Improving the accuracy of the mini-element approximation to Navier-Stokes equations

^** Email: blanca{at}imati.cnr.it^*** Email: frutos{at}mac.cie.uva.es^**** Corresponding author. Email: julia.novo{at}uam.es A technique to improve the accuracy of the mini-element approximationto incompressible the Navier–Stokes equations is introduced.Once the mini-element approximation has been computed at a fixedtime, the linear part of this approximation is postprocessedby solving a discrete Stokes problem. The bubble functions neededto stabilize the approximation to the Navier–Stokes equationsare not used at the postprocessing step. This postprocessingprocedure allows us to increase by one unit (up to a logarithmicterm) the H¹ norm rate of convergence of the velocity and correspondinglythe L² norm of the pressure. An error analysis of the algorithmis performed.     

Chemical modification of the adeno-associated virus capsid to improve gene delivery

Gene delivery vectors based on adeno-associated virus (AAV) are highly promising due to several desirable features of this parent virus, including a lack of pathogenicity, efficient infection of dividing and non-dividing cells and sustained maintenance of the viral genome. However, the conclusion from clinical data using these vectors is that there is a need to develop new AAVs with a higher transduction efficiency and specificity for relevant target tissues. To overcome these limitations, we chemically modified the surface of the capsid of AAV vectors. These modifications were achieved by chemical coupling of a ligand by the formation of a thiourea functionality between the amino group of the capsid proteins and the reactive isothiocyanate motif incorporated into the ligand. This strategy does not require genetic engineering of the capsid sequence. The proof of concept was first evidenced using a fluorophore (FITC). Next, we coupled the N-acetylgalactosamine ligand onto the surface of the AAV capsid for asialoglycoprotein receptor-mediated hepatocyte-targeted delivery. Chemically-modified capsids also showed reduced interactions with neutralizing antibodies. Taken together, our findings reveal the possibility of creating a specific engineered platform for targeting AAVs via chemical coupling.

Bioconjugated AAV vectors, achieved by coupling of ligands on amino groups of the capsid, are of great interest for gene delivery. Chemical modifications can be used to enhance cell tropism and to decrease interactions with neutralizing antibodies.     

Use of N‐methyliminodiacetic acid boronate esters in suzuki‐miyaura cross‐coupling polymerizations of triarylamine and fluorene monomers

Polytriarylamine copolymers can be prepared by Suzuki‐Miyaura cross‐coupling reactions of bis N‐methyliminodiacetic acid (MIDA) boronate ester substituted arylamines with dibromo arenes. The roles of solvent composition, temperature, reaction time, and co‐monomer structure were examined and (co)polymers prepared containing 9, 9‐dioctylfluorene (F8), 4‐sec‐butyl or 4‐octylphenyl diphenyl amine (TFB), and N, N′‐bis(4‐octylphenyl)‐N, N′‐diphenyl phenylenediamine (PTB) units, using a Pd(OAc)₂/2‐dicyclohexylphosphino‐2′,6′‐dimethoxybiphenyl (SPhos) catalyst system. The performance of a di‐functionalized MIDA boronate ester monomer was compared with that of an equivalent pinacol boronate ester. Higher molar mass polymers were produced from reactions starting with a difunctionalized pinacol boronate ester monomer than the equivalent difunctionalized MIDA boronate ester monomer in biphase solvent mixtures (toluene/dioxane/water). Matrix‐assisted laser desorption/ionization mass spectroscopic analysis revealed that polymeric structures rich in residues associated with the starting MIDA monomer were present, suggesting that homo‐coupling of the boronate ester must be occurring to the detriment of cross‐coupling in the step‐growth polymerization. However, when comparable reactions of the two boronate monomers with a dibromo fluorene monomer were completed in a single phase solvent mixture (dioxane + water), high molar mass polymers with relatively narrow distribution ranges were obtained after only 4 h of reaction. © 2017 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2798–2806     

L2‐estimates for the DG IIPG‐0 scheme

We discuss the optimality in L² of a variant of the Incomplete Discontinuous Galerkin Interior Penalty method (IIPG) for second order linear elliptic problems. We prove optimal estimate, in two and three dimensions, for the lowest order case under suitable regularity assumptions on the data and on the mesh. We also provide numerical evidence, in one dimension, of the necessity of the regularity assumptions. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2012     

Strategies for detecting fraudulent claims in the automobile insurance industry

Some property and casualty insurers use automated detection systems to help to decide whether or not to investigate claims suspected of fraud. Claim screening systems benefit from the coded experience of previously investigated claims. The embedded detection models typically consist of scoring devices relating fraud indicators to some measure of suspicion of fraud. In practice these scoring models often focus on minimizing the error rate rather than on the cost of (mis)classification. We show that focusing on cost is a profitable approach. We analyse the effects of taking into account information on damages and audit costs early on in the screening process. We discuss several scenarios using real-life data. The findings suggest that with claim amount information available at screening time detection rules can be accommodated to increase expected profits. Our results show the value of cost-sensitive claim fraud screening and provide guidance on how to render this strategy operational.     

Efficient extraction of PAHs in aqueous organised media assisted by focused microwaves

Summary A novel method for the extraction into an aqueous medium of PAHs in soil is described, where sodium dodecyl sulphate (SDS) is used as micelle former. After optimisation of this step using a multivariate approach, recoveries of the target analytes from spiked soil ranging between 98.3%–99.7% were obtained when the samples were subjected to extraction with 25 mL of an aqueous SDS solution (2.9 10⁻² mol L⁻¹) while irradiated with focused microwaves at 240 W for 40 min. The overall method involving determination of the extracted compounds consists of three steps: 1) extraction of the analytes into the aqueous micellar medium assisted by focused microwaves; 2) trapping of the analytes on a C₁₈ cartridge for clean up and preconcentration and; 3) HPLC separation with fluorimetric detection. The method was validated using the certified reference material CRM 524 and the results found were in agreement with the certified values.     

CMMSE-17: general analytical laws for metabolic pathways

In this paper a general formulation for the kinetics of multi-step enzymatic reactions is presented. The optimal enzyme and metabolite concentrations are studied for the problem of minimizing the operation time in which the substrate is converted into the product. We give an analytic solution for three different kinetic models for both the unbranched and branched cases. Sufficient conditions for the optimality of the solution are studied. Several examples are presented.