min and no patient received a blood transfusion. The median duration of the second stage was 150 min and five patients required a blood transfusion. Fourteen patients had complications, most frequently infected collections, and five patients developed postoperative liver failure. Two patients died.
Conclusion
The ALTPS technique achieved adequate hypertrophy of the FLR after 7 days. It may provide a less aggressive modification of the ALPPS procedure.
Simplification of the ALPPS procedure
Mechanisms of acute cellular allograft rejection followed liver transplantation employs the activation, proliferation and differentiation of CD4+CD154+ and CD8+CD154+ T cells into effector cells ...triggered by direct allorecognition pathway, which is performed by both but is dominated by CD4+ T cells, and indirect allorecognition pathway virtually restricted to CD8+ T cells·
Summary
Decreasing graft rejection and increasing graft and patient survival are great challenges facing liver transplantation (LT). Different T cell subsets participate in the acute cellular rejection (ACR) of the allograft. Cell‐mediated immunity markers of the recipient could help to understand the mechanisms underlying acute rejection. This study aimed to analyse different surface antigens on T cells in a cohort of adult liver patients undergoing LT to determine the influence on ACR using multi‐parametric flow cytometry functional assay. Thirty patients were monitored at baseline and during 1 year post‐transplant. Two groups were established, with (ACR) and without (NACR) acute cellular rejection. Leukocyte, total lymphocyte, percentages of CD4+CD154+ and CD8+CD154+ T cells, human leukocyte antigen (HLA) mismatch between recipient–donor and their relation with ACR as well as the acute rejection frequencies were analysed. T cells were stimulated with concanavalin A (Con‐A) and surface antigens were analysed by fluorescence activated cell sorter (FACS) analysis. A high percentage of CD4+CD154+ T cells (P = 0·001) and a low percentage of CD8+CD154+ T cells (P = 0·002) at baseline were statistically significant in ACR. A receiver operating characteristic analysis determined the cut‐off values capable to stratify patients at high risk of ACR with high sensitivity and specificity for CD4+CD154+ (P = 0·001) and CD8+CD154+ T cells (P = 0·002). In logistic regression analysis, CD4+CD154+, CD8+CD154+ and HLA mismatch were confirmed as independent risk factors to ACR. Post‐transplant percentages of both T cell subsets were significantly higher in ACR, despite variations compared to pretransplant. These findings support the selection of candidates for LT based on the pretransplant percentages of CD4+CD154+ and CD8+CD154+ T cells in parallel with other transplant factors.
Cesium lead halide nanocrystals, CsPbX3 (X = Cl, Br, I), exhibit photoluminescence quantum efficiencies approaching 100% without the core–shell structures usually used in conventional semiconductor ...nanocrystals. These high photoluminescence efficiencies make these crystals ideal candidates for light-emitting diodes (LEDs). However, because of the large surface area to volume ratio, halogen exchange between perovskite nanocrystals of different compositions occurs rapidly, which is one of the limiting factors for white-light applications requiring a mixture of different crystal compositions to achieve a broad emission spectrum. Here, we use mixtures of chloride and iodide CsPbX3 (X = Cl, I) perovskite nanocrystals where anion exchange is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl3 to CsPbI3 in solution and within a poly(methyl methacrylate) matrix via photon reabsorption, which also occurs in electrically excited crystals in bulk heterojunction LEDs.
Long-term care coverage is not integrated into an individual's retirement strategy. It is an additional public health service that is not considered into private pension funds. Nevertheless, this ...coverage is not sufficient due to the problems of financial sustainability of the public pension systems. However, there are large sums in pension plans dedicated to paying retirement pensions that can be transformed into support for long-term care coverage. This paper develops a mechanism of pension transformation through the different mortality of the beneficiary when becoming a dependent beneficiary. This mechanism allows the beneficiary to convert their pension to LTC support at their own choice, without increasing the cost of the private pension scheme. The proposed model provides consistency in the pension that a retiree receives and adapts it to a retiree's life expectancy: the retiree receives a higher pension when he/she needs it most.
In recent years, there has been a change in the main regulations governing the solvency of the world’s main insurance markets. Sustainability is an issue that is becoming increasingly important among ...to the various stakeholders in the insurance industry. It is a complex concept that has many different dimensions that can be included in these regulations, allowing for a more sustainable solvency. The paper uses a qualitative model previously designed and tested in the literature to analyse the solvency regulations of the European Union, United States of America, China, Australia, Brazil and South Africa and determine their level of convergence. It also links the criteria set out in these models to the dimensions of sustainability in order to determine the degree of sustainability of solvency systems and the questions that regulators will need to consider in the near future in order to achieve more sustainable solvency.
