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This paper addresses the critical issue of leading edge erosion (LEE) on modern wind turbine blades (WTBs) caused by solid particle impacts. LEE can harm the structural integrity and aerodynamic performance of WTBs, leading to reduced efficiency and increased maintenance costs. This study employs a novel particle-based approach called hybrid peridynamics–discrete element method (PD–DEM) to model the impact of solid particles on WTB leading edges and target material failure accurately. It effectively captures the through-thickness force absorption and the propagation of stresses within the leading edge coating system composed of composite laminates. The amount of mass removed and the mean displacement of the target material points can be reliably calculated using the current method. Through a series of tests, the research demonstrates the method’s ability to predict impact force changes with varying particle size, velocity, impact angles and positions. Moreover, this study offers a significant improvement in erosion prediction capability and the development of design specifications. This work contributes to the advancement of WTB design and maintenance practices to mitigate LEE effectively.

Although cell-free DNA (cfDNA) prenatal screening is widely used and has high sensitivity and specificity, there are circumstances in which the screening does not provide an interpretable result. Although this is relatively uncommon, it happens enough that clinical implications and potential reasons for follow-up should be studied and assessed. This study was designed to evaluate outcomes for pregnancies with nonreportable results on cfDNA screening tests.This study was a secondary analysis of the data from a multicenter prospective observational study of cfDNA screening for aneuploidy and 22q11.2 deletion syndrome. All patients were tested for trisomies 13, 18, and 21, as well as the 22q11.2 deletion syndrome, and all patients had confirmatory testing on the newborns in addition to collecting obstetric and perinatal outcomes. Inclusion criteria were women older than 18 years and at greater than 9 weeks of gestation with a singleton pregnancy. Exclusion criteria were having received cfDNA screening results before enrollment, organ transplant, ovum donation, vanishing twin, or being unwilling to provide a newborn sample. The primary outcome was the rate of adverse obstetrical and perinatal outcomes, including aneuploidy; preterm birth at less than 28, 34, or 37 weeks' gestation; preeclampsia; small for gestational age birth; and a composite outcome that included preterm birth before 37 weeks, preeclampsia, stillbirth at greater than 20 weeks, and small for gestational age.Final analyses included 17,851 individuals who had cfDNA screening, confirmatory genetic testing on the newborn, and obstetrical and perinatal outcomes recorded. Nonreportable results were found in 602 individuals (3.4%) after the first draw, with 32.2% of these due to low fetal fraction. Another third of the cohort had patterns where the risk of aneuploidy was uninterpretable but with an adequate fetal fraction, and in the final third, the fetal fraction could not be measured. Of the original 602 cases of nonreportable findings, 427 had a second draw, with 112 of these (26.2%) again having nonreportable results. There were no significant differences in baseline characteristics of age and parity for those with successful versus nonreportable test results; gestational age was significantly higher in individuals with nonreportable results (14.4 vs 13.4 weeks, P< 0.001), as was body mass index (26.2 vs 31.3), and the rate of chronic hypertension (4.0% vs 9.7%).In this cohort, there were 133 genetically confirmed trisomies, with 100 fetuses with trisomy 21, 18 individuals with trisomy 18, and 15 individuals with trisomy 13. Overall, the rate of aneuploidy was 1.7% in individuals with nonreportable results, versus 0.7% in those with reported results (P= 0.013; adjusted odds ratio [aOR] 2.1; 95% confidence interval [CI], 1.1–4.0). Rates of preterm birth were also higher in those with nonreportable test results, with delivery at less than 34 weeks at 1.5% in those with a test result, 4.6% in those with one nonreportable test result and 6.9% in those with a second nonreportable test result (aOR, 2.2 and 2.7; 95% CI, 1.4–3.4 and 1.2–6.0, respectively). Preeclampsia showed a similar trend, with rates climbing from 3.9% in those with a reported result to 9.4% with 1 nonreportable result and 16.8% with 2 (aOR, 1.4 and 2.0; 95% CI, 1.0–1.9 and 1.1–3.7, respectively). Chances of live birth were significantly reduced in pregnancies with a nonreportable results (aOR, 0.20; 95% CI, 0.13–0.30), with the chances decreasing more after a second nonreportable test result (aOR, 0.11; 95% CI, 0.06–0.23).The study found that nonreportable cfDNA screening results are associated with an increased risk for aneuploidy, preterm birth, and preeclampsia, with a gradient of increased risk with a second failed test. This adds to literature with conflicting findings surrounding obstetrical complications in those with altered cfDNA levels and with most studies largely focused on characteristics that may be predictive of a nonreportable result rather than outcomes associated with nonreportable results. These results can inform clinicians who have patients with nonreportable test results in a way that may help them provide better care; future research should focus on more fully understanding the adverse outcomes associated with nonreportable tests to maximize this ability for clinicians in the future. Further research should also focus on specific populations or diagnoses to understand if there are fundamental differences in different groups of individuals.

