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Double-D2Q9 lattice Boltzmann models with extended equilibrium for two-dimensional magnetohydrodynamic flows
No full textThe vast majority of the existing lattice Boltzmann methods (LBMs) suggest to relax relevant quantities to a second-order truncated equilibrium state. Despite its simplicity and popularity, this choice does not fully exploit the potential of any lattice discretization. In this paper, an extended equilibrium state is adopted to evaluate the suitability of different LBMs (i.e., the Bhatnagar-Gross-Krook, the multiple-relaxation-time in terms of raw and central moments, and the simplified one) to simulate two-dimensional magnetohydrodynamic flows by means of the D2Q9 velocity space. Two sets of particle distribution functions are employed: one for the flow field and the other for the magnetic one. Even if the minimal ve-velocities discretization is sufficient to represent the evolution of the latter, a nine-velocities model enhances the capability to enforce the divergence-free condition of the magnetic field, as shown. Therefore, a double-D2Q9 approach is herein devised. Eventually, the computational cost involved by all the schemes is discussed both in terms of virtual memory and run time. Interestingly, the simplified LBM for magnetohydrodynamic flows is herein presented for the first time
Novel pervaporation-assisted pressure swing reactive distillation process for intensified synthesis of dimethyl carbonate
No full textDimethyl carbonate (DMC) is an environmentally friendly agent with low toxicity and fast biodegradability. DMC synthesis by transesterification of propylene carbonate with methanol has been developed as a cost-efficient option. However, even reactive distillation combined with a series of distillation columns requires significant energy and capital cost. To solve these problems, a novel pervaporation-assisted pressure swing reactive distillation process is proposed in this work as an eco-efficient solution for the transesterification synthesis route. Rigorous simulations were carried out in Aspen Plus, using a custom pervaporation model developed in Aspen Custom Modeler (ACM). Pervaporation (PV) is used for the efficient separation of DMC/MeOH azeotrope, and employs polydimethylsiloxane / polyvinylidene fluoride (PDMS/PVDF) composite membrane. The membrane area is optimized to minimize total annual cost (TAC) of the process. Energy integration by Pinch Analysis was also carried out using Aspen Energy Analyzer to determine the optimal heat exchangers network. The results show that the new intensified PSRD-PV process is more competitive compared with the reference reactive distillation (RD) process reported in literature, allowing about 32% energy savings (due to the ability of PV to separate an azeotrope without distillation), around 42% lower annual cost (1.72 M$ yr-1), as well as largely improved sustainability metrics
Light Curve Calculations for Triple Microlensing Systems
No full textWe present a method to compute the magnification of a finite source star lensed by a triplelens system based on the image boundary (contour integration) method. We describe a newprocedure to obtain continuous image boundaries from solutions of the tenth-order polynomial obtained from the lens equation. Contour integration is then applied to calculate the image areas within the image boundaries, which yields the magnification of a source with uniform brightness. We extend the magnification calculation to limb-darkened stars approximated with a linear profile. In principle, this method works for all multiple lens systems, not just triple lenses. We also include an adaptive sampling and interpolation method for calculating densely covered light curves. The C++ source code and a corresponding Python interface are publicly available
Adverse outcomes associated with rapid linear and non-linear patterns of chronic kidney disease progression
No full textBackground Patients with rapidly declining renal function face the dual threat of end-stage renal disease (ESRD) and mortality prior to ESRD. What is less well characterised is whether the pattern of the renal trajectory, linear or non-linear, unmasks subgroups of rapidly progressing patients that face adverse outcomes in a differential manner. Methods An individual eGFR slope was applied to all outpatient estimated glomerular filtration rate (eGFR) values for each patient in the Salford Kidney Study from 2002 to 2018 who had at least 2years follow-up, ≥4 eGFR values and baseline eGFR 15 to <60ml/min/1.73m2. Rapid progression was defined as an annual eGFR slope of ≤-3ml/min/1.73m2/yr and patients were categorised as linear or non-linear progressors based on the nature of their eGFR-time graphs. A Fine-Gray competing risk hazard model was used to determine factors associated with progression ESRD and with mortality prior to ESRD. Cumulative incidence function curves highlighted differences in outcomes between linear and non-linear patients. Results There were 211 rapidly deteriorating patients with linear eGFR trajectories and 61 rapid non-linear patients in the study cohort. Factors associated with ESRD included younger age, male gender, lower baseline eGFR and higher serum phosphate, whilst older age, history of myocardial infarction and anaemia predicted mortality prior to ESRD. Over a median follow-up of 3.7years, linear progressors reached ESRD sooner whilst those with non-linear progression faced significantly higher rates of mortality prior to ESRD. Conclusions Patients with rapid eGFR decline have high rates of adverse outcomes that are differentially expressed in those progressing linearly and non-linearly as a result of differing phenotypic profiles. Consequently, addressing individual risk factor profiles is important to deliver optimal personalised patient care
NERO: A Biomedical Named-entity (Recognition) Ontology with a Large, Annotated Corpus Reveals Meaningful Associations Through Text Embedding
No full textMachine reading is essential for unlocking valuable knowledge contained in millions of existing biomedical documents. Over the last two decades, the most dramatic advances in machine-reading have followed in the wake of critical corpus development1 Large, well-annotated corpora have been associated with punctuated advances in machine reading methodology and automated knowledge extraction systems in the same way that ImageNet 2 was fundamental for developing machine vision techniques. This study contributes six components to an advanced, named-entity analysis tool for biomedicine: (a) a new, Named Entity Recognition Ontology (NERO) developed specifically for describing textual entities in biomedical texts, which accounts for diverse levels of ambiguity, bridging the scientific sublanguages of molecular biology, genetics, biochemistry, and medicine; (b) detailed guidelines for human experts annotating hundreds of named-entity classes; (c) pictographs for all named entities, to simplify the burden of annotation for curators; (d) an original, annotated corpus comprising 35,865 sentences, which encapsulate 190,679 named entities and 43,438 events connecting two or more entities; (e) validated, off-the-shelf, named entity recognition automated extraction, and; (f) embedding models that demonstrate the promise of biomedical associations embedded within this corpus
