INVESTIGATION OF NUMERICAL SCHEMES IN AIR CAVITY COMPUTATIONS

Air cavity and air chamber concepts have been proven to be an efficient way for drag reduction in low-speed ships. Series of experiments were conducted in the SSPA cavitation tunnel to simulate the working conditions of an air filled cavity under the hull of a ship. In this paper, study is extended with a numerical validation using a CFD Open Source solver, OpenFOAM (OF). Volume of fluid (VOF) approach, which uses phase volume fraction (alpha) is used to compute the incompressible two-phase viscous flow. The influence of different numerical methodologies on the advection of "alpha" is studied. Different schemes from diffusive first-order to higher order TVD (Total Variation Dimensioning) schemes like SUPERBEE are tested. Results are also drawn from counter-gradient convective flux implementation in OF VOF approach. Conclusions are drawn from the wave profile, wave sloshing pressure force and viscous force. It was observed that, as more compressive interface capturing methods were used, the aft force was better predicted but distorts the wave profile and under predicts the beach plate force

Randomized controlled trial of antenatal magnesium sulfate for short-term neuroprotection in premature neonates

Objective: To test the hypothesis that antenatal magnesium sulfate (MgSO4) has a short term neuroprotective role in the early neonatal period, when given to women considered at risk for preterm delivery in a developing country. Study Design: Randomized, placebo-controlled, open label, trial. Participants: A total of 126 mothers who delivered at or below 34 weeks gestation were randomized to receive either antenatal MgSO4 (cases) or normal saline as placebo (controls). A total of 108 babies born were observed for the primary and secondary outcomes. Primary Outcome: The composite of the incidence of death and intraventricular hemorrhage (IVH) by cranial ultrasonography in surviving preterm infants. Results: There were 6 deaths in cases and 11 deaths in controls (relative risk [RR]: 0.54; 95% confidence interval [CI]: 0.2173-1.369; p=0.18). A statistically significant reduction in the number of IVH was observed in cases (n=1) compared to controls (n=9) (RR: 0.11; 95% CI: 0.0145-0.897; p=0.016) with a number needed to treat of 7. Conclusion: Antenatal MgSO4 resulted in a significant reduction in the risk of IVH in preterm infants born at or below 34 weeks of gestation

In silico screening of phytoconstituents of Cissus quadrangularis and Chromolaena odorata against proteins of antimicrobial resistance and wound healing

In silico screening is a methodological approach, which is invaluable for rational drug design and the identification of potential therapeutic agents. In the context of antibiotic-resistant infectious wounds, molecular docking can provide a deeper understanding of how phytocompounds might interfere with bacterial virulence and antibiotic resistance. In this study, proteins involved in antimicrobial resistance and wound healing were docked against major phytoconstituents of ethyl acetate extract of Cissus quadrangularis (EACQ) and ethanol extract of Chromolaena odorata (EECO), two medicinal plants that have been traditionally used. Receptor structures for interleukin 6 (PDB id: 1n26) IL6, of human and mice, IL6 (Uniprot id p 20607) of rat, vascular endothelial growth factor (VEGFR, PDB id: 2ctw) for human, mice, rat and penicillin binding protein 2a (PBP2a, PDB id: 1vqq) of S. aureus were downloaded from the database of the RCSB protein data bank. The ligand structures were downloaded from PubChem compound database in structure data file (.SDF) format. The docking studies were conducted using Autodock4. and the results of the docking analysis were visualised using Discovery Studio Visualizer. The docking log (dlg) file, featuring an RMSD table, provides binding energy values in Kcal/mol for each molecule at its optimal docked postures, offering insights into structural accuracy and ligand-receptor interaction strength in molecular docking simulations. In silico analysis of ligands showed that squalene of EACQ and epilupeol of EECO had the least binding energy towards proteins of antimicrobial resistance and wound healing. Thus, these compounds could emerge as promising lead molecules against infectious wounds

Satellite chlorophyll concentration as an aid to understanding the dynamics of Indian oil sardine in the southeastern Arabian Sea

Coastal waters of Kerala, which form an integral part of the Malabar upwelling zone off the southwest coast of India, constitute an important fishing region for small pelagics. Satellite remote sensing data from 1998−2014 were used to test the hypothesis that fluctuations in the landings of Sardinella longiceps, the major pelagic fish landed in the area designated as the South Eastern Arabian Sea (SEAS), are influenced by seasonal variability in phytoplankton biomass (measured as chlorophyll a [chl a] concentration), under the changing strength of physical para - meters such as sea surface temperature (SST), alongshore wind stress, Ekman mass transport, sea level anomaly (SLA) and Kerala rainfall. Multiple linear regression analysis (MLRA) was used to assess the influence of physical forcing mechanisms on chl a concentration on monthly and seasonal scales. We found that SLA, alongshore wind stress, SST and rainfall were ranked 1 to 4, respectively, and the first 3 factors significantly influenced the chl a concentration of SEAS. Pearson’s correlation analysis between monthly chl a and sardine landing (with chl a leading) showed a maximum positive correlation (+0.26) at 2 and 3 mo lags, emphasizing that the influence of chl a on the fishery of S. longiceps is seasonal (r = 0.35 for seasonal lead−lag correlation) in the coastal waters of SEAS. Variation in phytoplankton biomass, as evidenced by chl a fluctuations, seems to have a decisive role in regulating the physiological condition of larvae spawned during the southwest monsoon season, their juveniles and finally the adults that are recruited into the fishery in the next season. Using the quantity of phytoplankton as a predictive tool will exploit the presumptive trophic link to aid understanding of sardine fishery dynamics in upwelling zones