Peridynamics (PD) theory is a promising technique for modeling solids with discontinuities. Short-range repulsive force models are commonly employed in PD impact event simulations. Despite their extensive usage, short-range force models do not take damping, friction, and tangential force components into account and hence are unable to effectively describe energy dissipation, leading to uncertainty in the calculation of contact forces. However, the accuracy of impact simulations using alternate contact models has not been extensively investigated in the context of PD impact simulations. The Discrete Element Method (DEM) has been proven to be the most reliable and effective approach to model collision processes between distinct solid objects. This work presents, a particle-based hybrid PD-DEM model to accurately predict the particle impact forces and the resulting damage to the target material. The present model brings together the unique capabilities of PD and DEM and has the potential to make use of the various DEM contact laws, which allow the development and adjustment of relevant contact forces in the normal and tangential directions. Furthermore, damping effects, friction, and intra-particle stiffness are incorporated into the simulations through DEM. The proposed method has been used for modeling material failure after being validated and verified for the contact parameters during the impact process. The predicted damage patterns and resulting material loss demonstrate good agreement with the experimental results reported in the literature.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ajog.2010.06.030 Byline: Padmashree Chaudhury (a), Sina Haeri (a), Amanda L. Horton (b), Honor M. Wolfe (a), William H. Goodnight (a) Keywords: birthweight; fetal growth restriction; gastroschisis; ultrasound Abstract: Most ultrasound estimated fetal weight (EFW) formulas incorporate abdominal circumference, which may overstimate growth restriction in fetal gastroschisis. The aim of this study was to determine the optimal ultrasound formula for prediction of birthweight and fetal growth restriction (FGR) in gastroschisis. Author Affiliation: (a) University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC (b) North Shore University Health System, Evanston, IL Article History: Received 27 February 2010; Revised 6 May 2010; Accepted 14 June 2010 Article Note: (footnote) Authorship and contribution to the article is limited to the 5 authors indicated. There was no outside funding or technical assistance with the production of this article., Cite this article as: Chaudhury P, Haeri S, Horton AL, et al. Ultrasound prediction of birthweight and growth restriction in fetal gastroschisis. Am J Obstet Gynecol 2010;203:395.e1-5.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ajog.2010.04.048 Byline: Arthur M. Baker (a), Sina Haeri (a), Richard L. Klein (b), Kim Boggess (a) Keywords: oxidative stress; paraoxonase 1; preterm birth Abstract: The objective of the study was to determine whether an association exists between low paraoxonase 1 activity and dyslipidemia at midgestation and preterm birth. Author Affiliation: (a) Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, NC (b) Division of Endocrinology, Metabolism, and Medical Genetics, Department of Medicine, Medical University of South Carolina, and Research Service, Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, SC Article History: Received 8 February 2010; Revised 13 April 2010; Accepted 29 April 2010 Article Note: (footnote) This study was supported in part by grants from the University of North Carolina Medical Alumni Endowment Fund (to A.M.B.), the North Carolina Translational and Clinical Sciences Institute (to A.M.B.), and a Department of Veterans Affairs MERIT award (to R.L.K.)., Cite this article as: Baker AM, Haeri S, Klein RL, et al. Association of midgestation paraoxonase 1 activity and pregnancies complicated by preterm birth. Am J Obstet Gynecol 2010;203:246.e1-4.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ajog.2009.06.017 Byline: Sina Haeri (a), Marla Shauer (b), Monica Dale (b), Jennie Leslie (b), Arthur M. Baker (a), Stephanie Saddlemire (b), Kim Boggess (a) Keywords: highly active antiretroviral therapy; human immunodeficiency virus; low birthweight; pregnancy; preterm birth Abstract: Our aim was to examine perinatal outcomes in women who are infected with human immunodeficiency virus (HIV) and who receive highly active antiretroviral therapy compared with the general population. Author Affiliation: (a) Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC (b) Department of Obstetrics and Gynecology, Washington Hospital Center, Washington, DC Article History: Received 5 February 2009; Revised 28 April 2009; Accepted 5 June 2009 Article Note: (footnote) Supported by the MedStar Research Institute and a Washington Hospital Center Graduate Medical Education Research Grant., Cite this article as: Haeri S, Shauer M, Dale M, et al. Obstetric and newborn infant outcomes in human immunodeficiency virus-infected women who receive highly active antiretroviral therapy. Am J Obstet Gynecol 2009;201:315.e1-5.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ajog.2009.05.037 Byline: Arthur M. Baker (a), Richard L. Klein (b), Kevin L. Moss (c), Sina Haeri (a), Kim Boggess (a) Keywords: preeclampsia; pregnancy; serum lipids Abstract: We sought to determine whether serum lipids at midgestation differ between normotensive women and women developing mild and severe preeclampsia. Author Affiliation: (a) Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC (b) Division of Endocrinology, Metabolism, and Medical Genetics, Department of Medicine, Medical University of South Carolina, and Research Service, Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, SC (c) School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC Article History: Received 5 February 2009; Revised 21 April 2009; Accepted 20 May 2009 Article Note: (footnote) Cite this article as: Baker AM, Klein RL, Moss KL, et al. Maternal serum dyslipidemia occurs early in pregnancy in women with mild but not severe preeclampsia. Am J Obstet Gynecol 2009;201:293.e1-4. , This study was supported by a Grant from the University of North Carolina Medical Alumni Endowment Fund (A.M.B.) and funding from a Department of Veterans Affairs MERIT award (R.L.K.).