Impact of weld restraint on the development of distortion and stress during the electron beam welding of a low-alloy steel subject to solid state phase transformation
No full textElectron beam (EB) welding has a low tolerance to inter-part gapping distortion and can generate complicated stresses, which pose challenges to weld quality and integrity. This study investigates welding distortion and stresses in an EB welded plate made from SA508 Grade 4N low-alloy steel. A thermal-metallurgical-mechanical model was developed to predict the temperature, micro-constituents, hardness, distortion and stresses in the EB weldment; the predictions are in good agreement with experimental results. Different restraint conditions on the weld plane were modelled to examine their effects on distortion and stresses. If welding is performed with no restraint, inter-part gapping develops ahead of the beam position that could exceed the tolerance for a sound weld. In contrast, tack welds at the plate ends significantly reduce this gapping, but induce additional tensile stress at the stop-end tack weld. This stress is particularly high as the beam approaches the tack weld. Increasing the extent of the tack welds reduces the tensile stress, while increasing number of distantly distributed narrow tack welds does not help. A full through-length restraint eliminates the opening gap and minimises the development of tensile stresses ahead of the beam that could potentially break the restraint. The applied restraint on the weld plane has little effect on the final residual stress field, since this field mostly develops during cooling after the EB weld is complete. The weld-induced martensitic transformation suppressed tension or promoted compression in the EB weld and heat affected zone (HAZ). A steep gradient of residual stress exists, with high tensile stress concentrated in a narrow region immediately outside the HAZ
Five year follow-up on the prevalence and intensity of infections of Schistosoma mansoni in a hard-to-reach district of Madagascar
No full textSchistosomiasis is a major public health problem in Madagascar. World Health Organization recommends preventive chemotherapy by mass drug administration (MDA) with praziquantel as the primary approach to control Schistosoma mansoni related morbidity in endemic populations, alongside complementary interventions such as health education. The impact of annual MDA and health education programs was assessed in the hard-to-reach Marolambo District of eastern Madagascar, an area endemic for S. mansoni. Repeated cross-sectional studies undertaken 2015–2019 examined between 300 and 381 school-aged children (aged 5–14 years) annually. The prevalence and infection intensity of S. mansoni were assessed by urine-circulating cathodic antigen (CCA) dipsticks and coproscopy using Kato-Katz (KK) methodologies. After four rounds of annual MDA, a reduction in S. mansoni prevalence was seen in CCA (93.9% in Year 1 to 87.7% in Year 5; p=0.007) and KK (73.9% in Year 1 to 59.4% in Year 5; p<0.0001). Prevalence of heavy-intensity infections roughly halved from 23.7% to 10.1% (p<0.0001), and the mean intensity of infection fell by 55.0% (480.2 to 216.3 eggs per gram of feces). A malacological survey found Biomphalaria pfeifferi snail intermediate hosts in multiple water contact sites including rice paddies, streams and Nosivolo River. Despite reductions in infection prevalence and intensity, schistosomiasis still poses a significant public health challenge in Marolambo District. Twice yearly MDA cycles and/or community-wide MDA are suggested to better reduce infections. Expanding health education, improving standards of water, sanitation and hygiene, and attention on snail-related control will also be important, especially in rice paddy irrigated areas
E2 enzymes in genome stability: pulling the strings behind the scenes
No full textUbiquitin and ubiquitin-like proteins (UBLs) function as critical post-translational modifiers in the maintenance of genome stability. Ubiquitin/UBL-conjugating enzymes (E2s) are responsible, as part of a wider enzymatic cascade, for transferring single moieties or poly-chains of ubiquitin/UBLs to one or multiple residues on substrate proteins. Recent advances in structural and mechanistic understanding of how ubiquitin/UBL substrate attachment is orchestrated indicate that E2s can exert control over chain topology, substrate-site specificity and downstream physiological effects to help maintain genome stability. Drug discovery efforts have typically focussed on modulating other members of the ubiquitin/UBL cascades, or the ubiquitin-proteasome system. Here, we review the current standing of E2s in genome stability and revisit their potential as pharmacological targets for developing novel anti-cancer therapies
An Efficient Augmented Lagrange Multiplier Method for Steelmaking and Continuous Casting Production Scheduling
No full textThe steelmaking and continuous casting (SCC) process is one of the vital processes in iron and steel plants since it determines chemical compositions of slabs and is often a bottleneck for iron and steel manufacturing. In this paper, we first develop a discrete-time mixed-integer linear programming (MILP) formulation for a new SCC scheduling problem where different processing routes are used to produce diversified and personalized slab products. To solve the proposed MILP formulation efficiently, we then propose a novel efficient solution algorithm using Augmented Lagrange multiplier method (e-ALM) through relaxation of the coupling constraints and incorporation of penalty components. A heuristic-based list scheduling approach as well as adjacent pairwise swap operations is used to construct a high-quality feasible schedule. A fine-adjusting strategy based on the subgradient direction is proposed to update Lagrangian multipliers dynamically to speed up the convergence. It is shown that the proposed e-ALM is able to generate optimal or near-optimal solutions with 5% optimality for 150 industrial-scale instances and outperform the commercial solver GAMS/CPLEX and the existing Lagrangian relaxation algorithms with better feasible solutions and smaller duality gap within the specified computational time