A diffractive optical element was fabricated by monolithically integrating two volume phase-gratings (VPGs) in the bulk of a single-piece transparent material. A computer model of the diffraction ...generated by the double volume phase-grating (DVPG) was made with a rigorous coupled wave analysis simulator. Simulations and experiments show that the diffractive behavior of a DVPG can be controlled by arranging the relative displacement and the distance between the VPGs according to Talbot self-imaging planes. In order to diffract the total incident light, the phase accumulation in the VPGs has to be π/2, which was achieved by single-scan femtosecond laser processing of a nanocrystal doped glass as the substrate material. Ex situ microscope images of the cross-sections are presented for laser processed lines in the form of VPGs and DVPGs. The far-field diffraction of DVPGs formed by selectively located VPGs was characterized with a monochromatic 633 nm and a supercontinuum white light. Functional designs of high diffraction efficiency with potential applications in photonics were successfully fabricated in a one-step and free of chemicals process.
An agricultural backhoe is an important machine designed for multiple assignments in agriculture and livestock. Due to severe working conditions, agricultural backhoe elements are subjected to high ...loads. Therefore, a structural design must provide a safe machine under all loading conditions at minimum weight and cost. In this work, a 3D model of an agricultural backhoe was proposed, to be used in tractors category II according to the classification of the ASABE S217 standard. In the structural design of the agricultural backhoe Theoretical Analysis (TA), Finite Element Analysis (FEA), Response Surface Methodology (RSM) and Artificial Neural Network (ANN) were used. A finite element model of the agricultural backhoe in the critical position was developed, considering a maximum breakout force according to SAE J1179 standard. The finite element model was theoretically validated through a comparison between numerical and theoretical normal stresses at twelve strategic points of the agricultural backhoe components, finding a maximum absolute difference of 7.0 %. Also, a mass reduction of the principal backhoe components (bucket, arm, boom and links) was done, using Central Composite Design (CCD) under RSM in a commercial FE software and ANN technique with Neural Lab software. A mass reduction of the initial agricultural backhoe model of 24.8% (from 446.3 kg to 335.4 kg) was achieved using the RSM technique, with an increment on the maximum von Mises stress of 6.8% (from 117.4 MPa to 125.4 MPa), as well as a reduction of the minimum safety factor of 4.8% (from 2.94 to 2.80). ANN allowed predicting the results obtained by RSM to reduce the boom mass with a correlation coefficient of 0.96, using 80.0% of data and around 13.0% less time. This study showed that a combination of RSM and ANN techniques with TA and FEA provides useful results to reduce the structural mass of agricultural equipments, thus it is recommended to decrease the number of numerical case studies and the solution time with satisfactory results.
Purpose - This paper analyses the suitability of different regulatory systems for the solvency of insurance companies. Teoretical framework - The insurance sector is in the midst of a global process ...of change. There are different systems and each of them faces insolvency in a different way, although they all provide optimal capital with which to deal with undesirable situations. This study focuses on Latin America, where the sector is becoming increasingly important. Brazil, Mexico and Argentina are the most relevant countries in terms of annual premium volume. Design/methodology/approach - This paper uses the structure designed by Cummins et al. (1994) to check whether the regulations are suitable for reducing the number of insolvencies. Findings - The review of the regulations in these countries shows that they have all been reformed, following the trend in the insurance sector over the last decade, although the degree of legislative development is greater in some than in others. The involvement of the system must take place at two levels: on the part of the insurer, with the periodic self-assessment of risks; and on the part of the regulator, with the periodic review of the system as a whole. Practical & social implications of research - This paper contributes to the literature by proposing the lines of work necessary for the globalisation of insurance sector regulation in Latin America. Originality/value - The main conclusion is that regulatory systems must increase their qualitative approach to risk management, not only in the number of calculations but also by increasing governance, transparency and risk control.
•Mechanical contact can be used for health monitoring of engineering structures.•Lamb wave characteristics can be used as reference for structural health monitoring.•Variation of S0 mode is ...characterized as function of imperfect contact conditions.•Numerical results of Lamb wave propagation were experimentally corroborated.
In this work, fundamental symmetric Lamb wave S0 mode is characterized in terms of its velocity variation as function of the interfacial conditions between solid bodies in contact. Imperfect contact conditions are numerically and experimentally determined by using ultrasonic Lamb wave propagation parameters. For the study, an experimental system was used, formed by two solid aluminum rods (25.4mm in diameter) axially loading a thin aluminum plate to control contact interfacial stiffness. The axially applied load on the aluminum plate was varied from 0MPa to 10MPa. Experimental Lamb wave signals were excited on the plate through two longitudinal contact transducers (1MHz of central frequency) using a pitch-catch configuration. Numerical simulations of contact conditions and Lamb wave propagation were performed through Finite Element Analysis (FEA) in commercial software, ANSYS 15®. Simulated Lamb wave signals were generated by means of a 5 cycles tone burst signals with different frequency values. Results indicate a velocity change in both, experimental and simulated Lamb wave signals as function of the applied load. Finally, a comparison between numerical results and experimental measurements was performed obtaining a good agreement.
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