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ajog.2008.06.066 Byline: Sina Haeri (a), Jane Khoury (b), Oormila Kovilam (c), Menachem Miodovnik (a) Keywords: diabetes; fetal growth restriction; pregnancy; vasculopathy Abstract: The purpose of this study was to test whether vasculopathy in type 1 diabetes mellitus (DM) is associated with fetal growth abnormalities. Author Affiliation: (a) Department of Obstetrics and Gynecology, Washington Hospital Center, Washington, DC (b) Center for Epidemiology and Biostatistics, Cincinnati Children's Hospital Medical Center, University of Cincinnati School of Medicine, Cincinnati, OH (c) Department of Obstetrics and Gynecology, University of Cincinnati School of Medicine, Cincinnati, OH Article History: Received 1 March 2008; Revised 2 May 2008; Accepted 21 June 2008 Article Note: (footnote) Cite this article as: Haeri S, Khoury J, Kovilam O, et al. The association of intrauterine growth abnormalities in women with type 1 diabetes mellitus complicated by vasculopathy. Am J Obstet Gynecol 2008;199:278.e1-278.e5.

The effects of interstitial gas on the spreadability of Inconel 718 powder under conditions relevant to powder-bed fusion additive manufacturing (PBF-AM) are investigated through high-fidelity discrete element method-lattice-Boltzmann (DEM-LB) simulations. Here, a fine computational grid fully resolves the flow of inert gases around each grain. Furthermore, Inconel 718 powder is fully characterised, and the DEM contact models are calibrated via a rigorous procedure devised specifically for metallic powders in additive manufacturing. This procedure involves angle of repose and slide tests, nano-CT imaging, and shear cell experiments. The spreading behavior of Inconel 718 by a blade is then simulated in both vacuum and gaseous environments. The findings reveal that the presence of inert gases increase the amount of deposited powder and the bed thickness. As the blade speed increases, the disparity in powder deposition between gaseous and vacuum surroundings becomes more pronounced. Moreover, it is observed that the newly deposited particles are disrupted by the wake of the blade, given that the gas velocity near the bed can exceed the terminal velocities of most particle size classes in the simulation.

The aim of this study was to assess the performance of cell-free DNA (cfDNA) screening to detect sex chromosome aneuploidies (SCAs) in an unselected obstetrical population with genetic confirmation.

