The exact theory for scattering of waves by thick holes in a slab and other objects with non-separable geometries

The theory for scattering of electromagnetic waves is developed for scattering objects for which the natural modes of the field inside the object do not couple one-to-one with those outside the scatterer. Key feature of the calculation of the scattered fields is the introduction of a new set of modes. As an example, we calculate the reflected and transmitted fields generated by an electromagnetic plane wave that impinges upon a multilayer slab of which the layers are stacked perpendicular to the boundary planes. As this is the geometry of a thick plate with slits our theory encompasses the exact scattering theory of electromagnetic waves by a thick plate with slits.

Intensified partner notification and repeat testing can improve the effectiveness of screening in reducing Chlamydia trachomatis prevalence: a mathematical modelling study.

BACKGROUND The Australian Chlamydia Control Effectiveness Pilot (ACCEPt) was a cluster randomised controlled trial designed to assess the effectiveness of annual chlamydia testing through general practice in Australia. The trial showed that testing rates increased among sexually active men and women aged 16-29 years, but after 3 years the estimated chlamydia prevalence did not differ between intervention and control communities. We developed a mathematical model to estimate the potential longer-term impact of chlamydia testing on prevalence in the general population. METHODS We developed an individual-based model to simulate the transmission of Chlamydia trachomatis in a heterosexual population, calibrated to ACCEPt data. A proportion of the modelled population were tested for chlamydia and treated annually at coverage achieved in the control and intervention arms of ACCEPt. We estimated the reduction in chlamydia prevalence achieved by increasing retesting and by treating the partners of infected individuals up to 9 years after introduction of the intervention. RESULTS Increasing the testing coverage in the general Australian heterosexual population to the level achieved in the ACCEPt intervention arm resulted in reduction in the population-level prevalence of chlamydia from 4.6% to 2.7% in those aged 16-29 years old after 10 years (a relative reduction of 41%). The prevalence reduces to 2.2% if the proportion retested within 4 months of treatment is doubled from the rate achieved in the ACCEPt intervention arm (a relative reduction of 52%), and to 1.9% if the partner treatment rate is increased from 30%, as assumed in the base case, to 50% (a relative reduction of 59%). CONCLUSION A reduction in C. trachomatis prevalence could be achieved if the level of testing as observed in the ACCEPt intervention arm can be maintained at a population level. More substantial reductions can be achieved with intensified case management comprising retesting of those treated and treatment of partners of infected individuals

The center effect in liver transplantation in the Eurotransplant region : a retrospective database analysis

Apart from donor and recipient risk factors, the effect of center-related factors has significant impact on graft survival after liver transplantation (LT). To investigate this effect in Eurotransplant, a retrospective database analysis was performed, including all LT's in adult recipients (18years) in the Eurotransplant region from 1.1.2007 until 31.12.2013. Additionally, a survey was sent out to all transplant centers requesting information on surgeons' experience and exposure. In total, 10265 LT's were included (median follow-up 3.3years), performed in 39 transplant centers. Funnel plots showed significant differences in graft survival between the transplant centers. After correction for donor and recipient risk, with the Eurotransplant donor risk index (ET-DRI) and the simplified recipient risk index (sRRI) and random effects, these differences diminished. Mean historical volume (in the preceding 5years) was a significant (P<0.001), nonlinear marker for graft survival in the multivariate analysis. This study demonstrates that funnel plots can be used for benchmarking purposes in LT. Case-mix correction can be performed with the use of the ET-DRI and sRRI. The center effect encompasses the entire complex process of preoperative workup, operation to follow-up

Agricultural biomass as provisioning ecosystem service: quantification of energy flows

Agro-ecosystems supply provisioning, regulating and cultural services to human society. This study focuses on the agro-ecosystem provisioning services regarding the production of agricultural biomass. These services strongly respond to the socio-economic demands of human beings, and are characterised by an injection of energy in the ecosystems production cycle which is often exceeding the ecological capacity of the ecosystem, i.e. the overall ability of the ecosystem to produce goods and services linked to its bio-physical structure and processes that take place during the agricultural production. Agricultural production is identified as ecosystem service in widely recognised ecosystem service frameworks, but currently there is no clear agreement within the scientific and policy communities on how the ecological-socio-economic flow linked to this provisioning service should be assessed, beyond a mere accounting of yields. This study attempts to provide a new insight to this issue by proposing an approach based on the energy budget, which takes into consideration the energy needed by the ecosystem to supply the service. The approach is based on the concepts of Energy Return on Investment (EROI) and Net Energy Balance (NEB), and considers different bio-physical structures and processes of agroecosystems. The work is structured in three parts: the first aims at estimating inputs (machinery, seeds, fertilizers, irrigation, labour) in energy terms; the second at estimating biomass output in energy terms; the third to compare actual agricultural production with three reference scenarios encompassing a range of human input (no input – low input –high input scenarios). Results show that in general terms cereal and grassland systems have the largest energy gains (both in terms of EROI and NEB). Such systems are characterised by a lower economic value of their output compared to other producing systems such as fruits, which have lower energy gains but a higher embodied energy, which is recognized in the market as valuable. Comparison of actual production systems with the high input scenario confirms that current production in Europe is already highly intensive, and that increasing the energy input would not improve the efficiency of the conversion of such additional energy into biomass. Overall, the proposed approach seems a useful tool to identify which are the factors in the agricultural production process that could be modified to improve the energy efficiency in agricultural systems and the sustainability of their production. This study can be considered as a first step in the assessment of the total energy balance of the agro-ecosystem. In fact it deals with the quantification of energy regarding human inputs and the corresponding output and further analysis should address crucial issues such as the quality of the energy and the embodied energy in the plant production, which will help to better understand the complexity of the agro-ecosystems

