Abstract
In this work, we present a novel second-order accurate well-balanced arbitrary Lagrangian–Eulerian (ALE) finite volume scheme on moving nonconforming meshes for the Euler equations of ...compressible gas dynamics with gravity in cylindrical coordinates. The main feature of the proposed algorithm is the capability of preserving many of the physical properties of the system exactly also on the discrete level: besides being conservative for mass, momentum and total energy, also any known steady equilibrium between pressure gradient, centrifugal force, and gravity force can be exactly maintained up to machine precision. Perturbations around such equilibrium solutions are resolved with high accuracy and with minimal dissipation on moving contact discontinuities even for very long computational times. This is achieved by the novel combination of well-balanced path-conservative finite volume schemes, which are expressly designed to deal with source terms written via non-conservative products, with ALE schemes on moving grids, which exhibit only very little numerical dissipation on moving contact waves. In particular, we have formulated a new HLL-type and a novel Osher-type flux that are both able to guarantee the well balancing in a gas cloud rotating around a central object. Moreover, to maintain a high level of quality of the moving mesh, we have adopted a nonconforming treatment of the sliding interfaces that appear due to the differential rotation. A large set of numerical tests has been carried out in order to check the accuracy of the method close and far away from the equilibrium, both, in one- and two-space dimensions.
Obesity has become a major worldwide health problem. In every single country in the world, the incidence of obesity is rising continuously and therefore, the associated morbidity, mortality and both ...medical and economical costs are expected to increase as well. The majority of these complications are related to co-morbid conditions that include coronary artery disease, hypertension, type 2 diabetes mellitus, respiratory disorders and dyslipidemia. Obesity increases cardiovascular risk through risk factors such as increased fasting plasma triglycerides, high LDL cholesterol, low HDL cholesterol, elevated blood glucose and insulin levels and high blood pressure. Novel lipid dependent, metabolic risk factors associated to obesity are the presence of the small dense LDL phenotype, postprandial hyperlipidemia with accumulation of atherogenic remnants and hepatic overproduction of apoB containing lipoproteins. All these lipid abnormalities are typical features of the metabolic syndrome and may be associated to a pro-inflammatory gradient which in part may originate in the adipose tissue itself and directly affect the endothelium. An important link between obesity, the metabolic syndrome and dyslipidemia, seems to be the development of insulin resistance in peripheral tissues leading to an enhanced hepatic flux of fatty acids from dietary sources, intravascular lipolysis and from adipose tissue resistant to the antilipolytic effects of insulin. The current review will focus on these aspects of lipid metabolism in obesity and potential interventions to treat the obesity related dyslipidemia.
In some previous works, the authors have introduced a strategy to develop well-balanced high-order numerical methods for nonconservative hyperbolic systems in the framework of path-conservative ...numerical methods. The key ingredient of these methods is a well-balanced reconstruction operator, i.e. an operator that preserves the stationary solutions in some sense. A strategy has been also introduced to modify any standard reconstruction operator like MUSCL, ENO, CWENO, etc. in order to be well-balanced. In this article, the specific case of 1d systems of balance laws is addressed and difficulties are gradually introduced: the methods are presented in the simpler case in which the source term does not involve Dirac masses. Next, systems whose source term involves the derivative of discontinuous functions are considered. In this case, the notion of weak solution is discussed and the Generalized Hydrostatic Reconstruction technique is used for the treatment of singular source terms. A technique to preserve the well-balancedness of the methods in the presence of numerical integration is introduced. The strategy is applied to derive first, second and third order well-balanced methods for Burgers’ equation with a nonlinear source term and for the Euler equations with gravity.
•The chosen mathematical model is hyperbolic and allows even multivalued free surface profiles.•Well-balanced finite volume scheme for complex nonhydrostatic free surface flows.•Well-balancing is ...achieved via a special reformulation of the Osher Riemann solver.•Efficient implementation in CUDA.
In this paper we propose an efficient second order accurate well balanced finite volume method for modeling complex free surface flows at the aid of a simple diffuse interface method. The employed physical model is a two-phase model directly derived from the Baer–Nunziato system for compressible multi-phase flows. In particular, as proposed for the first time in 1, the number of equations is reduced from seven to three by assuming that the relative pressure of the gas with respect to the atmospheric reference pressure is zero, and that the gas momentum is negligible compared to the one of the liquid. The two-phase model does not make any of the classical assumptions of shallow water type systems, hence it does not neglect vertical accelerations and the free surface is not constraint to be a single-valued function, so even complex shapes as those of breaking waves can be properly captured.
The resulting PDE system is solved by a novel well balanced second order accurate path-conservative finite volume method on structured Cartesian grids, which is able to preserve exactly the equilibrium states even in the presence of obstacles. It furthermore automatically computes the location of the water-air interfaces, and assures low numerical dissipation at the free surface thanks to a novel Osher-Romberg-type approximate Riemann solver. Finally, high computational performance is guaranteed by an efficient parallel implementation on a GPU-based platform that reaches the efficiency of twenty million of volumes processed per seconds and makes it possible to employ even very fine meshes. The validation of our new well balanced scheme is carried out by comparing the obtained numerical results against existing analytical, numerical and experimental reference solutions for a large number of test cases, among which oscillating elliptical drops, dambreak problems, breaking waves, over topping weir flows, and wave impact problems.
