A moving mesh method for one-dimensional hyperbolic conservation laws

We develop an adaptive method for solving one-dimensional systems of hyperbolic conservation laws that employs a high resolution Godunov-type scheme for the physical equations, in conjunction with a moving mesh PDE governing the motion of the spatial grid points. Many other moving mesh methods developed to solve hyperbolic problems use a fully implicit discretization for the coupled solution-mesh equations, and so suffer from a significant degree of numerical stiffness. We employ a semi-implicit approach that couples the moving mesh equation to an efficient, explicit solver for the physical PDE, with the resulting scheme behaving in practice as a two-step predictor-corrector method. In comparison with computations on a fixed, uniform mesh, our method exhibits more accurate resolution of discontinuities for a similar level of computational work

The Pendulum Swings Back: Revisiting Corporate Criminality and the Rise of Deferred Prosecution Agreements

Essay from the Project for Law and Business Ethics Symposium: “Unearthing Corporate Wrongdoing: Detecting and Dealing with Ethical Breaches in the Business World

Building forests for the future

Many governments have set ambitious targets for tree planting and increased woodland cover as a key part of actions to reach net‐zero carbon emissions by 2050. However, many uncertainties remain concerning how and where to expand tree cover, what species to plant, and how best to manage new plantations. Much contemporary forestry has been based on even‐aged monocultures, largely because of perceived advantages for timber production. However, in order to play a key role in climate change mitigation future forests will have to achieve timber production (and wider ecosystem service provision) alongside resilience to biotic and abiotic challenge. It is therefore crucial that appropriate informed decisions are made with regard to the structure, composition, and planning of future forests, in order to provide sustainable solutions that provide environmental, economic, and health benefits to society. Genetically diverse, mixed, and irregular forests, with their higher biodiversity and niche complementarity, are promising new forest configurations for regulating the water cycle, storing carbon, and delivering other goods and services. In the following discussion, we have used UK information to illustrate the benefits of mixed woodland versus monocultures and highlighted current issues related to government initiatives and policies for current and future forests. However, similar issues and problems are encountered globally

Building forests for the future

Many governments have set ambitious targets for tree planting and increased woodland cover as a key part of actions to reach net‐zero carbon emissions by 2050. However, many uncertainties remain concerning how and where to expand tree cover, what species to plant, and how best to manage new plantations. Much contemporary forestry has been based on even‐aged monocultures, largely because of perceived advantages for timber production. However, in order to play a key role in climate change mitigation future forests will have to achieve timber production (and wider ecosystem service provision) alongside resilience to biotic and abiotic challenge. It is therefore crucial that appropriate informed decisions are made with regard to the structure, composition, and planning of future forests, in order to provide sustainable solutions that provide environmental, economic, and health benefits to society. Genetically diverse, mixed, and irregular forests, with their higher biodiversity and niche complementarity, are promising new forest configurations for regulating the water cycle, storing carbon, and delivering other goods and services. In the following discussion, we have used UK information to illustrate the benefits of mixed woodland versus monocultures and highlighted current issues related to government initiatives and policies for current and future forests. However, similar issues and problems are encountered globally

Multiscale modelling of drug-polymer nanoparticle assembly identifies parameters influencing drug encapsulation efficiency

Using a multiscale (dual resolution) approach combining an atomistic (GROMOS96) and coarse-grain (MARTINI) force field, we have been able to simulate the process of drug-polymer nanoparticle assembly by nanoprecipitation from mixed solvents. Here we present the development and application of this method to the interaction of three poly(glycerol adipate) polymer variants with the anti-cancer drug dexamethasone phosphate. Differences in encapsulation efficiency and drug loading between the polymers are in agreement with the experimental trend. Reference atomistic simulations at key points along the predicted aggregation pathway support the accuracy of the much more compute-efficient multiscale methodology

The effect of selective phosphodiesterase inhibitors, alone and in combination, on a murine model of allergic asthma

BACKGROUND: The anti-inflammatory effects of the selective phosphodiesterase (PDE) inhibitors cilostazol (PDE 3), RO 20-1724 (PDE 4) and sildenafil (PDE 5) were examined in a murine model of allergic asthma. These compounds were used alone and in combination to determine any potential synergism, with dexamethasone included as a positive control. METHODS: Control and ovalbumin sensitised Balb/C mice were administered orally with each of the possible combinations of drugs at a dose of 3 mg/Kg for 10 days. RESULTS: When used alone, RO 20-1724 significantly reduced eosinophil influx into lungs and lowered tumour necrosis factor-α, interleukin-4 and interleukin-5 levels in the bronchoalveolar lavage fluid when compared to untreated mice. Treatment with cilostazol or sildenafil did not significantly inhibit any markers of inflammation measured. Combining any of these PDE inhibitors produced no additive or synergistic effects. Indeed, the anti-inflammatory effects of RO 20-1724 were attenuated by co-administration of either cilostazol or sildenafil. CONCLUSIONS: These results suggest that concurrent treatment with a PDE 3 and/or PDE 5 inhibitor will reduce the anti-inflammatory effectiveness of a PDE 4 inhibitor

New York State: Comparison of Treatment Outcomes for Unruptured Cerebral Aneurysms Using an Instrumental Variable Analysis

Background: There is wide regional variation in the predominant treatment for unruptured cerebral aneurysms. We investigated the association of elective surgical clipping and endovascular coiling with mortality, readmission rate, length of stay, and discharge to rehabilitation. Methods and Results: We performed a cohort study involving patients with unruptured cerebral aneurysms, who underwent surgical clipping or endovascular coiling from 2009 to 2013 and were registered in the Statewide Planning and Research Cooperative System database. An instrumental variable analysis was used to investigate the association of treatment technique with outcomes. Of the 4643 patients undergoing treatment, 3190 (68.7%) underwent coiling, and 1453 (31.3%) underwent clipping. Using an instrumental variable analysis, we did not identify a difference in inpatient mortality (marginal effect, 0.13; 95% CI, −0.30, 0.57), or the rate of 30‐day readmission (marginal effect, −1.84; 95% CI −4.06, −0.37) between the 2 treatment techniques for patients with unruptured cerebral aneurysms. Clipping was associated with a higher rate of discharge to rehabilitation (marginal effect, 2.31; 95% CI 0.21, 4.41), and longer length of stay (β, 2.01; 95% CI 0.85, 3.04). In sensitivity analysis, mixed‐effect regression, and propensity score, adjusted regression models demonstrated identical results. Conclusions: Using a comprehensive all‐payer cohort of patients in New York State with unruptured cerebral aneurysms, we did not identify an association of treatment method with mortality or 30‐day readmission. Clipping was associated with a higher rate of discharge to rehabilitation and longer length of stay