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Predicting risk for Alcohol Use Disorder using longitudinal data with multimodal biomarkers and family history: a machine learning study.

Predictive models have succeeded in distinguishing between individuals with Alcohol use Disorder (AUD) and controls. However, predictive models identifying who is prone to develop AUD and the biomarkers indicating a predisposition to AUD are still unclear. Our sample (n = 656) included offspring and non-offspring of European American (EA) and African American (AA) ancestry from the Collaborative Study of the Genetics of Alcoholism (COGA) who were recruited as early as age 12 and were unaffected at first assessment and reassessed years later as AUD (DSM-5) (n = 328) or unaffected (n = 328). Machine learning analysis was performed for 220 EEG measures, 149 alcohol-related single nucleotide polymorphisms (SNPs) from a recent large Genome-wide Association Study (GWAS) of alcohol use/misuse and two family history (mother DSM-5 AUD and father DSM-5 AUD) features using supervised, Linear Support Vector Machine (SVM) classifier to test which features assessed before developing AUD predict those who go on to develop AUD. Age, gender, and ancestry stratified analyses were performed. Results indicate significant and higher accuracy rates for the AA compared with the EA prediction models and a higher model accuracy trend among females compared with males for both ancestries. Combined EEG and SNP features model outperformed models based on only EEG features or only SNP features for both EA and AA samples. This multidimensional superiority was confirmed in a follow-up analysis in the AA age groups (12-15, 16-19, 20-30) and EA age group (16-19). In both ancestry samples, the youngest age group achieved higher accuracy score than the two other older age groups. Maternal AUD increased the model's accuracy in both ancestries' samples. Several discriminative EEG measures and SNPs features were identified, including lower posterior gamma, higher slow wave connectivity (delta, theta, alpha), higher frontal gamma ratio, higher beta correlation in the parietal area, and 5 SNPs: rs4780836, rs2605140, rs11690265, rs692854, and rs13380649. Results highlight the significance of sampling uniformity followed by stratified (e.g., ancestry, gender, developmental period) analysis, and wider selection of features, to generate better prediction scores allowing a more accurate estimation of AUD development

Flow Analysis in wavy pipes using Large Eddy Simulation

Several types of heat exchangers are used in various industries depending on their applications and limitations. One of the most common arrangements for flow paths within a heat exchanger are counter- flow and parallel flow, which are manufactured at Tetra Pak Food Processing Unit, Lund. These long narrow pipes are given corrugation at the wall for enhanced efficiency. It was important to study and understand the flow and thermal distribution inside these pipes. In the current work, computation fluid dynamics (CFD) is used to understand and quantify these characteristics. Current work is based a Large Eddy Simulation of the flow where it is possible to resolve most of the eddies and less is modeled. In the current work, an in-house Chalmers solver, CALC-BFC is used for analysis. In the early stages of the thesis, it was important to validate the CALC solver and numerical methodologies. Thus the code is compared with the commercial software ANSYS Fluent and Star-CCM+. Later on, several refined meshes are simulated to realize how much is resolved and whether that is sufficient enough. Later on, study is done on the different implementations for the current problem and its repercussions is analysed. Once the code is validated enough, an attempt is given to understand the flow phenomenon and heat enhancement due to the corrugation given on the pipe. Finally, the height of the corrugation is varied, keeping the outer radius constant and results are presented

INVESTIGATION OF NUMERICAL SCHEMES IN AIR CAVITY COMPUTATIONS

Air cavity and air chamber concepts have been proven to be an efficient way for drag reduction in low-speed ships. Series of experiments were conducted in the SSPA cavitation tunnel to simulate the working conditions of an air filled cavity under the hull of a ship. In this paper, study is extended with a numerical validation using a CFD Open Source solver, OpenFOAM (OF). Volume of fluid (VOF) approach, which uses phase volume fraction (alpha) is used to compute the incompressible two-phase viscous flow. The influence of different numerical methodologies on the advection of "alpha" is studied. Different schemes from diffusive first-order to higher order TVD (Total Variation Dimensioning) schemes like SUPERBEE are tested. Results are also drawn from counter-gradient convective flux implementation in OF VOF approach. Conclusions are drawn from the wave profile, wave sloshing pressure force and viscous force. It was observed that, as more compressive interface capturing methods were used, the aft force was better predicted but distorts the wave profile and under predicts the beach plate force