In this article, incompressible, continuum regime, viscous flow of Newtonian fluid in two-dimensional (2D) wall-driven enclosures consisting of regular, square shaped, corrugations on the bottom wall is studied numerically. Steady and consistent simulation results are obtained using kinetic theory based lattice Boltzmann equation method (LBM) and solution of Navier–Stokes equation based on fictitious domain method (FDM). First, numerical validation is performed by comparing LBM and FDM results for velocity profiles at particular sections inside the enclosures and vertical velocity gradient at the top of the corrugation cavity. Flow features are then compared for variations in Reynolds number, bottom-wall corrugation height and number of these corrugations. Further, complex eddy dynamics with respect to input parameters and geometry is discussed in detail. Flow transition Reynolds numbers showing distinct flow behavior are found. The numerical results obtained are verified and appear to be consistent with the previously published results for 2D flow inside slender and shallow cavity enclosures. [ABSTRACT FROM AUTHOR]

This paper presents efforts to improve the boundary efficiency and accuracy of a compact finite difference scheme, based on its composite template. Unlike precursory attempts the current methodology is unique in its quantification of dispersion and dissipation errors, which are only evaluated after the matrix system of equations has been rearranged for the derivative. This results in a more accurate prediction of the boundary performance, since the analysis is directly based on how the derivative is represented in simulations. A genetic algorithm acts as a comprehensive method for the optimisation of the boundary coefficients, incorporating an eigenvalue constraint for the linear stability of the matrix system of equations. The performance of the optimised composite template is tested on one-dimensional linear wave convection and two-dimensional inviscid vortex convection problems, with uniform and curvilinear grids. In all cases, it yields substantial accuracy and efficiency improvements while maintaining stable solutions and fourth-order accuracy. [ABSTRACT FROM AUTHOR]

This study aimed to assess the feasibility of single-access fetal endoscopy (SAFE) for the management of myelomeningocele (MMC) using intrauterine carbon dioxide as a distension medium in a sheep model.This prospective experimental case-control study investigated 12 lamb fetuses that had a myelomeningocele-like defect surgically created on the 75th day of gestation. Four fetuses remained untreated (control group), and eight fetuses had MMC repair using two fetoscopic approaches with carbon dioxide used to distend the amniotic cavity. A collagen patch was placed over the defect and secured with surgical sealant. Four animals had a two-port fetoscopic procedure, and four animals had SAFE. Clinical and pathologic studies were performed after delivery.This study confirmed the validity of the animal MMC model. None of the control animals was able to stand or walk, and all had a significant defect in the lumbar area with continuous leakage of cerebrospinal fluid, ventriculomegaly, and a Chiari-II malformation. All the treated animals, independently of the number of ports used in the repair, were able to walk and had a closed defect with resolution of the Chiari malformation.The SAFE patch and glue coverage of surgically created fetal MMC is feasible and effective in restoring gross neurologic function in the fetal lamb model.

Twin‐twin transfusion syndrome complicates up to 15% of monochorionic diamniotic gestations. Current recommendations for sonographic surveillance in monochorionic diamniotic pregnancies for detection of twin‐twin transfusion syndrome vary. Our objective was to determine an appropriate frequency of sonographic surveillance to optimize detection of twin‐twin transfusion syndrome in monochorionic diamniotic gestations. A retrospective cohort analysis of all nonanomalous monochorionic diamniotic twins delivered at the University of North Carolina over a 9‐year period was performed. The rate and gestational age of twin‐twin transfusion syndrome onset were calculated. The time to the diagnosis of twin‐twin transfusion syndrome was evaluated by a Kaplan‐Meier survival curve; clinical factors at initial sonography were examined for their use in prediction of twin‐twin transfusion syndrome. Of the 577 twin deliveries, 145 (25%) were monochorionic diamniotic and included for analysis. The rate of twin‐twin transfusion syndrome was 17.93% (n = 26). The mean frequency of surveillance ± SD before diagnosis of twin‐twin transfusion syndrome was 3.1 ± 2.1 weeks. The mean gestational age at diagnosis of twin‐twin transfusion syndrome was 21.3 ± 3.4 weeks (range, 15–29 weeks). Both a discordant maximum vertical amniotic fluid pocket (>65% difference) and a discordant estimated fetal weight (>25% difference) at initial sonography showed a significantly shorter time to diagnosis of twin‐twin transfusion syndrome (P< .0001). Evaluation for twin‐twin transfusion syndrome should begin in the second trimester. Weekly surveillance for those pregnancies with estimated fetal weight or maximum vertical pocket discordance is recommended. For those with a concordant estimated fetal weight and maximum vertical pocket, sonographic evaluation every 2 weeks is warranted to 28 to 30 weeks. After that, development of twin‐twin transfusion syndrome is less likely, and a different paradigm of antenatal testing may be reasonable.

