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- Ademuyiwa, Adesoji O., et al.
(author)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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In: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Journal article (peer-reviewed)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Thomas, HS, et al.
(author)
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- 2019
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swepub:Mat__t
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| 4. |
- Richardson, Omar, et al.
(author)
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Parallel two-scale finite element implementation of a system with varying microstructures
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Other publication (other academic/artistic)abstract
- We propose a two-scale finite element method designed for heterogeneous microstructures. Our approach exploits domain diffeomorphisms between the microscopic structures to gain computational efficiency.By using a conveniently constructed pullback operator, we are able to model the different microscopic domains as macroscopically dependent deformations of a reference domain.This allows for a relatively simple finite element framework to approximate the underlying PDE system with a parallel computational structure.We apply this technique to a model problem where we focus on transport in plant tissues.We illustrate the accuracy of the implementation with convergence benchmarks and show satisfactory parallelization speed-ups.We further highlight the effect of the heterogeneous microscopic structure on the output of the two-scale systems.Our implementation (publicly available on GitHub) builds on the deal.II FEM library.Application of this technique allows for an increased capacity of microscopic detail in multiscale modeling, while keeping running costs manageable.
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| 5. |
- Beentjes, Casper, et al.
(author)
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Equalizing the Cost of Health Insurance
- 2017
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In: Proceedings of the 126th European Study GroupMathematics with Industry. - : SWI. ; , s. 29-49
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Conference paper (other academic/artistic)abstract
- The Dutch government compensates health insurance companies when insuringindividuals who are estimated to have high health care costs. This is necessaryto avoid insurers not offering services to certain groups or not providing themwith a high quality of service. It is, however, unknown to what extent thedifferences in health care expenses by different groups of people are truly due toa poorer or better health status. We explore several statistical approaches thatfacilitate explaining the cause of these differences.
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| 7. |
- Cirillo, Emilio, et al.
(author)
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Deterministic model of battery, uphill currents and non-equilibrium phase transitions
- 2021
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In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society. - 1063-651X .- 1095-3787. ; 103:3
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Journal article (peer-reviewed)abstract
- We consider point particles in a table made of two circular cavities connected by two rectangular channels, forming a closed loop under periodic boundary conditions. In the first channel, a bounce-back mechanism acts when the number of particles flowing in one direction exceeds a given threshold T. In that case, the particles invert their horizontal velocity, as if colliding with vertical walls. The second channel is divided in two halves parallel to the first but located in the opposite sides of the cavities. In the second channel, motion is free. We show that, suitably tuning the sizes of cavities of the channels and of T, nonequilibrium phase transitions take place in the N→∞ limit. This induces a stationary current in the circuit, thus modeling a kind of battery, although our model is deterministic, conservative, and time reversal invariant.
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| 8. |
- Cirillo, Emilio N.M., et al.
(author)
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Deterministic reversible model of non-equilibrium phase transitions and stochastic counterpart
- 2020
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In: Journal of Physics A. - : Institute of Physics (IOP). - 1751-8113 .- 1751-8121. ; 53:30
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Journal article (peer-reviewed)abstract
- Npoint particles move within a billiard table made of two circular cavities connected by a straight channel. The usual billiard dynamics is modified so that it remains deterministic, phase space volumes preserving and time reversal invariant. Particles move in straight lines and are elastically reflected at the boundary of the table, as usual, but those in a channel that are moving away from a cavity invert their motion (rebound), if their number exceeds a given thresholdT. When the geometrical parameters of the billiard table are fixed, this mechanism gives rise to non-equilibrium phase transitions in the largeNlimit: lettingT/Ndecrease, the homogeneous particle distribution abruptly turns into a stationary inhomogeneous one. The equivalence with a modified Ehrenfest two urn model, motivated by the ergodicity of the billiard with no rebound, allows us to obtain analytical results that accurately describe the numerical billiard simulation results. Thus, a stochastic exactly solvable model that exhibits non-equilibrium phase transitions is also introduced.
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| 9. |
- Cirillo, E. N. M., et al.
(author)
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Upscaling the interplay between diffusion and polynomial drifts through a composite thin strip with periodic microstructure
- 2020
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In: Meccanica (Milano. Print). - : Springer. - 0025-6455 .- 1572-9648. ; 55:11, s. 2159-2179
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Journal article (peer-reviewed)abstract
- We study the upscaling of a system of many interacting particles through a heterogenous thin elongated obstacle as modeled via a two-dimensional diffusion problem with a one-directional nonlinear convective drift. Assuming that the obstacle can be described well by a thin composite strip with periodically placed microstructures, we aim at deriving the upscaled model equations as well as the effective transport coefficients for suitable scalings in terms of both the inherent thickness at the strip and the typical length scales of the microscopic heterogeneities. Aiming at computable scenarios, we consider that the heterogeneity of the strip is made of an array of periodically arranged impenetrable solid rectangles and identify two scaling regimes what concerns the small asymptotics parameter for the upscaling procedure: the characteristic size of the microstructure is either significantly smaller than the thickness of the thin obstacle or it is of the same order of magnitude. We scale up the diffusion-polynomial drift model and list computable formulas for the effective diffusion and drift tensorial coefficients for both scaling regimes. Our upscaling procedure combines ideas of two-scale asymptotics homogenization with dimension reduction arguments. Consequences of these results for the construction of more general transmission boundary conditions are discussed. We illustrate numerically the concentration profile of the chemical species passing through the upscaled strip in the finite thickness regime and point out that trapping of concentration inside the strip is likely to occur in at least two conceptually different transport situations: (i) full diffusion/dispersion matrix and nonlinear horizontal drift, and (ii) diagonal diffusion matrix and oblique nonlinear drift.
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