•Novel high resolution finite volume schemes on moving nonconforming unstructured meshes.•Significantly improved robustness in shear flows compared to conforming ALE schemes.•Locally and globally ...conservative ALE schemes that respect the geometric conservation law (GCL).•The fully discrete one-step scheme can be derived from a space-time conservation formalism.•Well-balanced for non-trivial stationary solutions of the governing PDE.
In this paper, we present a novel second-order accurate Arbitrary-Lagrangian-Eulerian (ALE) finite volume scheme on moving nonconforming polygonal grids, in order to avoid the typical mesh distortion caused by shear flowsin Lagrangian-type methods. In our new approach the nonconforming element interfaces are not defined by the user, but they are automatically detected by the algorithm if the tangential velocity difference across an element interface is sufficiently large. The grid nodes that are sufficiently far away from a shear wave are moved with a standard node solver, while at the interface we insert a new set of nodes that can slide along the interface in a nonconforming manner. In this way, the elements on both sides of the shear wave can move with a different velocity, without producing highly distorted elements.
The core of the proposed method is the use of a space-time conservation formulation in the construction of the final finite volume scheme, which completely avoids the need of an additional remapping stage, hence the new method is a so-called direct ALE scheme. For this purpose, the governing PDE system is rewritten at the aid of the space-time divergence operator and then a fully discrete one-step discretization is obtained by integrating over a set of closed space-time control volumes. The nonconforming sliding of nodes along an edge requires the insertion or the deletion of nodes and edges, and in particular the space-time faces of an element can be shared between more than two cells.
Due to the space-time conservation formulation, the geometric conservation law (GCL) is automatically satisfied by construction, even on moving nonconforming meshes. Moreover, the mesh quality remains high and, as a direct consequence, also the time step remains almost constant in time, even for highly sheared vortex flows. In this paper we focus mainly on logically straight slip-line interfaces, but we show also first results for general slide lines that are not logically straight. Second order of accuracy in space and time is obtained by using a MUSCL-Hancock strategy, together with a Barth and Jespersen slope limiter.
The accuracy of the new scheme has been further improved by incorporating a special well balancing technique that is able to maintain particular stationary solutions of the governing PDE system up to machine precision. In particular, we consider steady vortex solutions of the shallow water equations, where the pressure gradient is in equilibrium with the centrifugal forces.
A large set of different numerical tests has been carried out in order to check the accuracy and the robustness of the new method for both smooth and discontinuous problems. In particular we have compared the results for a steady vortex in equilibrium solved with a standard conforming ALE method (without any rezoning technique) and with our new nonconforming ALE scheme, to show that the new nonconforming scheme is able to avoid mesh distortion in vortex flows even after very long simulation times.
Abstract Background and Aims Agents that induce an immune response against tumors by altering T-cell regulation have increased survival times of patients with advanced-stage tumors, such as melanoma ...or lung cancer. We aimed to characterize molecular features of immune cells that infiltrate hepatocellular carcinomas (HCCs) to determine whether these types of agents might be effective against liver tumors. Methods We analyzed HCC samples from 956 patients. We separated gene expression profiles from tumor, stromal, and immune cells using a non-negative matrix factorization algorithm. We then analyzed the gene expression pattern of inflammatory cells in HCC tumors samples. We correlated expression patterns with the presence of immune cell infiltrates and immune regulatory molecules, determined by pathology and immunohistochemical analyses, in a training set of 228 HCC samples. We validated the correlation in a validation set of 728 tumor samples. Using data from 190 tumors in the Cancer Genome Atlas, we correlated immune cell gene expression profiles with numbers of chromosomal aberrations (based on single-nucleotide polymorphism array) and mutations (exome sequence data). Results We found approximately 25% of HCCs to have markers of an inflammatory response, with high expression levels of the CD274 molecule (PD-L1) and programmed cell death 1 (PD-1), markers of cytolytic activity, and fewer chromosomal aberrations. We called this group of tumors the Immune class. It contained 2 subtypes, characterized by markers of an adaptive T-cell response or exhausted immune response. The exhausted immune response subclass expressed many genes regulated by transforming growth factor beta 1 (TGFB) that mediate immunosuppression. We did not observe any differences in numbers of mutations or expression of tumor antigens between the immune-specific class and other HCCs. Conclusions In an analysis of HCC samples from 956 patients, we found almost 25% to express markers of an inflammatory response. We identified 2 subclasses, characterized by adaptive or exhausted immune responses. These findings indicate that some HCCs might be susceptible to therapeutic agents designed to block the regulatory pathways in T cells, such as PD-L1, PD-1, or TGFB inhibitors.