The article presents a case study of an unborn baby with enlarged bladder, which resulted in kidney failure, lungs get were squished, and after the delivery the baby was put on dialysis till he met the criteria for a kidney transplant.

Vitamin D and its active metabolite, 1,25-dihydroxyvitamin D (25(OH)D), may play an important role in the pathogenesis of preeclampsia. A number of investigators have reported lower maternal vitamin D concentrations in women after diagnosis of preeclampsia. Moreover, there is evidence that supplementation with vitamin D may reduce the risk of preeclampsia. Previous studies showing an association between vitamin D deficiency early in pregnancy and preeclampsia did not focus on women with severe disease.

Force transmission in granular media occurs through an inhomogeneous network of inter-particle contacts referred to as force-chains. A thorough understanding of the structure of these chains is indispensable for a better comprehension of the macroscopic signatures they generate. This paper introduces Force-Chain Finder (FCF), an open-source software tool designed for detecting force-chains in granular materials. Leveraging the stress tensor computed for each particle based on its interactions with neighbouring particles, the tool effectively identifies the magnitude and direction of the most compressive principal stress. Through a recursive traversal of particles and their neighbours, force-chains are robustly detected based on the alignment of the principal stress directions, which is decided by a parameter α (an angle in radians). The software provides a comprehensive suite of post-processing features, including the exportation of results in different formats, enabling detailed analysis of specific regions and dynamic phenomena. Additionally, the software facilitates the computation of statistical measures pertaining to chain size and population. By streamlining the identification and characterization of force-chains within discrete element method (DEM) simulations, this tool significantly enhances the efficiency and accuracy of force-chain analysis. Thus, the software promotes deeper insights into the behaviour of granular materials by enabling researchers to effortlessly detect and analyse force-chains. Program Title: Force Chain Finder (FCF) CPC Library link to program files: https://doi.org/10.17632/33pkc4f63t.1 Developer's repository link: https://github.com/Particles-Research/Force%5fChain%5fFinder%5fPublic/tree/main Licensing provisions: GNU General Public License 3 Programming Language: C++, Python Supplementary material: Illustrative examples Nature of the Problem: FCF has been developed with the primary objective of efficiently and comprehensively detecting force networks that arise in Discrete Element Modelling (DEM) simulations of granular flow. Solution Method: The method is based on the work of "J. Peters, M. Muthuswamy, J. Wibowo, and A. Tordesillas, Characterization of force chains in granular material, Physical Review E 72, 041307 (2005)". It utilizes the concept of minor principal stress to identify quasilinear chains, each consisting of at least three particles. However, significant algorithmic modifications have been implemented to enhance the accuracy of the procedure, enabling the detection of chain branching and merging. [ABSTRACT FROM AUTHOR]

A new relaxed multi-direct-forcing immersed boundary-cascaded lattice Boltzmann method (MDF IB-CLBM) is proposed in this paper. This new technique improves the efficiency and accuracy of implementing no-slip boundaries on a single graphics processing unit (GPU). The traditional MDF-IBM method essentially solves a linear system iteratively with a relaxation parameter 1.0. By introducing an estimated optimal relaxation parameter, no-slip boundary is fulfilled after only one iteration in a typical case of flow around a fixed cylinder. This is a 7-fold speed-up over the traditional method. Since it is computationally expensive to calculate the estimated optimal relaxation parameter for moving boundaries in every time step, the impact of many factors on the value of the estimated optimal relaxation parameter is investigated. The studied parameters include the discrete delta function, shape of no-slip boundary, the relative distance between several no-slip boundaries, the spacing size between the Lagrangian points, and the relative movement of boundaries over underlying lattices. It is found that the first three factors have a more pronounced influence. Therefore, by considering these three key factors, an appropriate constant relaxation parameter can be determined before starting the simulations. Moreover, the relaxed method provides significant improvement to the traditional MDF-IBM with only a few modifications. The effectiveness of the method is demonstrated by dealing with the flow around a fixed cylinder, the flow past several obstacles, a particle moving in a linear shear flow, and the sedimentation of multiple particles in an enclosure. [ABSTRACT FROM AUTHOR]