Three-dimensional instabilities and transient growth of a counter-rotating vortex pair

International audienceThis paper investigates the three-dimensional instabilities and the transient growth of perturbations on a counter-rotating vortex pair. The two dimensional base flow is obtained by a direct numerical simulation initialized by two Lamb-Oseen vortices that quickly adjust to a flow with elliptic vortices. In the present study, the Reynolds number,ReΓ=Γ/ν, with Γ the circulation of one vortex and ν the kinematic viscosity, is taken large enough for the quasi steady assumption to be valid. Both the direct linearized Navier-Stokes equation and its adjoint are solved numerically and used to investigate transient and long time dynamics. The transient dynamics is led by different regions of the flow, depending on the optimal time considered. At very short times compared to the advection time of the dipole, the dynamics is concentrated on the points of maximal strain of the base flow, located at the periphery of the vortex core. At intermediate times, depending on the symmetry of the perturbation, one of the hyperbolic stagnation points provides the optimal amplification by stretching of the perturbation vorticity as in the classical hyperbolic instability. The growth of both short time and intermediate time transient perturbations are non- or weakly dependent of the axial wavenumber whereas the long time behavior strongly selects narrow bands of wavenumbers. We show that, for all unstable spanwise wavenumbers, the transient dynamics last until the nondimensional time t=2, during which the dipole has traveled twice the separation distance between vorticesb. During that time, all the wavenumbers exhibit a transient growth of energy by a factor of 50, for the Reynolds numberReΓ=2000. For time larger than t=2, energy starts growing at a rate given by the standard temporal stability theory. For all wavenumbers and two Reynolds numbers,ReΓ=2000 and ReΓ=105, different instability branches have been computed using a high resolution Krylov method. At large Reynolds number, the computed Crow and elliptic instability branches are in excellent agreement with the inviscid theory [S. C. Crow, AIAA J.8, 2172 (1970); S. Le Dizes and F. Laporte, J. Fluid Mech.471, 120 (2002)] and numerical analysis [D. Sipp and L. Jacquin, Phys. Fluids15, 1861 (2003)]. A novel oscillatory elliptic instability involving Kelvin waves with azimuthal wavenumbers m=0 and |m|=2, that was missed in previous numerical analysis [D. Sipp and L. Jacquin, Phys. Fluids15, 1861 (2003)] is found. For the stationary elliptic instability, we show that viscous effect may be estimated using the large Reynolds number direct and adjoint eigenmodes. This asymptotically exact estimate of the viscous damping of elliptic instability mode agrees with our direct numerical computation of instability branches at moderate Reynolds number and demonstrates that formula proposed by Le Dizes and Laporte [J. Fluid Mech.471, 120 (2002)] strongly over estimated the viscous correction

Designing bioactive porous titanium interfaces to balance mechanical properties and in vitro cells behavior towards increased osseointegration

Titanium implant failures are mainly related to stress shielding phenomenon and the poor cell interaction with host bone tissue. The development of bioactive and biomimetic Ti scaffolds for bone regeneration remains a challenge which needs the design of Ti implants with enhanced osseointegration. In this context, 4 types of titanium samples were fabricated using conventional powder metallurgy, fully dense, dense etched, porous Ti, and porous etched Ti. Porous samples were manufactured by space holder technique, using ammonium bicarbonate particles as spacer in three different ranges of particle size (100–200 μm, 250–355 μm and 355–500 μm). Substrates were chemically etched by immersion in fluorhydric acid at different times (125 and 625 s) and subsequently, were characterized from a micro-structural, topographical and mechanical point of view. Etched surfaces showed an additional roughness preferentially located inside pores. In vitro tests showed that all substrates were biocompatible (80% of cell viability), confirming cell adhesion of premioblastic cells. Similarly, osteoblast showed similar cell proliferation rates at 4 days, however, higher cell metabolic activity was observed in fully dense and dense etched surfaces at 7 days. In contrast, a significant increase of alkaline phosphatase enzyme expression was observed in porous and porous etched samples compared to control surfaces (dense and dense etched), noticing the suitable surface modification parameters (porosity and roughness) to improve cell differentiation. Furthermore, the presence of pores and rough surfaces of porous Ti substrates remarkably decreased macrophage activation reducing the M1 phenotype polarization as well M1 cell marker expression. Thus, a successful surface modification of porous Ti scaffolds has been performed towards a reduction on stress shielding phenomenon and enhancement of bone osseointegration, achieving a biomechanical and biofunctional equilibrium.Ministry of Economy and Competitiveness of Spain grant MAT2015-71284-PJunta de Andalucía – FEDER (Spain) Project Ref. P12-TEP-140

Formulación de un plan de direccionamiento estratégico para la empresa de cobranzas y asesorías empresariales GCA Ltda. para el periodo 2019-2024