Despite being a major public health problem, falls in the elderly cannot be detected efficiently yet. Many studies have used acceleration as the main input to discriminate between falls and ...activities of daily living (ADL). In recent years, there has been an increasing interest in using smartphones for fall detection. The most promising results have been obtained by supervised Machine Learning algorithms. However, a drawback of these approaches is that they rely on falls simulated by young or mature people, which might not represent every possible fall situation and might be different from older people's falls. Thus, we propose to tackle the problem of fall detection by applying a kind of novelty detection methods which rely only on true ADL. In this way, a fall is any abnormal movement with respect to ADL. A system based on these methods could easily adapt itself to new situations since new ADL could be recorded continuously and the system could be re-trained on the fly. The goal of this work is to explore the use of such novelty detectors by selecting one of them and by comparing it with a state-of-the-art traditional supervised method under different conditions. The data sets we have collected were recorded with smartphones. Ten volunteers simulated eight type of falls, whereas ADL were recorded while they carried the phone in their real life. Even though we have not collected data from the elderly, the data sets were suitable to check the adaptability of novelty detectors. They have been made publicly available to improve the reproducibility of our results. We have studied several novelty detection methods, selecting the nearest neighbour-based technique (NN) as the most suitable. Then, we have compared NN with the Support Vector Machine (SVM). In most situations a generic SVM outperformed an adapted NN.
The assessment of pain as the fifth vital sign (P5VS) is of paramount importance since it leads to the management of undertreated pain, consequently reducing suffering, readmissions and emergency ...department visits after hospital discharge.
To evaluate the implementation of P5VS in public and private hospitals.
Data analysis on validated questionnaires was sent to all 171 Portuguese hospitals via an official letter.
When compared to private hospitals, public hospitals presented a higher adherence to the process related to the P5VS. It has demonstrated superiority in the charts properly placed to record P5VS, in the number of emergency departments recording P5VS, in the regularity of audits, and in the existence of guidelines and staff training on pain assessment and management.
The standardization of both evaluation and recording of pain intensity constitutes a measure of good clinical practice. Public hospitals demonstrated better commitment to these procedures that should be properly carried out in all health care institutions.
Cool roofs are an inexpensive method to save energy and to improve the comfort level in buildings in mild and hot climates. A high scale implementation of cool roofs in Andalusia, in the south of ...Spain, could potentially save 295,000 kWh per year, considering only residential buildings with flat roofs using electrical heating. At the current energy prices, consumers can save 59 million euros annually in electricity costs and the emission of 136,000 metric tons of CO2 can be directly avoided every year from the production of that electricity. If radiative forcings are considered, Andalucía can potentially offset between 9.44 and 12 Mt of CO2. All the provinces in the rest of Spain are also studied in this paper. The biggest savings are achieved in Gran Canaria (48%), Tenerife (48%), Cádiz (36%), Murcia (33%), Huelva (30%), Málaga (29%), Almería (29%) and Sevilla (28%), where savings are greater than 2 euros per square meter of flat roof for old buildings with dark roofs. For the biggest cities the range of savings obtained are: between 7.4% and 11% in Madrid, between 12% and 18% in Barcelona and between 14% and 20% in Valencia.
► We estimate potential savings in energy, CO2, and money for cool roofs in Spain (residential sector with flat roofs). ► Average savings are of around one euro per square meter in the biggest cities. ► Potential savings are of more than 2 €/m2 in the hottest cities. ► In Andalusia the potential savings are 300 MWh, 60 millions euro and 136,000 tons of CO2 per year. ► With forcings, the CO2 equivalence of cool roofs in Andalusia is between 9 and 12 Mt.
Summary
High‐order finite volume schemes for conservation laws are very useful in applications, due to their ability to compute accurate solutions on quite coarse meshes and with very few ...restrictions on the kind of cells employed in the discretization. For balance laws, the ability to approximate up to machine precision relevant steady states allows the scheme to compute accurately, also on coarse meshes, small perturbations of such states, which are very relevant for many applications. In this paper, we propose third‐ and fourth‐order accurate finite volume schemes for the shallow water equations. The schemes have the well‐balanced property thanks to a path‐conservative approach applied to an appropriate nonconservative reformulation of the equations. High‐order accuracy is achieved by designing truly two‐dimensional (2D) reconstruction procedures of the central WENO (CWENO) type. The novel schemes are tested for accuracy and well‐balancing and shown to maintain positivity of the water height on wet/dry transitions. Finally, they are applied to simulate the Tohoku 2011 tsunami event.
Novel central WENO (CWENO) reconstructions from cell averages to point values are constructed: we present one third‐order and two and fourth‐order reconstructions that require very small stencils.
Path‐conservative numerical schemes for shallow water equations based on CWENO reconstructions are introduced. The schemes are well balanced, essentially nonoscillatory, preserve the positivity of the water height, and treat correctly the wet/dry transitions.
Applications to the SWE model in both Cartesian and polar coordinates are presented, including a simulation of the Tohoku event.
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