Impact of Temporary Portocaval Shunting and Initial Arterial Reperfusion in Orthotopic Liver Transplantation

Perioperative Medicine: Efficacy, Safety and Outcom

Joint modeling of liver transplant candidates outperforms the model for end-stage liver disease: the effect of disease development over time on patient outcome

Liver function is measured regularly in liver transplantation (LT) candidates. Currently, these previous disease development data are not used for survival prediction. By constructing and validating joint models (JMs), we aimed to predict the outcome based on all available data, using both disease severity and its rate of change over time. Adult LT candidates listed in Eurotransplant between 2007 and 2018 (n = 16 283) and UNOS between 2016 and 2019 (n = 30 533) were included. Patients with acute liver failure, exception points, or priority status were excluded. Longitudinal MELD(-Na) data were modeled using spline-based mixed effects. Waiting list survival was modeled with Cox proportional hazards models. The JMs combined the longitudinal and survival analysis. JM 90-day mortality prediction performance was compared to MELD(-Na) in the validation cohorts. MELD(-Na) score and its rate of change over time significantly influenced patient survival. The JMs significantly outperformed the MELD(-Na) score at baseline and during follow-up. At baseline, MELD-JM AUC and MELD AUC were 0.94 (0.92-0.95) and 0.87 (0.85-0.89), respectively. MELDNa-JM AUC was 0.91 (0.89-0.93) and MELD-Na AUC was 0.84 (0.81-0.87). The JMs were significantly (p < .001) more accurate than MELD(-Na). After 90 days, we ranked patients for LT based on their MELD-Na and MELDNa-JM survival rates, showing that MELDNa-JM-prioritized patients had three times higher waiting list mortality.Transplant surger

Development and validation of a dynamic survival prediction model for patients with acute-on-chronic liver failure

Background & aims: Acute-on-chronic liver failure (ACLF) is usually associated with a precipitating event and results in the failure of other organ systems and high short-term mortality. Current prediction models fail to adequately estimate prognosis and need for liver transplantation (LT) in ACLF. This study develops and validates a dynamic prediction model for patients with ACLF that uses both longitudinal and survival data.Methods: Adult patients on the UNOS waitlist for LT between 11.01.2016-31.12.2019 were included. Repeated model for end-stage liver disease-sodium (MELD-Na) measurements were jointly modelled with Cox survival analysis to develop the ACLF joint model (ACLF-JM). Model validation was carried out using separate testing data with area under curve (AUC) and prediction errors. An online ACLF-JM tool was created for clinical application.Results: In total, 30,533 patients were included. ACLF grade 1 to 3 was present in 16.4%, 10.4% and 6.2% of patients, respectively. The ACLF-JM predicted survival significantly (p <0.001) better than the MELD-Na score, both at baseline and during follow-up. For 28- and 90-day predictions, ACLF-JM AUCs ranged between 0.840-0.871 and 0.833-875, respectively. Compared to MELD-Na, AUCs and prediction errors were improved by 23.1%-62.0% and 5%-37.6% respectively. Also, the ACLF-JM could have prioritized patients with relatively low MELD-Na scores but with a 4-fold higher rate of waiting list mortality.Conclusions: The ACLF-JM dynamically predicts outcome based on current and past disease severity. Prediction performance is excellent over time, even in patients with ACLF-3. Therefore, the ACLF-JM could be used as a clinical tool in the evaluation of prognosis and treatment in patients with ACLF.Lay summary: Acute-on-chronic liver failure (ACLF) progresses rapidly and often leads to death. Liver transplantation is used as a treatment and the sickest patients are treated first. In this study, we develop a model that predicts survival in ACLF and we show that the newly developed model performs better than the currently used model for ranking patients on the liver transplant waiting list. (C) 2021 The Author(s). Published by Elsevier B.V.Cellular mechanisms in basic and clinical gastroenterology and hepatolog