Uno de los problemas que impide a las empresas orientarse hacia una mejor posición futura, es la creencia errada de que el modo como en la actualidad desarrollan sus actividades administrativas, productivas, comerciales, logísticas de publicidad y mercadeo etc., son las ideales y por tanto no merecen una revisión a nivel estratégico. Los autores del presente trabajo de investigación han podido reconocer la situación actual de la empresa GCA Ltda., una empresa dedicada a la recuperación de cartera, "un servicio dirigido a aquellas empresas y organizaciones que requieran de manera urgente rescatar su inversión" (GCA Ltda, 2017), tal oferta de valor se ha venido complementando a lo largo del tiempo con otros productos que se suman a su portafolio de servicios. Dada la multiplicidad de servicios prestados por la empresa, se puede identificar que la gerencia apunta a una gran diversidad de necesidades del mercado, un proceso que posiblemente se ha ido fortaleciendo dada la estrecha confianza que las empresas le depositan; sin embargo tal variedad de servicios no permite identificar claramente una diferenciación entre los mismos, situación que podría interpretar la necesidad de una intervención a manera de direccionamiento estratégico, a partir de un adecuado análisis interno y del entorno.PregradoADMINISTRADOR(A) DE EMPRESA

Directed Irradiation Synthesis as an Advanced Plasma Technology for Surface Modification to Activate Porous and “as-received” Titanium Surfaces

For the design of smart titanium implants, it is essential to balance the surface properties without any detrimental effect on the bulk properties of the material. Therefore, in this study, an irradiation-driven surface modification called directed irradiation synthesis (DIS) has been developed to nanopattern porousand“as-received”c.p. Tisur faces with the aim of improving cellular viability. Nano features were developed using singly-charged argon ions at 0.5 and 1.0 keV energies, incident angles from 0◦ to 75◦ degrees, and fluences up to 5.0×1017 cm−2. Irradiated surfaces were evaluated by scanning electron microscopy, atomic force microscopy and contact angle, observing an increased hydrophilicity (a contact angle reduction of 73.4% and 49.3%) and a higher roughness on both surfaces except for higher incident angles, which showed the smoothest surface. In-vitro studies demonstrated the biocompatibility of directed irradiation synthesis (DIS) reaching 84% and 87% cell viability levels at 1 and 7 days respectively, and a lower percentage of damaged DNA in tail compared to the control c.p. Ti. All these results confirm the potential of the DIS technique to modify complex surfaces at the nanoscale level promoting their biological performance.Department of Defense (Spain) contract W81XWH-11-2-0067Ministry of Economy and Competitiveness of Spain grant MAT2015-71284-

THBD sequence variants potentially related to recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a frequently occurring disease, which is classified as idiopathic in more than 50% of cases. THBD, the endothelial cell receptor for thrombin, has been associated with distinct biological processes and considered a coherent RPL-related candidate gene. In the present study, we have sequenced the complete coding region of THBD in 262 patients affected by RPL. Bioinformatics analysis and screening of controls strongly suggested that the THBD-p.Trp153Gly mutation might be related to RPL aetiology. It could be used, after its validation by functional assays, as a molecular marker for diagnostic/prognostic purposes. © 2017 The Author(s)

Greenhouse gas emission reduction in residential buildings: A lightweight model to be deployed on edge devices

Keywords Greenhouse gas emission; Energy efficiency; Photovoltaics; Battery; Edge computing; Linear programming Electricity produced and used in the residential sector is responsible for approximately 30% of the greenhouse gas emissions (GHGE). Insulating houses and integrating renewable energy and storage resources are key for reducing such emissions. However, it is not only a matter of installing renewable energy technologies but also of optimizing the charging/discharging of the storage units. A number of optimization models have been proposed lately to address this problem. However, they are often limited in several respects: (i) they often focus only on electricity bill reduction, placing GHGE reduction on the backburner; (ii) they rarely propose hybrid-energy storage optimization strategies considering thermal and storage heater units; (iii) they are often designed using Linear Programming (LP) or metaheuristic techniques that are computational intensive, hampering their deployment on edge devices; and (iv) they rarely evaluate how the model impacts on the battery lifespan. Given this state-of-affairs, the present article compares two approaches, the first one proposing an innovative sliding grid carbon intensity threshold algorithm developed as part of a European project named RED WoLF, the second one proposing an algorithm designed based on LP. The comparison analysis is carried out based on two distinct real-life scenarios in France and UK. Results show that both algorithms contribute to reduce GHGE compared to a solution without optimization logic (between 10 to 25%), with a slight advantage for the LP algorithm. However, RED WoLF makes it possible to reduce significantly the computational time ([almost equal to]25 min for LP against [almost equal to]1 ms for RED WoLF) and to extend the battery lifespan (4 years for LP against 12 years for RED WoLF). Author Affiliation: (a) Université de Lorraine, CNRS, CRAN, F-54000, France (b) Interdisciplinary Centre for Security, Reliability and Trust, University of Luxembourg, L-1359 Esch-sur-Alzette, Luxembourg (c) Department of Industrial and Systems Engineering, Rochester Institute of Technology, 81 Lomb Memorial Drive, Rochester, NY 14623, United States (d) School of Built Environment, Engineering and Computing, Leeds Beckett University, Leeds, LS1 3HE, UK * Corresponding author. Article History: Received 12 March 2022; Revised 3 June 2022; Accepted 8 July 2022 (miscellaneous) Handling Editor: Panos Seferlis Byline: Paul Ortiz [[email protected]] (a,*), Sylvain Kubler [[email protected]] (a,b), Éric Rondeau [[email protected]] (a), Katie McConky [[email protected]] (c), Alexander Alexandrovich Shukhobodskiy [[email protected]] (d), Giuseppe Colantuono [[email protected]] (d), Jean-Philippe Georges [[email protected]] (a

Accurate quantification of atherosclerotic plaque volume by 3D vascular ultrasound using the volumetric linear array method.

Direct quantification of atherosclerotic plaque volume by three-dimensional vascular ultrasound (3DVUS) is more reproducible than 2DUS-based three-dimensional (2D/3D) techniques that generate pseudo-3D volumes from summed 2D plaque areas; however, its accuracy has not been reported. We aimed to determine 3DVUS accuracy for plaque volume measurement with special emphasis on small plaques (a hallmark of early atherosclerosis). The in vitro study consisted of nine phantoms of different volumes (small and medium-large) embedded at variable distances from the surface (superficial vs. >5 cm-depth) and comparison of 3DVUS data generated using a novel volumetric-linear array method with the real phantom volumes. The in vivo study was undertaken in a rabbit model of atherosclerosis in which 3DVUS and 2D/3D volume measurements were correlated against gold-standard histological measurements. In the in vitro setting, there was a strong correlation between 3DVUS measures and real phantom volume both for small (3.0-64.5 mm(3) size) and medium-large (91.1-965.5 mm(3) size) phantoms embedded superficially, with intraclass correlation coefficients (ICC) of 0.99 and 0.98, respectively; conversely, when phantoms were placed at >5 cm, the correlation was only moderate (ICC = 0.67). In the in vivo setting there was strong correlation between 3DVUS-measured plaque volumes and the histological gold-standard (ICC = 0.99 [4.02-92.5 mm(3) size]). Conversely, the correlation between 2D/3D values and the histological gold standard (sum of plaque areas) was weaker (ICC = 0.87 [49-520 mm(2) size]), with large dispersion of the differences between measurements in Bland-Altman plots (mean error, 79.2 mm(2)). 3DVUS using the volumetric-linear array method accurately measures plaque volumes, including those of small plaques. Measurements are more accurate for superficial arterial territories than for deep territories.S

Allies Already Poised to Comply: How Social Proximity Affects Lactation-at-Work Law Compliance

This study demonstrates how legal compliance may be better achieved when organizations include individuals who will advocate for newly codified rights and related accommodations. To understand compliance with a new law and the rights it confers, this article examines as its case study the Lactation at Work law, which amends the Fair Labor Standards Act to mandate basic provisions for employees to express breast milk at work. In particular, this study interviewed those organizational actors who translate the law into the policies affecting workers\u27 daily lives: supervising mangers and human resources personnel. Those studied in this article were “Allies Already:” friends or relatives of breastfeeding workers, or ones themselves, who held pro‐breastfeeding values and understood the complexities of combining lactation and employment. They mobilized within their organization to comply with the law swiftly and fully—often even overcomplying. This article demonstrates how heightened compliance, particularly with new laws, may be achieved even without directly affected actors mobilizing their own rights if allies champion needed accommodations

Longitudinal blood biomarker trajectories in preclinical Alzheimer's disease

INTRODUCTION: Plasma biomarkers are altered years prior to Alzheimer's disease (AD) clinical onset. METHODS: We measured longitudinal changes in plasma amyloid-beta (Aβ)42/40 ratio, pTau181, pTau231, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) in a cohort of older adults at risk of AD (n = 373 total, n = 229 with Aβ and tau positron emission tomography [PET] scans) considering genetic and demographic factors as possible modifiers of these markers' progression. RESULTS: Aβ42/40 ratio concentrations decreased, while NfL and GFAP values increased over the 4-year follow-up. Apolipoprotein E (APOE) ε4 carriers showed faster increase in plasma pTau181 than non-carriers. Older individuals showed a faster increase in plasma NfL, and females showed a faster increase in plasma GFAP values. In the PET subsample, individuals both Aβ-PET and tau-PET positive showed faster plasma pTau181 and GFAP increase compared to PET-negative individuals. DISCUSSION: Plasma markers can track biological change over time, with plasma pTau181 and GFAP markers showing longitudinal change in individuals with preclinical AD. HIGHLIGHTS: Longitudinal increase of plasma pTau181 and glial fibrillary acidic protein (GFAP) can be measured in the preclinical phase of AD. Apolipoprotein E ε4 carriers experience faster increase in plasma pTau181 over time than non-carriers. Female sex showed accelerated increase in plasma GFAP over time compared to males. Aβ42/40 and pTau231 values are already abnormal at baseline in individuals with both amyloid and tau PET burden